Back to Basics
Avoid Problems with
Units of Measurement
Faruk Civan
The Univ. of Oklahoma
Engineers need to clearly understand units,
and be able to convert, express, document,
and communicate them in correspondence,
operating instructions, and publications.
O
n Dec. 11, 1998, the National Aeronautics and Space
Administration (NASA) launched the first interplanetary weather satellite, the Mars Climate Orbiter
(MCO), to study the climate, atmosphere, and surface of
Mars and to serve as a communications relay for the Mars
Polar Lander (MPL), which was due to arrive a year later.
On Sept. 23, 1999, the spacecraft entered the planet’s atmosphere — 49 seconds earlier than expected, on a trajectory
approximately 170 km lower than planned — and NASA
lost radio contact with it. The $125-million orbiter was lost
and presumed to have disintegrated (1, 2).
The root cause of this incident? Inconsistent units
— specifically, failure to use metric units in the coding
of a software file used in trajectory models (1, 2). The
software application code SM_FORCES was written for
thruster performance data in English units. The output from
SM_FORCES was sent to a file called Angular Momentum
Desaturation (AMD). Existing software-interface documentation specified that the data in the AMD file were to be in
metric units, and the trajectory modelers assumed that they
were.
During the journey from Earth to Mars, propulsion
maneuvers were periodically performed to remove angular
momentum buildup in the onboard flywheels. Because the
angular momentum data were in English units, rather than
metric units, small errors were introduced in the trajectory
estimate over the course of the nine-month trip. Those small
errors added up to a 170-km mistake.
Fortunately, unit inconsistencies and incorrect converCopyright © 2013 American Institute of Chemical Engineers (AIChE)
sions rarely cause incidents of this magnitude. Nevertheless,
they can lead to errors and inefficiencies in process design
and operation. Prudent measures must be taken to avoid
problems in communicating units. Potsch (3) draws attention to the fact that, unfortunately, the International System
of Units (SI; see sidebar, p. 44) is still not being practiced
universally in spite of its well-recognized advantages.
Unit conversion is inevitable due to the diversity of
units used in engineering work. Data, equations, and other
information in scientific and engineering literature are not
all reported in consistent units. For instance, much of the
foundational chemical engineering research was typically
conducted and published using English units, whereas
many journals today require work to be reported in SI units.
Although most existing plants in the U.S. were designed
using English units and contain equipment sized in feet, gallons, pounds, etc., to compete globally, equipment manufacturers must supply products in both English and metric
sizes.
Units that are presented in design calculations, process
information, or other communications should be clearly
documented. In addition, operating procedures should be in
units that are familiar to the employees who run the plant.
This article details several examples of unit conversions
with explanations of common errors and how to avoid them.
It also provides advice on proper unit conversion procedures. Examples demonstrating how common and seemingly
logical approaches to unit conversion can lead to erroneous
results are presented.
CEP
February 2013
www.aiche.org/cep
43
Back to Basics
Unit conversion tool pitfalls
Most engineering software allows for internal conversion of the input and output data values in the prescribed
units of preference for the convenience of the user. Nevertheless, Rijgersberg, et al. (4) emphasize that “in the field
of unit conversion, many tools exist, often available online.
However, these tools are not based on a shared semantics
— the underlying knowledge is not formal and open, available from any location for any user. Moreover, current unit
converters typically do not include the notion of quantity, as
a result of which suitable alternative units for a given quantity are not given. At most, units are grouped under headers
that represent quantities, groups of quantities, or application
areas in the user interface, which the user can use to search
the suitable alternative units him/herself. Also, unit consistency checkers do exist, but they do not distinguish between
unit consistency and dimensional consistency. They mostly
cover only a limited number of units.”
Although dimensional analysis is straightforward, many
of the mathematical software tools used by engineers do
An SI Refresher
T
he International System of Units (abbreviated SI, from the
French Système International d’Unités) is built upon seven
base units for seven base quantities (dimensions) that are
mutually independent (Table 1).
Other quantities, called derived quantities, are defined in
terms of the seven base quantities through a system of equations. The units for these derived quantities (derived units) are
obtained from these equations and the seven SI base units.
