इंटरनेट
मानक
Disclosure to Promote the Right To Information
Whereas the Parliament of India has set out to provide a practical regime of right to
information for citizens to secure access to information under the control of public authorities,
in order to promote transparency and accountability in the working of every public authority,
and whereas the attached publication of the Bureau of Indian Standards is of particular interest
to the public, particularly disadvantaged communities and those engaged in the pursuit of
education and knowledge, the attached public safety standard is made available to promote the
timely dissemination of this information in an accurate manner to the public.
“जान1 का अ+धकार, जी1 का अ+धकार”
“प0रा1 को छोड न' 5 तरफ”
“The Right to Information, The Right to Live”
“Step Out From the Old to the New”
Mazdoor Kisan Shakti Sangathan
Jawaharlal Nehru
IS 787 (1956): Guide for inter conversion of values from
one system of units to another [PGD 1: Basic Standards]
“!ान $ एक न' भारत का +नम-ण”
Satyanarayan Gangaram Pitroda
“Invent a New India Using Knowledge”
“!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता ह”
है”
ह
Bhartṛhari—Nītiśatakam
“Knowledge is such a treasure which cannot be stolen”
IS : 787-1958
(
Reaffirmed
1964) )
( Reaffirmed
2005
Indian Standard
GUIDE FOR INTER-CONVERSION OF
VALUES FROM ONE SYSTEM OF
UNITS TO ANOTHER
( Sixth
Reprint JANUARY
1990)
.
UDC
511’16
0 Copyrighhr1967
‘.
RUREAU
MANAK
INDIAN
OF
BHAVAN,
9
BAHADUR
NEW
Gr 7
DELHI
ST’ANDARDS
SHAH
ZAFAR
MARG
110002
January %1957
IS:787019S6
Indian
Standard
GUIDE FOR INTER-CONVERSION
OF
VALUES FROM ONE SYSTEM OF
UNITS TO ANOTHER
Engineering
Standards
Sectional
Committee,
/
EDC 1
Chairman
Council
of
Delhi
DE K. S. KBIBHNAN
Members
SHRI F. Asavoa~
Scientific
& Industrial
Research,
New
Directorate Feneral of Supplies & DisposaIs ( Mmistry of Worka, Housing & Supply )
Cmtfal Board of Irrigation & Power
Engineering Research Department,
Hyderabad
Diiectorate
General of Observatories
(Mitt&y
of
Communications
)
The Institution of Engineer3 ( Indi )
Indian Engineering Association,
Calcutta
Indian Institute of Science, Bangalore
Coun&cibf
Sciintific
& Industrial
Research, New
SHBI BALRBBWAR NATE
DIBE~TO~
DIBECTOB GENERAL
Saar S. B. JOSRI
SHEI R. N. KAPIJB
DB R. S. KBISHNAN
&BX S. R. MEERA
!~BBI S. N. MUSEBJ~
Government Test House, Calcutta
SHBI K.D. BEAITACEAEJWC(Ubn&)
De B. R. NIJHAWM
Council of Scientific & Industrial
Research,
New
Delhi
SRILI V. R. RAGHAVAH
Ccntrd Water
Power Commission
COL J. R. SAMSON
Technical De& f opment ?Zstablishmcnt
( Weapons),
Ministry of Dcfence
LT-COL R. JANABDHANAN ( Affmw )
SHBI H. P. SINHA
Roads Organiution,
Ministry of Transport
SEBI J. M. TBEEAN ( Alkmk )
Sr81 J. M. SINHA
Engineering Association of India, Calcutta
%tral
Standards Office ( Ministry of Railways J
Sztp~ K. C. Soou
MAJOR CESEBAL H. WILLIAM
Council
of Scientific k Industrial Research.
New
Delhi
DB IalL c. VEXUfAH ( &ob&% )
Director, IS1
Staff
SBBI T. P~~BHAH~AH
Tcchnicd Officer, IS1
BUREAU
MANAK
OF
BHAVAN,
INDIAN
STANDARDS
9 BAHADUR
SHAH
NEW DELHI 110002
ZAFAR
MARC
CONTENTS
PAOl
0.
FOREWORD . . .
...
.. .
...
.. .
3
1.
SCOPE
.. .
. ..
...
...
5
2.
TERMINOLOGY
...
.. .
...
6
2.1
Decimal
...
.
...
.. .
6
2.2
Significant
Figures
...
. .
...
6
2.3
Significant
Part
.. .
.
.. .
7
2.4
Order of Magnitude
..
..
...
7
2.5
Fineness of Rounding
.. .
...
...
8
...
Places
...
3.
CONVERSIONFACTORS .
..
. ..
...
9
4.
SIONIPICANCE
VALUES
...
. *.
...
10
Values
...
...
.. .
10
...
.. .
10
.. .
11
.. .
.. .
20
...
...
. ..
22
.. .
..
. ..
26
. .
...
. ..
.. .
26
,.
...
. ..
...
28
APPENDIX A - TABLE IV DERIVED CONVERWONFACTORS AND
COMMONLYUSED UNITS . . .
...
...
...
30
APPENDIX B - BRIEF SUMMARY OF INSTRUCTIONSFOR REWRITINO VALUES BEFORECONVERSION . . .
.a,
...
32
5.
OF GIVEN
4.1
Exact Terminating
4.2
Inexact Values for Exact Quantities
4.3
Inexact Values Subject to Inherent
4.4
Dimensional
4.5
Monetary
Designation
Values
...
PROCEDUREFOR CONVERSION
5.1
Rules
.. .
5.2
Monetary
Values
Values
Uncertainty
hdian Standard
GUIDE FOR INTER-CONVERSION OF
VALUES FROM ONE SYSTEM OF
UNITS TO ANOTHER
0.
FOREWORD
0.1 This Indii Standard was adopted by the Indian Stat&u&
Institution
on 8 December 1956 on approval by the Engineering Division Council
of the draft final&d on 19 October 1956 by the Engineering Standards
Sectional committee.
0.2 Thf Report of the Indii
Standards Institution Special Committee on
Weights and Measurer, submitted in 1949 recommending to Government
of India the adoption of the Metric System, has now been fully considered
and examined by the Planning Conmuss~‘on, and on its recommendation the
Oavanmcnt
has generally accepted the Report.
The preparation of this
Indii
Standard Guide for IntcrXonversion
of Values from One System of
Units to Another has become particularly necessary to implement the decision
of the Govcfnment to adopt the metric sy@em as the only system of weights
and measures for the country ( within the period of 10 years ). The need for
such a standard has existed for a long time in India, as also in other countries,
wherever more than one system of units fbr measuring similar quantities has
been in use
Gonvetaion of values from one system to another raises issues
of interchangeability of parts, precision of statement, and other rigid criteria.
0.9 So far as is known, in no country has this task been tackled Corn standards
From the early beginnings of the Indian
point of view in a general manner.
Standards Institution during the course of drafting speciiications on the basis
of known technological data collected from diverse sources, and in line with
the standards from different countries using different systems of units, it had
become necessary to inter-convert values from one set of units to another.
Furthermore, in view of the expectation that the coLlntry would adopt the
metric system at one time or another, it was decided that in all Indii
Standards, numerical values should be specified either in metric units or,
failing that, in terms of the units most commonly used in the particular
industry concerned, but in the latter case it was required that metric equivalents of values be added within brackets. All these needs for inter-conversion ofvalues fed to the development ofcertain’ideas which were gradually
put into use in the day-today working of the IS1 Directorate.
In due
course, these ideas began to take concrete form. This standard, in fact, is
the outcome of these develepments, and it may rightly be claimed that the
3
~,
procedures advocated in it have been tried out in practice for several years
I’fithin the Institution.
.
DOCUMENT ISO/TC
12 ( SEC
RECOMMENDATIONNa. 97
UNXTSOF THE MKSA SYSSPACE ANDTIME,
&.4 One of the tirst published contributions of value bearing on this subjeet
qpxwcd in the Ovemcas Edition of ‘Machinery Lloyd of 23 April 1955.
‘NM article was by L. W. Nickels of the Metrology Division of the National
Pla@cal Laboratory of UK, and was entitled “The Inter-Convcmion of
Inch and Metric Sizm in Engin6cririg Drawings” ( see ubo 1S1 Bulletin,
November 1955 ). A $tudy of Nickels paper will indicate that the limited
problem of inter-corwcrsion of linear duncnsions with special attention to
interdmngeahllity of parts has been ably tackled and the proccdurc proposed
But having been designed to deal with the limited
ia uite siitisfactory.
!
it
f
,.
pro1 km of linear dirncnsions, it does not readily lend itself to .gencralization
for usc in dealing with inter-conversion
of quantities other than linear.
B.S.350:1944
B.S. 1957:1953
IFJCIXJSXON
OF EQUIVALIZNTMETRIC VALUES IN SCIENTXFXCPAPERS.
National Physical Laboratory, Teddington, UK. 1948.
30.
.
ADAMS,G. C. PiUNCIPLESAND PRACTICE GOVERN]N~INTERCHANOEAEMIJTYANDSPECXFJCATXON
OF MANUFACTURING
LSMXTS
OF SIZSS,
Pnoc. ( A )
AS INFLUENCEDBY STATISTICALCONSXDBRATXONS.
Inst. Mcch. Eng., l“ol. 167, No. 2, pp. 154-169 ( 1953).
AST.M DMGNATXONE 29-50 RECOMMENDEDPRACTICE FOR DESIGNATING StGPJIFICANT
PLACESXNSPECIFIEDVALUES.
DOCUMENT
RULES FOR ROUNDN
1.1 This standard is intended to serve
values of physical quantities from one
another systcm of units; in particular,
draftsman in converting dimensions an{
from inches to millimetrcs.
,
ALSOIEC Doc 39 (UK)
1.1.1It also deals with tile conversi
administrators,
traders and industrialism
1.2 The significance ofspecificd
sion are also discussed.
values z
●Since revised.
ISO/TC 69 ( SECRETARIAT-6) 6 GENERAL DEFINITIONS
tSincc withdrawn.
$Sccond revision in
REI.ATtNOTD CHEMICALANDPHYSICALTEST RESULTS.
1972;
4
.-. ,, .,..
- .
-- . .
.
I
.