Examples of SI derived units include square meter (m2) for
area, cubic meter (m3) for volume, meter per second (m/s)
for speed or velocity, meter per second-squared (m/s2) for
acceleration, kilogram per cubic meter (kg/m3) for mass
density, cubic meter per kilogram (m3/kg) for specific volume,
and so on.
For convenience, 22 derived units have been given
distinct names; Table 2 lists a few of them. Some of those,
in turn, are included in the names and symbols of other SI
derived units (Table 3).
Source: (8).
Table 1. The SI system is built upon seven base units.
Base Quantity
not satisfactorily perform automatic unit and dimensional
consistency checking (5). In fact, Rijgersberg, et al. (4)
draw attention to the existence of various pitfalls, peculiarities, and intricacies associated with the concepts and
implementation of the customary units of measure and
therefore attempt to alleviate them in the frequently used
Excel software, for example, by means of an add-in. Hangal
and Lam (6) provide a tool for automatic detection of unit
inconsistencies and errors in Java programs, but they also
emphasize that programming languages are not adequately
equipped with a means of checking unit consistency.
Aronson and Broman (7) point out that errors can occur in
physical unit checking that may not be readily apparent,
and note that attempts are being made to develop objectoriented equation-based modeling languages (such as Modelica, which is implemented in Mathematica). Furthermore,
software-aided automatic unit checking and conversion are
usually not convenient for day-to-day engineering tasks
and may not be readily available to the average practicing
engineer.
Table 2. Some SI derived units have been given special
names and symbols …
Name
Symbol
In Terms of
Other
SI Units
Force
newton
N
—
m-kg/s2
Pressure
pascal
Pa
N/m2
kg/m-s2
Energy,
Quantity
of Heat
joule
J
N-m
kg-m2/s2
Power
watt
W
J/s
kg-m2/s3
Electrical
Potential
Difference
volt
V
W/A
kg-m2/A-s3
Plane Angle
radian
rad
—
m/m = 1
Frequency
hertz
Hz
—
1/s
Quantity
In Terms of
SI Base
Units
Table 3. … and incorporated into other SI derived units.
Name
Symbol
Name
Symbol
meter
m
Dynamic Viscosity
pascal-second
Pa-s
Mass
kilogram
kg
Moment of Force
newton-meter
N-m
Time
second
s
Surface Tension
newton per meter
N/m
kelvin
K
Heat Capacity, Entropy
joule per kelvin
J/K
Specific Heat Capacity
joule per kilogram-kelvin
J/kg-K
watt per meter-kelvin
W/m-K
henry per meter
H/m
Length
Thermodynamic Temperature
Amount of a Substance
Derived Quantity
mole
mol
Electric Current
ampere
A
Thermal Conductivity
Luminous Intensity
candela
cd
Permeability
44
www.aiche.org/cep
February 2013
CEP
Copyright © 2013 American Institute of Chemical Engineers (AIChE)
Even though most engineering simulation tools do not
perform unit checking, they can handle unit conversion
once the user selects a unit system of preference from the
menu of prescribed unit systems. The user can specify a unit
system of preference, input the data in those units, and then
obtain results in various other unit systems. However, most
software has been designed to operate in a specific system
of units selected during the software development. Thus, if
the user-supplied input data are dimensionally or physically
inconsistent, or if data are entered but the correct units are not
specified, even the best software will give incorrect results.
Engineers must be prudent, comfortable, and proficient
at working and communicating in a variety of unit systems,
as well as converting among them (9). Despite units and unit
conversion being taught early and often, many students and
practicing engineers continue to make mistakes. The NASA
incident is just one drastic example of how costly a unit
conversion mistake can be.
the units of pressure (p), volume (V), number of moles (n),
molecular mass of the gas (M), speed (v), and temperature
(T) are used to derive the units of the absolute temperature.
However, the SI system expresses the absolute temperature in Kelvin (K), simply because it is customary to do so.
Therefore, we need to use a unit-correction factor in
Eq. 4 expressing that 1 K is equivalent to 8,314.51 J/kmol.
This factor is commonly known as the universal gas constant, R = 8,314.51 J/K-kmol (9).