Guid
1. SCOPE
CONVERSION
FACTORSANDTABLES.-
I%CKOLS,L. W. /oc. cit. ( see 0.4),
0.8 In the usc of this Standard
Standards will be tcquired:
0.8 During the next 10 to 15 years, ~
change over from the existing sets of 1
metric units, it is hoped that this standa
the training and guidance of the person]
ed work of conversion, and will help th{
management
in respect ofdetailcd dime
quantities, reporting figurt?s, etc.
has been made to the following . ~
PRESENTATION
OF NIJMERICALVALUES.
THE MEASURESOF LENCTH ACT
THE INDIANCOINAOE( AMENDM
tIS: 3-194? INCH-MILLIMETREC(
$1S :696-1”955 CODE OF PRACq
DRAWINGS
FACT
*IS: 786-1956 CONVERSION
4MI In stating the procedure, a new concept designated as the signijicad @rt
da number has been introduced ( sce2+3 ). It must be understood, however,
that this term has been used only because no other better term was available.
The concept itself appears to be new, and the term maybe useful in teachiag
the w of logarithms to students; for in looking up the logarithm of a number
it is the ‘significant part of the number that is used to obtain the mantissa.
this standard, refercn~
THE STANDARDS
OFWEIONT Acq
*IS :2-1949
@JJ This Standard Guide, however, puts forth the Indian Standard
prordurc,
which is general enough for usc in the inter-conversion of all
quantities fmm any set M“units to any other.
It also discusses in some detail
the significance of stated values and shows how to assess their significance
fm the purpose of conversion. Jt incidentally lays down a standard practice
for stating and specifying values, so as to make their significance self-evident
beyond doubt and not subject to dilTcrent interpretations.
@.7 In preparing
DOCUMXHWISO/TC
12 ( SEC
QUAN~XTXE$
ANDUNITS,
,.
.
..
<.’
.
~
Docuumm
QUA-
Iw/TC
12 ( StCRlTARXAT-53 )
AND UNn’s.
l%R
T-m
or
DCCUMENT ISG/TG
12 (SRCRBTAUT-70)
197E DRAFT
Iso
RBCOYYBNDATION No. 97 FCDDAYENPAL Qumrrms
AND
UNITS OF TRB MKSA Stm~
AND QUANTITIBS AND U~rrs OF
SPACB AND TDD~.
THE STANDARDS OF Whom Acr, 1939. (ACT IX OF 1939 ).
THB MBASURESOF LBNCTEIAcr, 1889.
(ACT II OF 1939 ).
THE INDIAN COINAOK (AMENDMENT) ACT, 1955.
8J In the use of this Standard
Standards will he required:
Guide, ref~ence
to the following
Indian
*IS : 2-1949 RULES FOR ROUNDINOOFF NUMERICAL Vtium
71s : 3-1949INCH-MILLIYBTREGCNVBR~IONFOR INDUSTIUALUse
ENG~NESRIN~
OF PRACTICB FOR Crmq
;IS : 696-1955 CODB
DRAWINGS
*IS : 786-1956 CONVBRSION
FACTORSAND C~NWWUION
TABLES.
0.9 During the next 10 to 15 years, when the country will he effecting the
chinge over from the existing sets of units of weights and measures to the
metric units, it is hoped that this standard will provide the necessary hasis for
the training and guidance of the personnel directly concerned with the detailed work of conversion, and will help the engineer, designer, technologist and
management in respect of detailed dimensions on drawings, and in specifying
quantities, reporting figures, etc.
1. SCOPE
1.1 This standard is intended- to serve as a guide in converting numerical
values of physical quantities from one system of units of measurement to
another system of units; in particular, it should assist the designer and the
draftsman in converting dimensions and tolerances on engineering drawings
from inches to millimetres.
1.1.1 It also deals with the conversion
administrators, traders and industrialists.
of monetary
values of interest to
1.2 The significance-of specified values and how to interpret them for conversion are also discussed.
*Since revised.
f!Jinccwitil~wn.
~&amdmi#iooin
19M.
5
-
2.0 For the purpose of this standard the following detinitions &all apply.
2.1 Dednul~-AAueis~dtohaveasmanydocimalploca~
‘there are number of &urea in the value, starting from the decimal point and
ending with the last right-most figure in the value.
For examp!e:
Dthal Pkrcar
V&
O-029 50
5
4
6
21.029 5
2ocKPooooo1
291w
2
2
10.32 x IO
(scGNote2)
Nom1
-
In
writingdown valua it is recommended
for clarity
of expression that
a) the figure on either aide of the decimal are grouped in threes with clear w
in between as in the above examples, and
b) when the value is Las than udity, a zero precedea. the decimal
point.
NOTE2 - For the purpose of this standard, the expression 1@32X 10 shouJd be
taken to consist of two parts, the value proper which is 1092 and the unit ofexpcc&n
fa the value, W.
-A
value is said to have as many aignihnt
25
S~c8at
Pigum
figures as there are number of Sgures in the value, counting from the le&
moat non-zerofigure aad ending with the right-most figure in the value.
For example:
Sign$ant Figum
V&
O-02950
0.0295
lo%?9 5
2oOPooooo1
5 677.0
567 700
w77 x 10’
0 05&77
4
3
6
10
5
6
4
4
NOT= 1 - According to this definition all Xerox appearing at the end of an integer,
or of a decimal fraction, arc counted aa sigoificant.
This follows from the,daprcdinI~S~forrpe~~gvrlua(ru~4).
Inotberlbacb,cuet
6
rsral749sy
takenthatan
impk
that
comparison
ployed must
in the value,
rpedad~uein~I~~dterminatinginoneormorrKtor
of the value and in irr
3: c last zero haa a a’ ilkance in the determinatioh
analysis, tats, etc, cmwith other values.
% e methods of measurement,
have the requisite degree of ux~racy to impart significance to the lut figure
whether it is aero or not.
For eaamplcl
uare millia) If the minimum Wength of a material ia to be, say, 20 000 grams per
metre and the accuracy of measurement is of the order of 50 g/mm“L, then the
specified value may be written aa 2@0 kg/mm* or 20.0% 10’ g/mm* and not u
20 000 g/mm*; in other wordn, the i~umber of significant figures in the result of a
test rhould be only three, because the method of determination ia such that fourth
figure cannot in practice have any utility or rignikance.
b) A dimension may be specikd u 1 530 tlun, or 1590 cm, or l-530 metres or e.ven
1*530X lot mm, if the accuracy of measure ment is intended to bc of the order of
@5 or 1 mm.
On the other hand, if such a dimension is specilkd as 153 cm or
1.53 metre, it will imply an accuracy of a lower order of magnitude,
namely,
Smmorl
cm.
NOTB 2 - Thus the number of rignificant figures in a value in the absence of other
supplementary information, such as the tolerance or error, is taken to be an indication of
the accuracy of the physical quantity involved, that is at least so in Indian Standards
imued during the recent years.
In general engkeering
practice, however, due to the
absence of a mutually a reed convention, such a signilicancc is not always attached to
tt is highly desirable that t&~epractice followed in Indian
a stated value, altho 4.
Standards be adopted generally.
2.3 S&d&ant
Part of a number consists of the significant digits occurring
in the value written down as an integral number without a decimal point and
without the non-significant zeros.
For example:
SignijicantPart
5 690
569
100 295
5 677
value
0905 690
O-005 69
10.029 5
.
~~~7xxl~’
2000
2 x 10s
b76.00
2Oz
76;
2.4 order of Mapimde
- Two numbers are referred to in this standard
as having the same order of magnitude if the greater one is not more than
ten times the smaller.
For example:
a) The following
pai; ;f ;aIIea a;
.
2.15
1.69
1000
I 756 049
,,
,,
,,
,,
of the same order of magnitude
10
O-497 2
101-35
IS.2 x 10s
7
:
El~7w-l%6
b) But the following pairs are not of the same order of magnitude:
99
and
9-8
25
251
2,
1
16
162.9 x 10’
1: 15 ooo
c) Combining the concept of sign&ant part ( saa2.3 ) with that of
order of magnitude, it may be noted that the significant parts of
the pairs of values, given below, are of ,,the same order df
magnitude, though the values themselves may or may not be so:
Valw
23.4
and
O-0056
,,
10 x lo”
,,
Signijcant Parts
4-36
35.1
4-l
234 and 436
56
9, 351
10
41
2.5 Fineness of Rounding is the unit to which a iilue
is rounded OK
For example:
The value 125.1526 when rounded off by using various degrees
of finenessof rounding yi&s the rounded values as indicated below:
Finenessof Rounding
omo 5
Rout&d off Vah
125.152 5
125.153,
125-152
125155
125.15
125.2
125
l-3 x lo*
1 x 10L
O*OOl
o-002
O-005
0.01
6-l
1
10
100
NOTE 1 - While rounding off valuer *IS : 2-1949 shall be followed in all cases, with
the additional rule,that when fineness of rounding is not unity in the last place retained,
but, say, it is n, then, if the figure to be diaardcd
falk exactly midway between two
alternatives, that rounded value shall be chosen which is an integral multiple of 2 n.
For c’xamplc
VALUB
l-75
2.70
3 025
9 075
35 750
:
FXNBNSW or
Ronx~mo
o-5
0.2
50
50
100
ROUNDSD
VALUE
2.0
2.8
30.0 x 10’
91.0 x 10’
35.8 x l(r
Fineness of rounding other than unity in the last place retained would not be generally
required for use in the rules for conversion given in this Guide.
lStncc rcvbcd.
8
3.’ cONVERSION
FACTOti
3.1 The principal conversion ihctors for use in the inter-conversion of dammonly occurring quantities and for calculating other conversion @t&x
of multiple and sub-multiple units and the conversion factors of derived
quantities shall be those g&n in Table I.
TAULY. I
?JtlNU?AL
hhTBxc EQmvurar
NON-METBIOUNIT
I?4
inch
Imp&al
CONVRRSION FACTORS
R~IPBOO~.
millimctrCS ( exact )
O-219 976 Imp gal/l
4-545 96 lilm
gallon
Or
or
4546
09 cubic dccimetrcs*
or
Of
3-785 43 cubic decimetres*
pound
( avoirdupois
dcgrcrt
1.07 I 692’sr/kg
IO4 kilograms
O-555 555 G Centigrade
@264 173 us gal/cu dm
2204 622 lb/kg
0.453 592 4 kilograms
0.933
I srcrt
1 Fahrenheit
)
O-219 969 Imp gat/cu dm
o-264 180 us gal/l
3.785 29 litrrs
US gallon
0.039 370 07 in/mm
degree
~ 1-G dcg F/dcg
C ( exact )
*It should be noted that the latest measurements have revealed asignificant measurabk
dikrence
between the metric capacity unit litre defined as the volume of 1 kg of wrtcr
under certain conditions and the cubic unit of volume of onccubic decimctrc based a
the standard of length mew.
Thus, 1 liter = l*ooO 028 cubic dccimetrc or I_ ml f.000 028 cc.
tThis seer is the standard seer defined in the Standardsof
Weight Act, 1939, asbeing
equal to 14 400 grains. with a multiple unit of maund equal to 40 seers and sub-multiplcp
of 80 tolar and I(i chhataks to one seer.
$In converting temperature values, it should bc borne in mind that zero degree point
on Centigrade Scale corresponds (0 32 degree point on Fahrrnhcit Scale.
3.2 In Appendix A, Table IV, are given derived comersion factors for
commonly used units, such as horsepower, energy, density, weight per unit
/
area, etc.
3.3 More comprehensive
and extended tables have been pubiished in
*IS :786- 1956 which are intended to facilitate the work of engineers, technologists, students and others concerned constantly with tasks involving interconversion of quantities.
*Since revised.
9
ISrm-1956
4. SIGNIF’ICANGE OF GM&
VALUES
4.0 For the purpose of this standard, values in general may be divided into
the following categories and sub-categories.
I Exact Tminating
II
Values
Inexact Valuesfor Exact Quantities
III
Inmut Values Suhjcct to Inhmnt Uncdainty
a) Unqualified Single Num*
Values
b) Maximum and Minimum Single Number Values
c) Multiple Values including Statement of Precision
IV
Dimensional Designation Values
a) Standardized Dimensional Designations
b) Non-Standard Dimensional Designations
V
.
Monetary Values
a) Simple Monetary Values
b) Complex Monetary Values
I
4.1 Exact Terminating Valoes are expressed to as many significant
figures as may be necessary to give the complete value, without any approximation or uncertainty or tolerance.
For example:
a)
100
254
b)
c) 1.728
d)
1.8
e)
100
f)
12
g)
5
centimetres in a metre
centimetres in an inch
cubic inches to a cubic foot
deg F equivalent to 1 dg C
years in a century
units in a dozen
sides to a pentagon
It will be seen that such values generally
conversion factors of one sort or another.
constitute
a category
of
They will thus not require to be converted
to another.
\
from one system of units
4.2 Inexact Values for Exact Quantities include exactly defined values,
pure numbers and conversion factors, which, when stated as a decimal
fraction, have of necessi:ty to remain inexactly stated, but the decimal fraction
represented therein may be carried to as many places as may be necessary
to attain the dtgree of accuracy required for the immediate purpose in view.
10
For cxarnpkz
2
-
~‘3
-
a) losu
o-301 030...
c)
d)
e)
z
e
1dcgF
141421 . . .
- 3.141 59x..
c 2’718 282...
= O-555555... dcg C or
0.556 dcg
f)
1mIKi
-
b)
0.639 370 I...
C
in
As for values in Category II, it will again be noted that such pure
numbers and conversion. factors will not be required to be converted from
one set of units of measurement to another.
4.3 Inexact Vdaea Subject to I&went Un~crtahty include most of
the values representing
physical quantities and certain dimensionless
quantities sGch as percentages and ratios which may represent the result of
a measurement, estimation or calculation.
These may be subdivided into
the three sub-categories as stated under 4.0.
4.3.0 Dimensionless quantities falling in this category such as percentages,
ratios, parts per million, Reynold’s Number and the like rquire no conversion from one set of units to another: they are, therefore, omitted from further
discussion.
43.1
Unqualfwd Sing& Number Values are those which are stated without
qualification as to being maximum or minimum and/or without any reference
to a desired or implied accuracy or uncertainty or tolerance.
For such values supplementary
information
is usually available
regarding the degree of accuracy required or implied according to trade
usage or engineering practice.
Such information should be made use of
in converting these quantities.
In the absence of any guidance as to the
degree of accuracy implied, the accuracy of the value should be assumed to
be f@5 of the unit in the last significant place given.
In applying &is.
rule, however, considerable caution should be exercised to preserve the
accuracy necessary to be maintained in conversion.
For example:
Jn the absence of a clue to the possible or intended accuracy,
a) a dimension specified on a drawing as 0.75 in may be taken to be
accurate to &O-O05 in,
b) a distance between two points on a plan given as 15 miles 3 furlongs
may be taken to be accurate to &O-5 furlong,
c) the tolerance of the length of a battery lead specified as 41 inches in
a specification may be assumed to bc f0.25 in ( see also 4.3.1.2 ),
11
l#:M-1956
d)
a @H measurement
units of PH.
test result of 2.5 may be accurate
to &PO5
4.3.1.1 The underlying
reason for the above rule for the assumed
accuracy of unqualified values becomes clear when the origin of a stafed or
If a higher order of accuracy or tolerance
specified figure is considered.
than that represented by one-half of a unit in the last significant place were
desired or intended, the author of the figure should have either carried the
In the
figure to another significant place or stated its tolerance or error.
absence of any such statement,
the user of the figure is entitled to assume
that the author has given the figure accurate to the nearest unit in the
At the time of origin an adjustment of this type could
last significant place.
be made only to the extent of f0.5 unit of the last significant place, and it is
reasonable
to assume this order of accuracy for figures of this category.
There is, however, one drawback in this assumption,
that most authors,
writers of specifications and designers are likely to drop the zeros at the end
of a decimal fraction, even if significant, and to retain zeros at the end of an
integral number, even if non-significant.
As discussed in the Notes under 2.1
and 2.2 such. practice is contrary
to the recognized practice followed in
Until, however, the recommended
writing f ndian Standard Specifications.
practice of retaining all significant zeros and eliminating
all non-significant
zeros becomes commonly adopted by all concerned, it is essential that this
rule of half a unit accuracy in the last significant figure be applied with
extreme caution.
A brief discussion
this point.
a)
of the examples
given under
4.3.1
will help clarify
It is obvious that the @75 in dimension stated on a drawing without
tolerance could not have been intended by the designer or draftsman
Since,
to be 0.74 or 0.76, for he would have stated it as such.
according to *IS : 2-1949, the values O-745 and O-755 would bc
rounded respectively to 0.74 and O-76 and O-745 + and O-755 would both be rounded to @75, it is reasonable that the designer’s
intention was to imply an accuracy of *O-O05 in his statement of
the 0.75 in dimension.
.
It may be objected that the designer might have stated 0+75
in but meant to imply O-750 in or even O-750 0 in. Such a practice
is not unknown, but it is normal to state a tolerance
when dimcnThe case of tolrranced
dimensions arc intended to be so exact.
sions will be treated later under 4.33.
Furthermore,
according
to Indian Standard
practice, it is recommended
( sre nlso 2.2 )
that whenever a zero is intended to be significant it shall be included
and whenever it is not included it may be taken not to be significant.
Before, however, the Indian Standard
practice becomes
*Since r&red.
12
general1
adopted, users of thii Standard
Guide will have the
responsi x ility of exercising their judgement as to the exact intention of the designer in respect of an untoleranced
dimension, which
intention
will not always be too difficult to ,discover when the
dimension in question is examined carefully in respect of its signiticance and importance
in relation to ,other associated dimensions
and to the context.
b) A distance of 15 miles 3 furlongs indicated may be the result of a
measurement,
in which case it is clear that the figure of 3 furlongs
is most likely the result of rounding off the measured distance to
the nearest furlong.
Thus, the presumption
of f0.5
furlong
accuracy may be quite justified.
But, if this distance is given
on a construction
plan where the two points in question are to
be located by measurement
in the Eeld, then under present-day
practice the accuracy intended for this measurement
would naturally be that attainable
by the usual method and equipment
employed for measuring off this particular
distance.
That is to
say, the accuracy
implied would be much better than fP5
furlong; it may be f one yard or one foot, or sometimes
even
better than that, say fone
inch,, depending
entirely on the requirements
of the job concerned.
In such cases, it must be
realized that the dimension
in question cannot be taken strictly
to”belong to this category of unqualified values but may be classed
in the category of precise dimensions discussed under 4.3.3.-
4
The 4) in length of battery lead called for in a specification may
safely be taken to be between 4i and 49 in because it will be
recognized
that in practice a 4 in variation
up or down is not
going to make the battery
difliculr of assembly or use. But,
then, if the dimension for such a lead is specified, say, 4 in, we shall
have to be careful in assuming its permissible
variation
to be
f + in.
Therefore, &we is considerable room for caution in the use
of this peral
rule even in cases of relatively unimportunt dimensions.
In general, it is recommended
that for vulgar fractions directions
given under 4.3.1.2 may be followed.
d)
In case of a statement of a result of measurement
such as the PH,
chemical composition, strength of a test piece, etc, there is usually
little danger of going wrong.in
assuming the order of accuracy
recommended
here.
This is so because reporting
authorities
are
not prone to state the result of a test in fewer numbers of significant figures than actuaily obtained by making a measurement
or
as may be derived through calculations based on measured values.
They are, on the contrary, likely to state more significant figures
than may be actually justified by the accuracy of the method
used.
13
Ir787-1936
43.1.2 In case of vulgar fraction values, particularly for inches, it is
not ulwuys possible to assume the accuracy to be &i of the fractional
Vulgar inch fractiona
Ft of the value as explained in example (c) above.
m general are known to imply a much higher degree of accuracy th .n this,
of
but the order of magnitude
of the accuracy depends mostly on the
For example, if a directive required 4) in b lX
dimension involved.
be cut ofT from a rod for further machining,
it certainly implicm a high:
degree of accuracy than # in as may readily be im uted to a battery lead
In all cases of vu Pgar fractions, therefore,
length of example (c) above.
before proceeding to convert a value to metric or other units, it ,is advisable to
convert the vulgar fraction in question to a decimal
fraction first and
express it to such number
of places as may be considered
adequate
fo
express the degree of accuracy appropriate
for the particular job in hand*
For example, the 14 in blank for machining
may be taken to be l-5 in so
that its implied accuracy is f0.05 in.