On the other hand, some group or compound names
given to derived units have originated from units that are not
necessarily consistent. For example, the darcy, a hybrid or
mixed unit of a porous material’s permeability equivalent to
cP-cm2/atm-s, was obtained from Darcy’s law of flow of fluids through porous media (Eq. 5), where k is the permeability
of the porous media (darcy), μ is the fluid’s viscosity (centipoise), u is the volumetric fluid flux (cm/s), L is the length of
the porous media (cm), and p is the fluid’s pressure (atm).
Derived units
Length, mass, and time are fundamental physical
quantities that are independent of each other and define the
characteristic dimensions of physical systems. Their units of
measurement, which are the prescribed scales for assigning
numerical values to physical quantities according to a standard system of units, serve as the basis for deriving the units
of other quantities. Derived units are determined by means
of their defining physical equations. For example, Newton’s
second law of motion (F = ma) defines force (F) as the product of mass (m) and acceleration (a), and by extension the
units of force as the units of mass times the units of acceleration. In the SI system, this is represented by Eq. 1.
For convenience, some units are referred to by distinct
names, such as the newton (N) for force.
The units of force in the foot-pound-second (FPS) system are defined by Eq. 2.
The FPS system of units attempts to avoid confusion
between pound-mass and pound-force with the subscripts
m and f. The British gravitational system uses the slug as
the unit of mass, with 1 lbf = (1 slug)(1 ft/s2), so 1 slug =
32.1739 lbm. Such confusion does not exist in the SI system,
where mass has units of kilogram (kg) and force has units of
kg-m/s2.
However, not all of the derived units of the SI system
have been obtained this way. Ironically, even the carefully
designed SI system of units is not flawless. For example,
temperature (a derived dimension) should have been
expressed by one of the units in Eq. 3 based on the Georgian
energy temperature scale (10).
These consistent units can be inferred, for example,
from the thermal and kinetic equations of state for an ideal
gas with R = 1 (dimensionless), as shown in Eq. 4, where
Direct and functional unit-conversion factors
Unit systems expressed in absolute units, such as the
centimeter-gram-second (CGS) and meter-kilogram-­second
(MKS) systems, are referred to as consistent units. Therefore, unit conversion is not an issue when using such units.
For example, in SI units, the newton (N) is consistent with
the MKS system because it is expressed in the absolute units
kg-m/s2. Any system of mixed units is referred to as inconsistent units. Although it is widely practiced, the English
system of units is inconsistent.
A unit-conversion factor is the ratio of a quantity
expressed in one unit to its corresponding value in another
unit. In view of the diversity of units and availability of
numerous types and systems of units, it is neither possible
nor practical for an engineer to be familiar with all conversion factors. Fortunately, this is not necessary, as the conversion factors can be obtained readily from the conversion
Copyright © 2013 American Institute of Chemical Engineers (AIChE)
F = kg ×
m kg-m
= 2 =N
s2
s
F = lbm ×
T =
pV =
k=
(1)
ft ft-lbm
=
= lbf
s2
s2
( 2)
Pa-m 3 N-m
J
kg-m 2
=
=
=
kmol kmol kmol kmol-s 2
(3)
1
nMv 2 = nRT
3
(4)
µuL
∆p
(5)
CEP
February 2013
www.aiche.org/cep
45
Back to Basics
tables in numerous handbooks and Internet resources (8).
For example, the equivalences of the darcy, i.e., the
unit-conversion factors associated with permeability, can be
expressed in various ways, as shown in Eq. 6.
Frequently, unit conversion operations require the application of an equation. For example, the relationship between
the absolute temperatures expressed in the units of Kelvin
(K) and Rankin (R) is given by Eq. 7.
In many cases, conversion factors are simple constant
values or factors, as demonstrated by the previous examples.
These are called direct unit-transformation factors. Most
unit-conversion operations require multiplication of a series
of conversion factors.
However, some unit conversions require suitable functional definitions, such as T(°C) + 273.15 = T(K) or
T(°F) + 459.67 = T(R) for temperature-unit conversions.
Similarly, the conversion between absolute and gage pressures is given by p(psia) = p(psig) + 14.7 (the value of
14.7 psia used here is an approximate value assumed for the
local atmospheric pressure, which actually varies by location). These are called functional unit transformations, which
are referred to as the affine transformations.