According to *IS : 696-1955 an unqualified vulgar fraction dimension
on a drawing may be taken to be accurate to &-& in. This may serve as a
suitable guide in most cases except where a dimension
is carried to a44 in,
Influence
A divension
carried to s’p in may also sometimes lead to doubt.
of surface texture on attainable
accuracy should also be borne in mind.
In all such cases, therefore, the above rule of converting the vulgar fraction
dimension to decimal fraction and ?z.t.sigtlitrgit the apflojriaie precision before
conversion will be found most useful ( see also 4.33 ).
In converting vulgar fractions, the use of TIg : 5-1949 will facilitate the
work of obtaining
exact decimal equivalents
of vulgar inch fractions both
in inches and millimetres.
4.3.1.3 Conversely, the above rule should also be adopted in specifying
a value or reporting a test result without tolerance limits or estimated error,
when care should be taken that only the last significant figure is in doubt to
the extent of not more than f0.5 unit in the last significant place, and,
further, that all significant zeros should be retained and all non-significant
zeros dropped.
4.3.1.4 Assuming that in stating the unqualified single number values,
the practice recommended
under 4.3.1.3 has been followed, then the maximum and minimum limits of relative or percentage
errors of such valum
become a direct function of the number of significant figures retained in
the value.
On this basis, the range of percentage errors to three significant
tigures will be within the limits given in Table II.
4.3.2 A4aximum and Minimum Single Number Valws include specification
values, values expressing result of an experiment, expectation of an operation,
limit, capacity or possibility of achievement,
etc.
*Second revision in 1972.
tSince withdrawn.
14
M UNQUALRlRD
(&xr#
Nmarr,
of
SlOlWXlAWT
F”s~*
4.3.1.4)
RURo8 OI
sloyo”AW&ABTx
LxYrn
u
1
I(4
2
10 ”
99
3
100 ”
999
4
5
n
1000
”
10000 ”
10s - I ”
9
o* _Pn~WrAO.
c--A--%
Maximum
Minimum
50.0
5.56
5+0
0.505
O-500
o-050 I
9999
0.050 0
O-005 00
99 999
0.005 00
o+oO 500
IO”-1
5 x I@‘”
5 x lo’-“+
*This expression applies to larger value of n; for all values including smaller values
of IIthe general expression for minimum
percentage error will be 50 + ( 19 - I ).
In some cases, tolen nce limits or uncertainty
of estimates are sometimes
found associated with maximum and minimum values, but really they can
have no significance and, as a general rule, should be avoided in stating such
values.
For instance, there is no point in stating that the minimum tensile
rtrength of steel shall be 30 & 1 tons per square inch, or for that matter
ss 7’: tons per square inch.
It may be noted that a single value statement
of 29, 30 or 31 tons per square inch as the minimum strength, depending
on the actual need of the situation,
will be much more appropriate
and
unambiguous,
for it will cover the full significance
of the requirement.
For the purpose of conversion
of maximum
and minimum
single
number values from one system of units to another, it is important to determine beforehand whether the number of significant figures appearing in the
stated value adequately
expresses its precision or whether the method of
measurement
expected to be employed or the character
of requirement
intended to be imposed would normally require additional significant figures
to be added to the value to achieve the requisite degree of precision in the
stated value.
If such be the case, an additional zero or zeros may be added
to the stated value and considered significant for the purpose of conversion
( see also Notes under 2.2 ). For example, the 30 tons per square inch as
minimum tensile strength may imply an accuracy of only f @5 ton per square
inch, if a very coarse determination
was involved, in which case the two
But such a position
significant figures of 30 would suffice for conversion.
will be exceptional since it is customary to measure tensile strength of metals
of this order of magnitude to a greater degree of precision and, in most cases,
tensile strength specifications
require compliance
to a specified value to a
larger number
of significant figures.
The usual practice is to determine
nearest
100 lb or the nearest
tensile strength
of this order to the
15
IS*78791958
hundredweight.
Thus,, the original value of 30 tons for the purpose of
conversion
may be taken to mean 30% tons per square
inch, with an
understanding
that its precision is of the order of kO.05 ton per square inch.
4.3.2.1 In all Indian Standard
Specifications,
a general practice
been adopted to include in their Forewords the following paragraph:
has
“For the purpose of deciding whether a particular requirement
of this standard is complied with, the final value, observed or calculated, expressing the result of a test or analysis, shall be rounded
off in accordance with *IS : 2-1949.
The number of places retained
in the rounded off value should be the same as that of the specified
value in the standard.”
The intention of this paragraph
is that the precision of values such as
those discussed under 4.3.1 and 4.3.2 shall be automatically
implied in the
stated values in Indian Standard Specification.
In respect of all such values
specified in Indian
Standards
carrying
the above quoted paragraph
in
the Foreword, there is, therefore, no,need to give any special thought to their
possible or probable precision, since th% .have originally been stated with a
view to comparing
them *with the test results .af& the latter have been
rounded off. Thus, their precision is implied to be kO.5 of the unit in the
last significant figure.
4.3.3 11Iult@e ,I’umber. Vuiue.chcludirlg Sta.kment of Precisiot~, such as tolerance limits or errors of determination,
include most precision dimensions
specification
values requiring
close inspection
on engineering
drwings,
limits, results of accurate measurements,
etc.
The precision of such values may be stated in any of the ways illustrated
by the following examples:
a)
Weight
b) Grind
c)
Internal
of cloth shall be 12.2 to 12.8 oz per square
the
plug
diameter
d) Distance between
c) Acceleration
due
was 32.191 05 f
f) Weigh about 1 g
to
1.2 z:g
yard,
ii in diameter,
of the collar shall be li zi:E
2 in,
centres of two holes shall be If rtO.015 in,
to gravity as *determined
in the experiments
PUOO 02 ft per second per second, and
of the composite sample accurately
to 0.1 mg.
In each of these examples while the precision and, therefore, the limits
of variation of the main value have been explicitly s&d,
the precision of the
related tolerances or associated error of errors themselves is not apparent
in
or the variation
of limits
each case. The precision of the tolerances
determines the-interchangeability
of parts and depends on the .method of
measurement
employed or intended
to be employed in manufacture
and
*Since rcviscci.
16
.
I8:787=19!i6
inspection*. It is im rtant, therefore, that the precision of the tolerance
limits be assessed be p”
ore conversion of such values is attempted.
4.3.3.1 A brief discussion of the above examples will illustrate the type
of decisions that may have to be made before conversion of such values is
attempted:
a)
Weight of cloth 12-2 to 12-S ozw sqyd-;The
accuracy of the method
of measurement in this case depends on both the measurement of
area and that of weight.
It may be reasonably assumed that the
accuracy of @05 oz per sq yd implied in the statement of this
value is adequate, yet the usual method of measurement involved
may be able to give a better accuracy.
In certain cases, it may be
desirable to investigate the question to ascertain the limiting accuracy of such values by referring to appropriate standard method
of test such as the Indian Standards on the subject.
In this
particular case, a reference may be made tobS :‘242-195 1 Method
for the Determination
of Weight per Square Yard (or Square
Metre ) and Weight per Linear Yard ( or Linear Metre ) of Cotton
Fabrics, together with the associated standard $IS : 241-1951
Method for the Determination
of Cotton Fabric Dimensions.
From these standards it will be seen that weight measurement is
required to be accurate to 1 in 500 or, sap, to O-2 percent and the
length measurement
to fO*5 in, and width to -+A in. The
two latter figures when applied to a minimum size of piece of,
say, 10 yd x t yd lead to a maximum
error of about @4 percent in area determination.
Thus, the weight per unit area result
is likely to be uncertain up to O-2 + O-4 or 0’6 percent.
In
case of our example, this implies an error of about #OS oz.per
sq yd, which is of the same order of magnitude as the usual pr+
sumption of one-half unit of the last sign&ant
figure, namely
f0.05.
In such a case, the 12.2 to 12.8 value may, therefore,
be used as such for convuJion with an implied accuracy of-k&05.
In other cases, it is q&e likely, particularly where practice
followed in Indian Standards is not followed, that in specifying the
original value account has not been taken of a bigher degree of’
precision attainable in medsurement.
In such cases, it will be
justified to rewrite the valuie to more than the given number of
‘significant figures, before COnversion is attempted. Thus, in the
above example suppose the estimated error of determination bad
-For more detailed diion
on this subject, rcfcrcnce is invited to :
ADAMS, G. C. Principb and Practice Coveming Intcrchangcability ihd Specification
of Manufacturing Limits d Size, aa Influenced by Statistical Considerations. Pmt. (A) ht.
.WecR.Ems., Vol. 167 No. 2, pp. 154-169 ( 1953 ).
tSuperudcd by IS : 196+1970 Methods lbr dctcrmiMtion of weigh pa qu8le laetrc
aud weight per linear metrc of ~brics (fir ti
).
$%apcruskd by IS: 1954-1969 Methods for determination of kqtb
fabrh (@f f&&a ).
17
attd width of
come out to bc *001
oz per q yd i~t~d of OO~Sthen *Cvalue should be rewritten as ‘ 12”20 to 12.80” for the purpose of
convcraion.
b) Plug 13iametcr:
~.~ +“@07
in
--O@OO 56
c) Collar Diameter:
1# ~.”&#
z
d) Hole Distance:
1~ &O”O15in
c)
the number of decimal pla
of fictions will be the sam
to include the implication
in
For exampIe:
i) llz~ -& 0“002 in sha
though actually I#i
ii) g: +0”01 in shall b(
aCtUally $1 =
that
the precision or a stated tolerance maybe
taken to be +5 perCCnt
far tolerancm 0“001 in or C~
~d +Om
05 m for tol_
Sner than 04M1 in. Thus in rew”ting tokznw limits for inch dimen-
kn for conversion purposes, it will J7.@ce to aali one zero to all toknce$
o ant magnitude having one signt@ant J@e, ~o~d
~ zno is U
L!!
gond t~ j>h place of decimal fraction in inches. Thu
oceduw &o
implies that the converted values need not be roxndeJ“ to a Jaeness
closer than 040005
in or 0“001 mtn. Simikrly for rewrilin rniflimeiru
dimensions. for conversion, one sign$cmd zero may be addef t? all oa8
3i@icant jigure limits, prooided no zero is aaW beyond the tlurd pke
of decimals. No change need be made in rewriting tolerance
limit va[uc$ of 2 or more significant iigureB whether they are in
inches or mil!imetrt%
Thus, for the purpoze. of conversion, valuu typified by thc
dimensions in the examples given under (b), (c and (d) should
ix rewritten so that the number of deeimal pL ces in both the
main dimensions and in the tolerance are the same thux
Mug Diameter:
1020000
~.&
18
‘J
in
().578
Here again, as elsewh(
rounding off purpm~.
e) Acceleration due b gravity:
b
As already stated elsewher
In normal engimiering practice, for tole0“001 mm ( i micron).
rances of 0-001 in or coarser, accuracy of measurement to ensure
interchangeability may be taken to be + 4 percent, and for tolerances finer than 0001 it maybe taken to be 000003 in unif-y.
In terms of m&ric units this means an accuracy of k 4 percent for
tolerances of’0-025 mm or coamer and *04M08
mm for tolerancca
tier than O“ofxmm ( see0.4).
k w recommended
1’37500
1“750
In applying this rule t{
I
e of this Standard (hide
Diameta
d) Hole Distance:
These three cases may be dealt with together for they are all
concerned with precision dimensions intended to ensure interchangeability of parts. In ,practice it is possible to confirm to such
tolerance limits only within the accuracy of the method of dimensional inspection adopted, whether by limit gauging or by direct
The highest precision to which best tool-room
measurement.
practice may extend in India would be about 0“000 05 in or
For the pu
C&r
this exprewing experiments”
cision of both the main val
be adequately included in i
f)
Weigh about I g accurate~ to
may, for instance, be 1’013 !
*0”000 1 g. This exampl
.r~ult and may be treated a
4.3.3.2 In order to avoid errom
some cases are likely to be aggravate
that before converting multiple numt
sion, the main values and the toleranc~
values. Thus, the examples discusse{
follows bdorc actual conve~ion is ma{
a)
b)
c)
12”2 to i2”8 02 per sq
1’20007 and 10199~“
1“37800 and 1“374 ~
d)
i)
ii)
c)
f)
1“765
1“2208
0“588
32-19107
and
and
and
and
1“735 i
]“2]6 ~
0’568 i;
32’191
1-0136
and 1“0]34
since it is generally preferred
to
workshop practice,
the converted
din
~
*Smcc revised.
19
.
bb:767-1959
+O%lO300.
collar Diameter: 1.375 00 dO9O 20 m
I.750
f0’015 in
Hole Distance:
In applying this rule to vulgar fractions, it ‘may be noted that
the number of decimal places to be retained in the decimal version
of&actions will be the same as that in the tolerance limit rewritten
to include the implication of its accuracy.
For example:
i) l& f 6002 in shall be rewritten as 1.218 8 fOW2 0 in
though actually l-& = l-218 75,
ii) H -J$POl in shall be rewritten as O-578 fO*OlO in though
actually a = O-578 125.
Here again, as elsewhere, *IS : 2-1949 shall be followed for
rounding off purposes.
32.19105 f0’6OO02ft@rsccpsrsucAcc8&fation da9 to grati&:
As already stated elsewhere, it is quite safe to convert values like
this expressing experimental results just as they stand, for the precision of both the main value and the error may each be. taken to
be adequately included in the statement.
Weigh about 1 g uccuratdy to 61 mg - The result of such weighing
may, for instance, be 1 *013 5 g whose accuracy may be taken to be
+M60 1 g. This example is of the nature of an experimental
result and may be treated as (t) above.
4.3.3.2 In order to avoid errors of addition and subtraction, which in
some cases are likely to be aggravated in conversion, it is further proposed
that before converting multiple number values including statement of precision, the main values and the tolerances ( or errors ) be expressed as limiting
values. Thus, the examples discussed under 433.1 may be rewritten as
follows before actual conversion is made:
.
12.2 to 128 oz per sq yd
a)
I*200 07 and 1.199 44 in
b)
1.378 00 and 1*374 80 in
c)
1.765
and 1.735 in
d)
1.2208 and 1.2168 in
i)
ii)
6588
and @568 in
32.19107
and 32.19103 fi per set per set
e)
1.013
6
and 1.013 4 g
f>
Since it is generally preferred to use the limiting values as such far
workshop practice, the converted dimensional values may be left in the
+siaecm?llal.
19
ls:797-1956
form of limiting values. But, if tolerances ‘or errors of converted values in
terms of new units of measurements are desired, they may be derived Corn
the converted limiting values by simple subtraction and the results expressed
accordingly.
4.4 Disnes~~ional DesignHi& Values are really not values in the strictest
sense of the word but merely labels which designate the type, class or category
of objects, articles or materials. Such designations may be divided into
two sub-categories, namely (a) the Standardized Dimensional Designations,
and (b) the Non-Standard ( or ud hoc ) Dimensional Designations.
4.4.1 Stanaizrd&d Dimeasional Desipatiotri are ,$10gt which are recognized
in current standards and are employed in common usage.
Designation values normally correspond to one of the dimensions of the
article or object designated, but the article or object is not necdly completely defined by it; it may require several additional dimensions and
attributes to define the article fully. In certain cases, standard dimensional
designation does not represent any dimension of the article or object it
designates. In most cases, the designation dimension corresponds only
nominally to one of the actual dimensions.
Exam,6les!
4 8 x 4 itz Standard I-beam has a depth of 8 in and a flange width, of
4 in, but to define it completely the thickness of its web and ilange
and sometimes also the slope of the flange are to be specified.
If, in addition to the shape of its cross-section, one is interested in
the material, it will be required to indicate whether it is of ordinary
structural steel, high tensile steel or something else.
b) 6 in-ltyt ring bobbk has none of its dimensions corresponding to
anywhere near 6 in. Here the significance of 6 in is that the ring
spinning machine on which the bobbin is used has a lift of 6 in
and, therefore, the yarn wound on the bobbin is spread over it
to that extent.
2 in welded s&e/pi& has neither the inside nor the outside diameter
equal to 2 in, though they are both close to it. In this class of
pipes, while the outside diameter for a given size designation may
be fixed, the inside diameter may vary depending on the wallthickness for which severalchoices are available.
16 it1 table-&@ electric fan has a blade sweep of 16 in, but its service,
4 characteristics
in terms of air-delivery, energy-consum tion,
safe speed, etc, are the really useful attributes which d e&e it
more logically ( see *IS : 555-1955 Specification for Table-Type
Electric Fans ).
*&xoad r&siom
in !967
20
*
ifst -m= ?.2::.2
1
e)
1
i
IS Sieve 30 indicates the Indiaq ,Standard Sieve having openin~i
approximating to 30 x 10 or 300 microns, although the CXZC<
size “of openings n required “to be 296 microns within
for Test si~v~~ ).
tolerances (see *IS : 460-1953 Specification
The British practice of specifying sieves is in,. terms of so many
openings per inch length, thus a 52-mesh Brltlsh Stanckrd Sieve
s~ec&.d
t
Y
which
Q
corresponds
have 52 openings
i,
approximately
per linear inch
But the number 52 by itself is not
to IS Sieve 30 is irlte]?d.c:~ :V
, h weft-ways and warp->vz:ys.
aT all indicative of the (jp~iaii~l{;
dimension
of the sieve, namely the opening,
because the ‘,;irr
diameter has to be known before the opening can be talc-ulatcd,
d
f)
e
18-8 Chrome-nickel stiel designates
containing
18 percent of chro-mium
the varietv , of stainicss S:C: !
and 8 percent of nic!ici \$itiiii;
specified tolerances.
of
Its exact chemical composition and sta~c
heat-treatment,
however, have to be specified
for ~ fu]]cr d(,:,cz~z,.
1-
d
d
it
Iy
tion.
if left alone in the {;L-iL;;,-i;:;
4.4.1.1 It is obvious that such designation,
form, cannot interfere with engineering operations such as are iII.Irii:.!!;.
revolved m design and construction of machines and structures, nor c;m s c!:
J.,
practice lead to misunderstanding or incomplete comprehension.
.~lcttl..>’~,
as ]ong as the article or object continues to be manufactured ill c,>llfol-;::i~;,
with prevailing
standards,
the retention
of the current desi;<rl ations .,,,.:“’”,:
help to avoid confusion,
The specific dimensions defining the ai-ticlc
of
XC
d.
i
object in detail, however,
may require
to be converted
for cer[ai:i p~rpc~:j,
When a current system :’f units of measurement
in a given ~::dm:r!,-,
.
.
trade or nation undergoes a change, It M to be expected that, dur!ns ii];
changeover period, standardization authorities concerned wi]i f~ri~~~~ !;.:c
.
.
standards for articles and objects ]n which the ,governmg dlmeris]ons
give rise to the designation
of the objects ~ri]] a]so
be
s~andas.di;:c~
~,1
~,luti~::
unip.
When such standardization
is carried out, it should be pos:~b)c c,
cteclde what new designations should be devised.
SUCh new CIeSi:rjaI.i{,:LI:
may be m the new set of uruts or may be entn-ely free from any unit of
measurement, For example, as long as the present 8 m x 4 in I-beams m:<
~ in flats are produced in the country, the~e should be no objectioi~ to the
statement: “ Cut offs 5“71 mctre length of an 8 in x 4 in I-b~..,~i ~~~d
strengthen it by the addition of 2 flats, & in x 4 in and 5“50 mctrcs l17i?CJ tU
the flanges “. In case, in the future, standardization
of production in steel i~
in
ry
.
.
-,~~aitii
io
ng
in
it
ter
of
lay,
111-
enforced
in metric
units,
the corresponding
statement
may be: “ ~t~ t
o:T
v,
5-71 metre length of a 200 x 100 mm I-beam and strengthen it by acidin~
two flats, 15 mm x 100 mm and 5-50 metres long to the fianges “.
icc;
on,
; it
fpe
in
4.4.2 .Non-standard Dimensional ,Designatiom are those which are
engineering practice or trade for convenience of operations within limited
spheres of a company, factory or workshop, but they arc not covered .bj~
TISCG
national
or international
standards
nor are they found in general
-USC.
*Since revised.
21
-,
..,-.
“?H”.
!4
#
.,4
c
,
-’!
.“
I,,
/
.,
.“i;.
f..
Pl787-lma
For aKamplc?z
4
W
Cl
4
8frl&mGmtcirclrsintauledtbrutensil~daignatca
adteafbknhunongrcvarldzaprepPledinafoctoryforfivtha
processing.