Some functional unit transformations may be more complicated. For example, a functional unit-conversion factor is
required to convert between the actual gas volume (e.g., in
ft3) and the gas volume expressed at a reference or standard
condition (e.g., in scf or standard ft3). The unit conversion
factor required depends on the gas conditions. The reference pressure and temperature conditions are ps = 1 atm =
14.696 psia and Ts = 60°F = 519.67 R (where the subscript
s indicates standard conditions). The real gas equation of
state is Eq. 8, where p is the absolute pressure, V denotes
the actual volume, Z is the real gas deviation factor (a
function of pressure and temperature), n is the number of
moles, R is the universal gas constant, and T is the absolute
temperature. Applying Eq. 8, the conversion factor can be
cP-cm 2
P-cm 2
g-cm
= 0.01
= 0.01
atm-s
atm-s
atm-s 2
= 9.8692 × 10 −9 cm 2 = 9.8692 × 10 −13 m 2
[ k ] = darcy =
(6)
T ( R ) = 1.8 × T ( K )
( 7)
pV = ZnRT
(8)
Vs scf
T
p
519.67 p
p
= s
=
= 35.36
V ft 3
ps ZT
14.696 ZT
ZT
D = 4 2τ
46
k
φ
www.aiche.org/cep
(9)
(10 )
February 2013
CEP
calculated as shown in Eq. 9.
A major source of error is the casual use of such
conversion factors. The conversion factors must have
their associated units labeled so as to cancel each other in
the unit-conversion calculation. For example, the conversion factor between a fraction and a percentage may be
confusing unless it is expressed with proper labels as
1.0 fraction/100%.
Be aware that some units may have several variations.
For example, the density conversion factor is 1 ton/ft3 =
321.07 lbm/gal in the imperial FPS unit system used in
the U.K., but 1 ton/ft3 = 267.36 lbm/gal in the U.S. FPS
unit system. This is because 1 gal in imperial units equals
1.20095 gal in U.S. units. Therefore, to avoid errors in communicating units between different parties, be specific in
what you are referring to. If you are referring to the imperial
unit, write gal(imperial) or gal(U.K.), and write gal(U.S.) for
the U.S. units.
Unit conversion in equations
To convert an equation that has prescribed units, regardless of whether its variables are consistent or inconsistent
with the absolute units, so that it can be used with certain
other units, first substitute the desired units and then multiply
each variable by unit conversion factors to convert them to
the prescribed units of the equation. Next, combine the various conversion factors into lumped factors, and then round
them off to the proper number of significant digits.
Example 1: Mean hydraulic diameter. The mean hydraulic diameter D (m) of capillary flow paths in porous materials can be estimated by Eq. 10 using consistent SI (m-kg-s)
units (11, 12), where τ is the tortuosity (dimensionless),
k is the permeability (m2), and f is the porosity of the porous
media (fraction). The objective is to convert this equation so
that it can be used with the following units: mean hydraulic
diameter in μm2, permeability in millidarcy, and porosity as
a percentage.
Insert the proper unit-conversion factors required for
dimensional consistency into Eq. 10 to obtain Eq. 11. Combine all the conversion factors to get Eq. 12.
Now, check the converted equation by solving it with
variables in the desired units, and compare the resulting
numerical value with the value obtained from the original
equation using the following numerical data: τ = √2, f =
0.20 = 20%, and k = 100 millidarcy = 9.8692 × 10–14 m2.
Substituting these values into Eq. 10 results in D = 4.7 ×
10–6 m, or 4.7 μm, which is the value calculated by Eq. 12.
Undergraduate and graduate students, as well as industrial practitioners, often incorrectly start with the original
units considered in Eq. 10 and convert them to the desired
units as shown in Eq. 13. This is a common mistake, and
results in Eq. 14, which is incorrect.