12x9f)Mircqpurc~~tisanesizeof~~rrmang~
available in trade, but normally there is no hard and tit rule to
limit the choice of carpet !&a [ SM *Is : 433-1953 specification
for Handloom Carpets ( Mirzapur ) for Export].
) in stuf tit for uac in tumbling opcrationa in a. foundry.
2 in blunks for fin%hcr machining.
4.4.2.1 It ia advisable that non-standard designations of this type
should be convcrtcd to the new se4 of units when associated dimenaiona
are being convcrtai. In doing ao, it is desirable to consider how far they
may be rounded oifto a convenient number. This ia an individual problem
to bc decided by the company or .&e mahagcmcnt of the factory concerncdl
For example, an 8 in ahuninium circle may bc convcrtcd as 20 cm circle
oritmaybcnccegarytokecpitat20’3cm(orevcn2032cm)d d i n g
e coluicntircly on the requirementa of fiuthcr pnxafsing. Similarly, Gfen
derationa will dictate whether a 12 x 9 R carpet be rcchipati aa
4 x 3 metrcs or 3-7 x 2.7 metres or 9 square metrcs or simply tie i, or
y, or z. Sii remarks apply to examples (c) and (d) unda 4.4%
In caaca whcre_additional information is not available or job requ&
meats arc indctammate to guide conversion, the non-standard dcsignatioa
may bc treated as unqu&ficd single number values d&sscd under 4.8.1.
4.4.3 It muat bc -cd that o&aaions may ax+ where the distinct&
bctwecn the e and non+tandard dimensional dcsignationa may
not bc clear-cut or &dent. In 8uch casts, it ma lx useful to study the
probkminsomedctailbcf+edccidingtheisduewhe 3:atoconvcrtornotto
convert, and, if it is decided to convert, how far to round o$.
4.5 lldopctur Values include simple *values involving amounts of money
exprared simply in tams of rupas, arm& and pier, and complex vale
involving prices, rates, tar%%, wages, duties, discounts, in-t, taxes, etc,
in which monetary quantities arc liikcd with some other umta of muuure,
Under the Indian Coii ( Amendment ) Act, 1955, the Indian
rupccistobcdividcdinto1OO‘Poiss’.
Thuat!x~andpics@theoriginal given valua will need bc converted to dm form involving new
c&encyunitsofrupccsand’Pakr’.
Ordinarily, it should lx possible to treat all monetary values in-the
same manner as the inexact values discurecd under 4.3 and
e 091,
larly 43.1. But since the smallest monetary unit is one ‘ P&u ’ or fr”“”
thchafra;udirrgf~&~
withducrqpuitothcpracticaI
~~~ofmoney~~t8keplaaintunnofasmUcr,hction
&ItthatIrnotto~ythrtafineneaofroundrnsfina
;thiSWillbCrCmlhmthCdi+
tlunOQlofaru&will-be
cuhn under 45.2 dealing with
4&1shl#laM~valufs~simplestaturun bOfgmOUIltSOfmoaty
withoutanylinlugcwithaQotherunitofmerwrr.
For acamplc:
a) Gratuity due to A is Rs 40018.
b) B owes C a sum OTRa 4514.
c) ~tcvalueofsharcsownedbyDincludingthc7pcrccnt
divrdmd due next month amounts to Rs 359/8/3.
d) E’a contribution was Ra 1001.
Convarion of sim le monetary v+s involva da+ahza tion of the
given values and roun x1‘ng olT the daxmalkd values to a lineneas of 091
of’s rupee or, say, to two placea of decimal. It is natural that some of the
converted values will not require any roundii off bccau8e theymay lead
touract decimaLed fkctions involving only two or even less places of
da&al, but all of thcsc should be carried to two places for the sake of clarity
ofexpression.
,
For acample:
Dtdmalkd Volys
-Volvc
Giorn V&e
400.5
Rs
40050
. Ra 400/r,
Rs
4925
Rs
45.25
4514
Rs
35952
359515 625
Ra 3591813
Ra 1 ool*OO
1001
Rs 1 OOl{l
45.2 Com$cx Mcne&w~ +alnes involve more than a simple statement of8n
amount of money; they arc in the nature of a rate, that is an amount of
mouey associated with some other unit of mwurcmcnt.
For acamplc
a ) Priceoforangcs
b) wywyla
c ) DilMxluntrate
d) Rateofintcrest
e) Rental
f ) salataxonclotll
g) Roadfnight
h) -duty
Re -{8s/- a dozen
h~ WP per day
Re -{316 pa: r u p e e
Ra S/66/- percent
Ra 391314 per acre
Re -/2/- per 100 yah
Re -1-14 per mile
h lo/-/- pa maund
monetary values
It will be seen that the above cxampla of corn
may be broadly divided into two’general categorks. fP
efirstfburexampk8
represent valuea linked with units of measure, such as numbar, &ne, currency, and percentage which latter in themaelvea do-not require any converaion. The last four exampla on the other hand are linked with nonmetric units of measure, such as acre, yard, milt and mound, which may
need be converted to metric units. Thus in the first category of such values
only the decimalization of currency is rquired and in the latter category,
beaides decimalization of currency, conversion in terms of the associated
unit in the given values to a new set of physical units is also required. In
both of these cases, however, the choice of fineness of rounding is a complex
matter and not as simple as in the case of aimpllt monetary values disc4
under 4.5.1.
,W
The choice of fineness in these cases is complicated, because a complex
value represents a rate which is used as a basis for calculating the amount
of money that may have to change hands, and it ia this final amount which
is capable of being rounded off to the nearest one ‘ Puisu ’ or 001 of a rupee.
Thus-he choice of timmesa will depend on the particular application in connection with which the rate represented by the given complex value is to k
used; If a rate is normally to be used for division, for instance a rate per
ton used for determining price of a few pounds, then the fineness of roundmg
can be the same as in case of sim le monetary values ( so 4&l), namely
one ‘ P&a ‘. On the other hand iPmultiplication is involved in determining
total amounts on the basis of a given rate, then the fineness of rounding off the
converted’rate will depend on two considerations:
a) taEdmagnitude of the maximum multiplier that may be envisaged,
h) the minimum monetary unit to which the final payment need be
rounded off.
4.5.2.1 An excellent example illustrating these considerations is furnished by railway fare rates. The rate i&elf may be stated in terms of
pies or annas per mile and made applicable to a transport system the maximum haulage distance of which is known. Further, the fm between
given points may be rounded off to one anna after being calculated for
each pair of stations involved. In case of air fares the rounding off ma be
to the nearest rupee. It is thus clear that the fineness of rounding orthe
converted fare rates could be determined, if the maximum distance to which
the fare rate is to be made applicable is known and a de&ion is taken as to
the minimum monetary unit to which fmal fhres will be rounded off. More
spe&cally, consider the following example:
Giom:
Fare rate
Maximum distance involved
.
24
==Qpiespermik
==126omiles
u n i t fm
rounding off the point-to.
point&rcs
Present
Future
Minimum monetary
=lanna
= 5 ‘ Poise ’
&%dutk
SpiUpadC
r Re O-015 625 per mile.
p: Re CO15 625 x O-621 371 per kilometre
= Re OW9 706 266 per kilometre
1260 miles
PI 1 260 x’ l-609 kiIometres
~‘2 000 kilometres approx
‘5
RcO-05~2000
QI ReOWOO25
.*. fineness of rounding
P ReO-00001
:. converted fare rate
= Re O-009 71 per kilometre
4.5.2.2 It must, howcve,r, always be borne in mind that it may not
alw8ys be nccusary to be absolutely exact in converting a rate, bccawc
there are so many fmrs that go to determine a given rate and many of
thacf&orsarc constantly being a&ted by economic and other conaiderations. There is thw nothing in the nature of a mathematical u$ctitude in
any of the market rates which fluctuate all the time. Once they begin to be
quoted in terms ofpew currency and new units of measurement, no conv&on problem need arise. Even in case of taril% and !Iues, slight adjwtma10 are always pomible. For instance, if in the numerical example
given under 4.5.2.1 the converted fire rate was rounded off to second place
of decimal iwtead of the 6tIh, i.e., Re @Ol per kilomctre, it would mean
over-charging the travcller nomething leu than 3 percent ofwhat he may bc
p8ying before conversion. Administration concerned may find that this
unount my bt conridaad just&d because of some new f&Sty recently
made available to travcllers, but which, if required to be charged for under
eilsnditiow, would invdve an unjwtifiable amount of rcadjwtmcnt
.
Thus it is clear that in converting complex monetary values, each
should he indh?idually examined for tl& purpose of detcrminiig the appropri8te6nenaofroundingofftheconvated vahu.
25
5. PROCEDURE FOR CONVERSION
5.0 It has been clearly brought out by the dkwsion under 4 that the
significance of values as used in engineering and trade prac$ces
on the context in which they are used and the urpose they are inten
ed$~
Y
serve. The modl of usage and the manner of! expression of a given val&
determine, to a large extent, the associated accuracy of the values which
must be carried over to the converted value. Even where tolerance limits
of a specified value are &ted, it is essential that in order to ensure interchangeability of parts made to such tolerances, carefkl consideration be
given during conversion to the associated accuracy of the tolerances themselves, which accuracy in turn depends upo? design requirements and the
manufacturing precision and inspection techniques employed in production.
It is important, therefore, that instructions given under 4 should be
carefully studied before the rules for conversion given under 5.1 and 5.2 are
used for actual conversion. In Appendix B are summarized the conclusions
of this discussion to assist in rewriting given values before conversion.
5.0.1 To facilitate the statement of the rulcs,monetary values of category V
( SIC 4.5 ) have been separately dealt with under 5.2, while values of categories
I to IV ( set 4.1 to 4.4 ) are covered under 5.1.
5.1 Rules - Keeping in mind the precaution discussed under 5.1.2, the
rules to be followed in the conversion of given values of categories I, II, III
and IV from one set of units to another shall be as follows:
Rule I- Classify the given value according to categories discussed
under 4 and examine its significance in the light of the discussion under
appropriate category.
Rule II - Rewrite the value, modifying it, if necessary, as directed
under 4 ( see also Appendix B ).
Rule III - Choose an appropriate conversion factor from those given
under 3 and in Appendix A, and round it off, if need be, to appropriate
number of decimal places for the particular conversion in hand. It is
generally adequate 10 retain in the conversion factor two more significant
figures than those appearing in the rewritten given number.
NOTS - To convert a value expressed in derived units, do not use more than one conversion factor in repeated operations, but select such a derived conversion factor from
among those given as will require only one arithmetical o eration, preferablymultiplication. If such a factor is not readily available. it may !e calculated by using the
principal conversion factors or other factors from the given list.
This procedure is recommended to reduce the chance of avoidable error aml to save
time in calculations.
For example:
A pressure value given in tona per sq in should not be converted by first multi lying
by I OltiO5 to convert it to kg per sq in and then dividing by 645.16 to obtain Pg per
26
1
Irnt&,&zuudingtothisrule,theeon~v8laerbaold bcdbbincd
z!!; by using the t&tor.
/
1 tonpcrsqin- 1.5749kgpcrrqmm.
Sily, to convert 8n uca v8llle given in aqu8rc indK¶ illto 8qlmrc cult~ctra#
multiply directly by 6451 6 and not by 2-54 twice.
IUI IV- Convert the rewritten value by using the selected or
calculated conversion factor and carry out the convezsion to at least tm,
more significant figures than in the rewritten valte.
Rule V - For rounding off the converted value, decide the fineness of
rounding as follows:
Write down the significant part of the rewritten original value for
using it as standard of comparison. Call it So.
b) Write down the significant part of the converted value and drop
from it one figure at a time until the significant part assumes
for the first time the same order of magnitude as S,. Call this S,.
C> Drop another sign&ant figure from S, and observe that the
resultant value S, also has the same order of magnitude as S,..
d) Of S, and S,, choose one as S wl$ch bears the least ratio to So.
That is
a>
so
’
if $>!$‘,chooseS,asS
If S, contains inly o:e significant figure, obviously S, shall be
taken to be S.
4 The fineness of rounding should then be taken as unity in the last
place retained in S.
To ensure interchangeability of machined parts, the fineness of-rounding for linear dimensions need not be finer than 0.001 mm or O*OOO 05 in
( .%?I? 4.3.3 ).
Rule VZ - Using the fineness of rounding thus determined, round off
the calculated converted value and retain in the final converted value all
the significant zeros and drop from it all the non-significant zeros.
NOTE - In case of kfdtiple Number Values including statement of precision, th’e
tolrranccs of errors in terms of uew units of measurement may be obtained, if de&d,
from the converted limiting values.
5.1 .I Examples - A few examples of the application of Rules of Conversion
specified ux$er 5.1 are given in Table III in which the procedure of conversion is also Illustrated.
5.1.2 Precaution - The rules given under 5.1 have been designed to ensure
that the accuracy of statement or the significance of a given value is reflected
in the converted value as closely as possible within limitations imposed by
the operation of conversion. It will be seen from Table II that an unqualified
27
’
DIl967.19S6
single significant figure value is subject to an error of 5.6 to 50 percent and
a two significant figure value from 0.5 to 5
nt and so on. Thus, on
conversion, one and two significant figure vap”’
ues are likely to be subject to
errors of similar orders of magnitude.
But then, if such original values are
rewritten in the light of context and the number of significant figures in
their restatement is increased to the extent justified by circumstances of
the case, then the converted values would automatically reflect the order of
accuracy desired to be expressed.
For example, a linear density of 1 lb per ft converted as such into
metric units, according to the above’rules, would lead to an answer of 1 kg
per metre. The conversion fatztor being l-488, one may well say that the
error of conversion is 48.8 percent in this case. It may be noted that the
error of statement of the ori inal value as it stands is actually 50 percent
( SM u&o 4.3.1.4 and Table If ) and, therefore, the error of 48.8 percent in
the converted value is not greater than that of the original value.
Now, if in the light of context, we could rewrite the given value as
1.0 lb per foot, the converted value according to the above rules would be
15 kg per metre. The accuracy of statement of the original value is thus
enhanced to 5 percent and that of the resulting value to better than one
percent ( see also example 11 in Table III ).
5.2 Monet8ry V&sea - With due reference to the significance of the two
categories of monetary valub discussed under 4.5, the rules to be followed
for their conversion shall be as follows:
Rule VII - For simple monetary values, decimalize the given value and
mund off or carry to two decimal places in terms of rupees ( or to one ‘ P&a ).
Hulc VW-For complex monetary values, decimalize the given
value and convert it ‘in res
t of the &so&ted unit of measurement, if
, determine the appropriate fineness o< rounding
necessary. For rounding otp”
in relation to the use to which the converted value is $0 be put.
NoTls - In selecting n~uitahle conversion factor for use in converting monetary values
-bated with convcz&ible units of maaurement, do not select a factor which involves
either a multiple operation ( $18 Note under Rule III, in 5.1 ) or OIIC which involv~r
a division. The reciprocal conversion fat. .a r;iven in the last columns of both Tables
I and IV arc the appropriate factors for this ,J~~+I+, which should be used.
For example:
To convert the value Rs 11/8/- per rquare yud, & rwl uw either of the following
factors ( Table IV )
1 yard - @914 4 metre
1 metre = lQ9361 ysrda
1 rquare yard = 0.836 127 square metre.
&au* the 6rst of these requirea double diisiao, the toured double multiplication,
and the third a division. The most convenient and appropri8te conversion factor
forthiapurpo=ir
1 square metre - l-195 99 square y8rds,
given w&r the rcciproc& column of Table IV, which involves only one multiplication
opCr8tion.
nor further Uuatrativc acampk, reference ir invited to 45.2.
28
~ to .50 pCTCCntand
~ so on. Thus, on
@lY to be subject to
original values are
Ignificant figures in
circumstances
of
reflect the order of
( cfasrr, 5.1.1 )
GIVEN VALUE
‘~
T.
Xo.
Original
trted as such into
I an answer of 1 kg
v well say that the
be noted that the
(Ctually 50 percent
of 48”8 percent in
! value.
Ile given value as
we rules wou]d be
Kinal value is thus
(O
better
than
(e given vaiue and
(or to one ‘ Paifa’ ).
realize the given
T measurement,
if
oeness of rounding
put,
.
Tting monetary values
ffactor which involves
w one which involve~
Ilumns of both*Tables
Ild be used.
lither of the following
~uble multiplication,
JtCconversion factor
IIyonc multiplication
..
h
Rcwrittm
-
CALOWLATED
COSSVESSTED
VALVE
%QNITICAN’I
Rewritten
Value
i
4.5 in
25.4 mm/in
114.30
2
4.5010
4.4990
25.4 mm/in
114.32540
114.27460
3
1.20050
1.19950
25.4 mm/in
30.492700
304’67300
Ii * 0.01in
1.385
1.365
25.4 mm/in
35.1790
34.6710
1385
1365
I,?7 * 0.001 ill
l.~ltJ~
1.~]7~
25.4 mm/in
30.98292
30.93212
12198
12178
32.19107
3~.191 oq
30.48 cm/ft
981.1838136
981.1825944
.5
one
~ficance of the two
Iles to be followed
CONVERSION FAOTOSS
A—
r—
(;
7
17 miles 3 fttrlon~
8
3 I tons per sq in
31 tons pcr sq in
{ 31.00
9
12.2 to 12.8 oz/sq yr.1
{ lq.~
Io
537 US gallons
11
4 Imperial ~alirms
12
15 srrm 5 chhatalw
13
5 lolas 7 annas
14
13 acrrs
17.375 milrs
12.2 cs+q yd
537 L’S gal
4 Imp gal
1.60934 km/miles
27.96228
1057488 kg per sq
mm/tons per sq in
48,82128
33+X)6 g per sq m/oz
per sq yd
3.7853
1/US gal
4.5461 /Imp gal
5+4 tolas
13 acres
{ 13@0
’044
1
114mm
11432549
11427 4$B
0.001
114.325
114.275mm
120050
119950
30492.750
30467 8M
0.001
30.493
30,467 ‘m
0,01
35.18
34.67 ‘m
0.001
30.983
30.932 ‘m
0,0001
981.1832
kOW06 cm.
45
3219107
9219103
11480
351 7gfi
346 7xft
3098202
3093212
9811838 zfifl
9811 8259Kg
1
2 7962ZLI
0,001
27.962 km
2
3 I;i
48BZ .z~fi 4882 xzs
1
0.01
49 kg/sq mm
48.82 kg/sq mm }
3
4$1 x 101 to
4.3 X 101 g/sq m
122
128
141a ff5a
43a tiffz
10
2032.706
537
2032 Zoa
10
20.3 x 10s litrcs
2
18 Z$g
1826$
10
1
20 Iitres
18 litres }
1531
142 8fiB
6 34& ZZ6
142858
Sms
A OTE )
17375
,
63.45216
544
tii6 hrctare/acre
5,26092
13
1300
11%64 g/tola
ROUoNFDIMS
FTNAL
CONVSSBTED
VALUE
45010
44990
18.184
0.933104 kg/seer
Converted
Value
FINSSXEtSS
413,653
433.997
{ 4.0
15.31 seers
PAXZ OF
52f3tin2
526 O*
0.01
14.29 kg
0.1
63.5 g
0’.01
5 hectares
5.26 hectares
4
5
4
}
hksTE1 — In this example, the fineness of rounding off the’converted value, judging from its signiiicasst part according to RUIC V should be 0.0001 mm. But to ensure inter.
chamzeabili~ of machine Parts tic fuscnessof rounding n~ not be finer than 040 I mm accordingto Rule V.
5 miles, or say about 2.5 ft. Refcrencc is invited
NO;E 2 —-Here it will be noted that in the absence of information the precision of the given value has been assumed to be + O@OO
to discussion of this point under 4.3.1.1, example (b).
two separaterewritten V~UCShave been eonvencd to Msstmte how the di&esscc in precision influences the various steps in conversion. & stated
NOTE 3 — 1ssthescCXamPleS,
clsxwhcrc, the choice of precision for rewriting will depend upon the context in which the value is stated.
NOTE 4 — TM is anotherexampleillustratingthe needfor errercisb%the precaution diiuwd under S.1.2, that, when converting a single significant figure vahse, it is necessary
first to rewrite it to an appropriate degree of accuracy of statement.
16 annas is a rccognixcd fraction under The Standards of Weight Act 1939( Act IX of 1939 ).
NOTYS5 —ltola=
29
-.;ijl_
r
l8r 787.1956
A
( Clauses 3’; and 5.1 )
APPENDIX
“.)
TABLE IV DERIVED CONVERSION FACTORS AND COMMONLY USED UNITS
Conversion factors are given correct to five oc six significant figures de ending oa the mag&ude of the figure.