Copyright © 2013 American Institute of Chemical Engineers (AIChE)
Example 2: Emptying liquid from a bottle. Some unitconversion calculations are very cumbersome and intricate,
and therefore prone to algebraic errors unless carefully
executed. This is the case for Eq. 15, which describes the
emptying of a liquid from a bottle (13), where V is the bottle
volume (cm3), C is the Whalley’s flooding constant (dimensionless), D denotes the internal diameter of the bottle neck
(cm), g is the gravitational acceleration (981 cm/s2), ρL
and ρG are the density of the liquid and gas phases (g/cm3),
respectively, and t is the emptying time (s). The objective is
to convert this equation so that it can be used with the
(D
m)
(12 )
( k darcy )
(13)
(14 )
1
1
4 ρL 4 + ρG4
V gallon
10 3 millidarcy
1 darcy
1 darcy
9.8692 × 10 −13 m 2
100 percent
φ fraction
1 fraction
k
φ
πC 2 D 2 gD ( ρL − ρG )
(
(11)
k
φ
1 m
= 4 2τ
10 –6 m
D = ( 3.18 ) 4 2 τ
V=
1 darcy
9.8692 × 10 −13 m 2
10 3 millidarcy
1 darcy
1 fraction
φ percent
100 percent
( k millidarcy )
10 −6 m
= 4 2τ
1 m
D = ( 0.314 ) 4 2 τ
(D m)
following units: V in gal, D in in., g = 32.1739 ft/s2, ρL and
ρG in lbm/ft3, and t in min.
Do this by inserting the proper unit-conversion factors
into Eq. 15 to obtain Eq. 16.
Combine all the conversion factors to get Eq. 17. Test
the result using the following numerical data: C = 0.9,
D = 2.54 cm = 1.0 in, g = 981 cm/s2 = 32.1739 ft/s2,
ρL = 1.0 g/cm3 = 62.4 lbm/ft3, ρG = 1.2 × 10–3 g/cm3 =
7.5 × 10–2 lbm/ft3, and t = 300 s = 5 min. Substituting these
values into Eq. 15 gives V = 4.36 × 104 cm3, which equals
11.5 gal, the value calculated by Eq. 17.
)
1
2
t
(15 )
2
−
3.785 × 10 m
1 gallon
2
10 cm
1m
πC 2
3
2.54 cm
1 in.
D in.
=
4
ρ
1
4
+ρ
1
4
lb m
ft 3
2
1
{a × b} 2
60 s
1 min
t min
453.6 g
1 lb m
1 ft
30.48 cm
(ρL − ρG )
lb m

ft 3
3
1
4
(16 )
2
where
a= g
V = 0.9
ft
s2
30.48 cm
1 ft
πC 2 D 2 gD ( ρL − ρG )
(
1
4 ρL + ρ
4
2.54 cm
1 in.
( D in.)
1
4
G
)
1
2
b=
453.6 g
1 lb m
1 ft
30.48 cm
3
t
(17 )
2
Copyright © 2013 American Institute of Chemical Engineers (AIChE)
CEP
February 2013
www.aiche.org/cep
47
Back to Basics
Example 3: Henry’s constant. This example applies a
functional unit-transformation factor to a formula in one set
of units to convert it to a different set of units. The correlation of Henry’s constant data for ethylbenzene is expressed
in Eq. 18, where the Henry’s constant and temperature are
given in the units of MPa and K, respectively (14).
To use Eq. 18 with units of psia and °F and a base-10
logarithm instead of a natural logarithm, a conversion is
required, as shown in Eq. 19.
Upon rearrangement, Eq. 19 becomes Eq. 20.
To test the accuracy of this conversion, consider the
value of H = 248 MPa calculated for T = 350 K by Eq. 18.
In the desired units, H = 36 psia and T = 170°F. Substituting
T = 170°F into Eq. 20 yields H = 36 psia, confirming the
accuracy of the conversion.
Example 4: Heat content of gases. The application of
functionally variable unit-conversion factors is illustrated
by Eq. 21. This equation, from Watson and White (15),
estimates the heat content of gases flowing through pipes by
ln H = 0.7062 +
3.866 × 10 3 6.932 × 10 5
−
T − 80
(T − 80 )2
(18 )
6.89475 MPa

psia
(19 )
2.303 × log ( H psia )
= 0.7062 +
log H = −0.53188 +
H = H o + C γRT
Btu
H
scf
Vs scf
V ft 3
acoustic measurement. In the equation, H is the heat content
of the gas (J/m3), Ho is an empirical constant (J/m3), C is an
empirical constant (J-kmol/m3-kg), γ is the ratio of specific
heat capacities defined at constant pressure and volume
conditions (= Cp/Cv, dimensionless), R is the universal gas
constant (= 8,314.47 J/kmol-K), T is the absolute temperature (K), and t is the transit time (s) of sound measured over
the transducer spacing of L (m) between a source and a
transducer. The desired units are H in Btu/scf, Ho in Btu/ft3,
C in Btu-mol/ft3-g, R = 10.7316 psia-ft3/lb-mol-R, T in R,
t in μs, and L in cm. By substituting the proper conversion
factors, Eq. 21 can be converted to Eq. 22.