For cgmpletewt of convenidn ta glea refer to I3 : 786.1956.
More significant fig&cs.havc been specified in the cxc of’ cxac:
velure and those internationally accepted.
NON-MJBTISIO UN I T
Length
1 inch
1 foot
1 yard
f f$zng
254
3048
0.914 4
201*168
l-609 344
Area
1 square inch
1 square foot
1 aquarc yard
1 acre
*
:. .,
i
9,
I,
! .
L
I_ square mile
,,
,*
,.:
‘Cubic Measure and CIpdty
1 cubic inch
1 c u b i c foot
1 cubic
yard
”
1 Imperinl dalion ”
1 US gallon
>
:;
G-451 6
929.030 4
O-836 127 3G
4 046.86
40468 6
o-404 686
258.999
2*589 99
.I&387
1
042R 316 8
0*764 55
i
ton ( 2 240 lb avoirdupois )
pound (‘apothecary or’troy )
grain
tola
seer
maund
o-039 370 1
.O-032 808 4
l-093 61
o-004 970 97
O.GZl 37
in/mm
fi/cm
sq c@metrcs ( exact )
sq cenlimctres ( exact )
sq metrcs ( exact )
sq ntetrcs
acrts
hectares
he&es
sq kjlometrcs
0.155
O*OOl
l-195
O-000
O-024
2-471
O-003
O-386
sq in/sq cm
sq ft/sq CIll
sq yd/sq ,n
acrcjsq m
acre/are
acre/hectare
sq mile/hectarr
sq mil;/nq km
000
076 39
99
247 IO5
710 5
05
861 02
102
.
Wm
furlong/m
milr/km
cu seitimetres
cu netres
cu metrer
litrcs.
litrrs
O-061 024
35.314 71
l-307 95
01219 976
O-264 180
cu injcu cm
cu ft/cu m
cu ydlcu m
Imp gal/litre
US gal/l.itre
gra$
0.035-274 0
2.204 622
O-019 684 ‘1
0.984 21
2.679 23
15.432 4
O-085 735
l-071 69
O-026 792 3
04g
;:
Weight
1
1
1
1
1
1
,
millinielrcs C exact J
centimetrer ( exact j
metre+ ( exact )
mctws ( exact )
kilonti:rcs ( exact )
11663 8
o-933 10
37.324 2
kilqrams
kilqyanu
metric tons
kZgrams
grams
grams
k&&rams
kilbmms
Wkg
.
cwt/kg
ton/metric ton
lb ( ap or troy )/kg
grlg
tows
srlkg
md/kg
( Cotrtiffurd)
30
.
X3:787-MM
,.>
TABLE IV DERWf@ CONVEitSION FAOTORS AND COMMONLY USED UNITS — Conhf
!
METRICEqunALXti!C
:;
Norr-METE~o UIUT
Density mid
Concentration
WAper cu in/g pw cu cm
Ib per cu St/kg per cu m
ton per cu yd/metric ton per litrc
02 per gal ( Imp )/g per litre,
h per gal ( Imp ) ~g per Iitre
I
1
cubic inch
poun~ per cubic foot ,
ton per cu yard
-
1.72999
16.0185
003132898
I
I
ounce ( avoirdupois) per gallon ( Imp )
pound ( avoirdqmk ) per gallon ( ImP )
6.2362
99,779
grams per cu ccntimetrcs
kfiograms pcr C~mew
mewit-+on per htre
grams per litre
grams pcr litre
0.930’10
14.8816
4.96055
0.281849
grama.pcr ccntimctrc
grams per centimctrc
grants per ccntimetre
kilograms per kilometrc
1.07515
04367197
0+201 597
3.54800
02 per ft/g per cm
lb per ft/g per cm
lb per yd/g er cm
lb per mile/ ! g per km
70.307
4.88243
0.157488
33.9058
10.3322
grams per q ccntirnetrc
kdograots per sq metre
per sq ccntimewc
metric tort
grams per q metre
*
per sq millimetre
0.0142233
0.204816
6.3497
0.0294935
0.096784
lb per sq irs/gper sq cm
lb per sq ft/kg per sq m
ton pcr sq in/mew* ton pcr sq cm
oz per sq yd/g per sq m
irormal atmosphere/g per sq mm
Ukilartx
7.2330
ft-lb/kg metrc
Btu/kilocalorie
ft-lb/milliwatt hour
I
.
ibOSPSAOOAI.
ounce
*Linear
1
1
I
I
pm
,
0-57804
0.062428
75246
0,160354
011100221
Dcsmity
ounce per fout
pound per foot
pound per yard
pound per mile
4
?rcssurc, Strems and Area Dessaity
1
I
1
I
I
pound per square inch
pound per square foot
ton per square inch
ounce per square yard
tnormal atmosphere ( 14.6959 pound
per square inch )
Work, Energy and Heat
I foot-pound
1 British thermal unit
I fit-pound
0.138255
0.251996
0.3766
@illi~
‘\’
.,. >
Power
.
I
foot-pound per seeond
I
horse ~;wer
,,
( 550 foot-pound per second )
,,
0.138255
1.35582 ,,
76@40
$
0.74570
hours
3436832
2%55
.
$=
_
mctre per second
7.2330
0.73756
mcwe per second
0.0131509
1.34102
$&nVatts
ft-lb pcr see/kg mctrc per scc
ft-lb per see/watt
horse powcrfig m per scc
.
horse power/kilowatt
*Linear density units for iextilc yarns in both direct and indirect s stems ~ dealt with in IS: 234-1952 MrXhods for Determination of Mean Fibre Weight per Unit
(or Yam Mclidity in te.).
Melidity is a term recently introduced in textile industry
Length ( Cotton) and IS: 237-1951 Method for Determination of Cotton \arn ~rtt
standards to denote linear density of yarn or fitwein direet systemsof measurement. “Thc latestinternationallyrecommendedunit for meliditv. measurementis the tm, which IS
To inter-convert yam count and mclidity in tex, M
equal to one qram per kilomctre.
., the formula: Count x Mclidity = 590541, where count IS the number of hanks ( 840 yd )
o~ yarn per p6und.
,..’
~Thr Bureau International des Poids et Measures adopted the value Ofnormal atm~hcre
i.
$Thcse factors arc based on the standard value of acceleration due to gravity ~,~
lMcasures.
I
I
as 101325 newton per metret ( exact ).
I
cm per seca accepted internationally through the Bureau International
des Poida et
I
I
.
,,-
I
31.
I
i
,/’
is: 787- 19S6
A PPENDIX
4.
B
VALUES
GfVRN
%w&tct
42
VA
for
1“
um-~-
I
b
Jf&
amvwkm
No
I
No rewrtdng
No awwemion
a)
h)
I
Follow gencrafb
iMq&%imn
m
4s.a:
buc
5%!1 %HH:sk%
cantplace.
In ●bsenceof informadom,
assume*V3 unit●ccuracf
~
in
d
c)
I
camcxtor blfOnna- ●)
tlaq dor irtdii
●vulable,rewrite,ao as to
From
fa9t 8igni6cant
rewrite
Vek
place
@ccOrd-
ingly.
In case of vuhw
fractimw
convert m decimal
and
to (a)
round ofl’ ●ccomiing
aud (b) above,
re!aining
al -*Y
placel
8s nSq
to Umply about
*OY3
unit. m!CUrscy in last pkz
~~’$%%
I
of meaSu
eqtz avaii&
*b$le far determining
Sivcu
valtlc8, qkcia:I stmdmd
mr1i C&.
I.’use
OLafum stated
in tcrtzwof* minimum
d
. lowerlimit m ● nt.~i.
mumu periiutit,folkw
m
‘nf y instructions
~ under*3.2.
b) In caseof values,tatrd
I
both in main
in error ltAtcnualt Ue Same, rewrk
sivm
value in terms of
; limiting
vafum
to the
, same number ofdccimal
P%rnber
of decimal
places in msinvaluc
and
● -e ditlcrmr smtemrmt
erenb
that
rwvrite
[he
Iimiig
Values
m the
.;
mnverdom
dimmsimu.
Rewrite
main value so
*ame number
of P&cm
as iolemnc$
limit,
by
adding sigmlkant
zcrm
●nd by
wbeve necessq
wimblr roundmc
ofTdr..im alimd version of VUl-
,/
,,.
& hcrion.
, i%+rspmm
t.alue m terms
in~ val*.
\-
32
.---. ---.,----
-em.
.
.
~-
---
.
dividual twcd for
determining the
liencss;~dthe
mg.
abxnce of guidialg information,
follow
instructions m unfier
4.3.!.
4.4.3
I
B.wdrr-limr ‘the
lki~iw
Decinmh!ethcgi”=
value and round off
urcarry to 2 decimal
places in terms of
~lp:ae; ( or to 0,,?
I
Ddmalizethe~iver,
value and convert it
in respect of the
auociawd
unit of
measurtmcnx
ii
Ilcccmnry.
rcLaittitlg adcquatv oum.
k’
0(
d.cmml
places, 10 i’ns!llr
th. drgree 01 accurscy
which
may
he rrquircd in the
~u:;k~IUc.
‘rh;$
will
rfrpclld 0,, the app<,>priate fi”cncss 01
rounding
which is
m bc clmmn
in
relal iou to the use
to which the conVmrted V2111Cis 10
br Jlltt.
I
# Add
and thirdplaceOfdecimalinU= ufmillimetrc
‘.
II
a) Examine the in-
L
~?j!?j!j%::
inch
.k%w&n&d
(fi&fk~
Desi~”.ms
No rewriting
No cortvmximt
%dy
individually
for
decision
to cuwert
or not to convert,
then
decide how to rewrite.
!!S20wam?kmd
...
4.4.2
malpfatwa
Vdw and
(me m
to tderasm
limit wlua Ofmd&
..
++d
withphu and minusIi.
mittt If numberof deci-
2&x%#&Y%$%$:
Stqmdo *,1, in acmwacv
may
be assigned to all
vuf~r hction
dimmdatu
m Cngkerhg
th+inm.)
~
4.4.1
I
Iitab
Norcwming
v&,
the Riven
of limit-
.
.
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OF
INDIAN
STANDARDS
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Manak Bhavan, 9 Bahadur Shah Zafar Marg, NEW DELHI 110002
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1 621 17
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