Substituting Eq. 9 into Eq. 22 yields Eq. 23. Without
volume conversion, this equation simplifies to Eq. 24.
Typical data for ethane are Ho = 143 Btu/ft3, C = 54.2
Btu-mol/ft3-g, γ = 1.19, t = 2,000 μs, and L = 62 cm (15).
Using Eq. 24, the heat content is calculated to be H = 1,750
Btu/ft3, and Eq. 23 yields H = 178 Btu/scf when the flowing
gas is at 150 psia and 80°F (540 R). Then, check the results
3.866 × 10 3
1K
− 80
1.8 R
T °F + 459.67 R
6.932 × 10 5
–
1K
− 80
1.8 R
T °F + 459.67 R
2
3.0216 × 10 3 9.7524 × 10 5
−
T + 315.67 (T + 315.67 )2
t
L
( 20 )
2
( 21)
1,055.06 J
1 Btu
1 ft
0.3048 m
3
Btu
= Ho 3
ft
1,055.06 J
1 Btu
1 ft
0.3048 m
3
+ {a × b × c}
( 22 )
where
a= C
Btu-mol
ft -g
c = (T R )
48
3
1K
1.8 R
g
mol
kg
kmol
(t
s)
( L cm )
www.aiche.org/cep
1,055.06 J
1 ft
1 Btu
0.3048 m
1s
3
b=γ R
psia-ft
3
lbmol-R
8,314.47
10.7316
J
kmol-K
3
psia-ft
N-m
J
kg-m
2
s
N
lbmol-R
2
6
10 s
1m
100 cm
February 2013
CEP
Copyright © 2013 American Institute of Chemical Engineers (AIChE)
H
ZT
Btu
t
=
H o + 4.3 × 10 −6 C γRT
scf
35.36 p
L
H
Btu
t
= H o + 4.3 × 10 −6 C γRT
ft 3
L
2
2
( 23)
( 24 )
of the unit conversion by converting the units of one value
to the units of the other using Eq. 9: 178 Btu/scf × (35.36 ×
150/540) (scf/ft3) = 1,750 Btu/ft3.
Final remarks
The NASA incident is one example of the severe consequences that can result from unit conversion error and
miscommunication (2). Obsolete units are often used in old
designs, plants, and literature, and engineers have to deal
with unfamiliar units when working in facilities that use
nonstandard unit systems. Therefore, engineers must understand the importance of converting units in calculations,
documenting units in plant information, and using clear and
concise units in operating instructions and publications.
To achieve unit conversion in an equation, substitute the
variables in the desired units and then convert them to the
equation’s original units with the required conversion factors. Apply the conversion factors together with their associated identity labels to ensure that the identity labels also
cancel with each other during the unit conversion process. A
common mistake is to do exactly the reverse; that is, to start
with the original units considered in an equation and then
attempt to convert them to the desired units.
Check converted equations by solving them in both the
original and converted units and then comparing the result-
ing numerical values. Ensure that the result matches the
value obtained from the original equation when converted
back into the original units.
Numerical results obtained from a calculator or computer after unit conversion may exceed the number of
significant digits based on the accuracy of the numerical
values. Round the numerical results obtained after unit conversion to the proper number of significant digits in order
to limit the accuracy to that of the least-accurate variable or
conversion factor.
CEP
Literature Cited
1.
2.
3.
4.
5.
6.
7.
8.
FarUk Civan is the Martin G. Miller Chair Professor in the Mewbourne
School of Petroleum and Geological Engineering at the Univ. of Oklahoma (100 East Boyd, SEC Room 1210, Norman, OK 73019; Phone: (405)
325-6778; Fax: (405) 325-7477; Email: fcivan@ou.edu). He formerly held
the Brian and Sandra O’Brien Presidential and Alumni Chair Professorships. Previously, he worked at the Technical Univ. of Istanbul, Turkey.
His principal research interests include fossil and sustainable energy
resources development; carbon sequestration; unconventional gas and
condensate reservoirs; reservoir and well/pipeline hydraulics and flow
assurance; oil and gas processing, transportation, and storage; multiphase transport phenomena in porous media; environmental pollution
assessment, prevention, and control; and mathematical modeling and
simulation. He is the author of two books: Porous Media Transport Phenomena (John Wiley & Sons, 2011), and Reservoir Formation Damage:
Fundamentals, Modeling, Assessment, and Mitigation (Elsevier, 2007).
He has published more than 310 technical journal articles; edited books,
handbooks, encyclopedias, and conference proceedings; and presented
worldwide more than 125 invited seminars and/or lectures at various
technical meetings, companies, and universities. He holds an advanced
degree in engineering from the Technical Univ. of Istanbul, Turkey, an MS
from the Univ. of Texas at Austin, and a PhD from the Univ. of Oklahoma,
all in chemical engineering. He is a member of AIChE and the Society
of Petroleum Engineers (SPE), and a member of the editorial boards of
several journals. He has served on numerous AIChE and SPE technical
committees. Civan has received 20 honors and awards, including five
distinguished lectureship awards and the 2003 SPE Distinguished
Achievement Award for Petroleum Engineering Faculty.
Copyright © 2013 American Institute of Chemical Engineers (AIChE)
9.
10.
11.
12.
13.
14.
15.
Lloyd, R., “Metric Mishap Caused Loss of NASA Orbiter,”
www.cnn.com/TECH/space/9909/30/mars.metric.02
(Sept. 1999).
National Aeronautics and Space Administration, “Lost in
Translation,” System Failure Case Studies, 3 (5), nsc.nasa.gov/
SFCS/SystemFailureCaseStudyFile/Download/5 (Aug. 2009).
Potsch, K., “The State of the Units or the Units of the States,”
Journal of Petroleum Technology, 59 (7), pp. 16–18 (July 2007).
Rijgersberg, H., et al., “How Semantics Can Improve Engineering Processes: A Case of Units of Measure and Quantities,”
Advanced Engineering Informatics, 25 (2), pp. 276–287
(Jan. 2011).
DeCarvalho, R., “Units and Dimensions Suite for Matlab,”
MATLAB Release MATLAB 7.1.0 (R14SP3), www.mathworks.
com/matlabcentral/fileexchange/10070-units-and-dimensionssuite-for-matlab (Feb. 2006).
Hangal, S., and M. S. Lam, “Automatic Dimension Inference
and Checking for Object-Oriented Programs,” Proceedings
of ICSE: International Conference on Software Engineering,
pp. 155–165 (2009).
Aronsson, P., and D. Broman, “Extendable Physical Unit
Checking with Understandable Error Reporting,” Proceedings of
the 7th Modelica Conference, Como, Italy (Sept. 20–22, 2009).
Gaboury, J. A. M., “Units of Measurement, Introduction to
the International System of Units [SI] Le Système International
d’Unites,” Montreal (Quebec), Canada (1990).
Wiggins, D. G., “Unit Conversion: Dimensional Analysis,”
Visionlearning, SCI-2 (2), www.visionlearning.com/library/
module_viewer.php?mid=144 (2008).
Levenspiel, O., “Hot Lips, a Cold Heart, and Thermomometry,”
Chemical Engineering Education, 9 (3), pp. 102–105, 137
(1975).
Carman, P. C., “Flow of Gases through Porous Media,” Butterworths, London (1956).
Civan, F., “Effective Correlation of Apparent Gas Permeability in
Tight Porous Media,” Transport in Porous Media, 82 (2),
pp. 375–384 (2010).
Whalley, P. B., “Two-Phase Flow during Filling and Emptying of
Bottles,” International Journal of Multiphase Flow, 17 (1),
pp. 145–152 (Jan.–Feb. 1991).
Civan, F., “Use Exponential Functions to Correlate Temperature
Dependence,” Chem. Eng. Progress, 104 (7), pp. 46–52
(July 2008).
Watson, J. M., and F. A. White, “Acoustic Measurement for
Gas Btu Content,” Oil and Gas Journal, 80 (14), pp. 217–225
(Apr. 5, 1982).
CEP
February 2013
www.aiche.org/cep
49