Austin
3901 Woodbury Drive
P.O. Box 41869
Austin, Texas 78704
Tel: 512.444.1835
Fax: 512.444.5522
www.mechreps.com
CONVERSION FACTORS
FORMULAS & CONVERSIONS
To Convert
Feet of Water
Feet of Water
Gallons of Water
Gallons of # 2 Oil
Horsepower
Horsepower
Horsepower (boiler)
Horsepower (boiler)
Inches of Mercury
Inches of Mercury
Kilowatts
Kilowatts
Pounds of Water
Pounds of Water
Pounds/ Sq.Inch
Therms of Gas
Tons (refrigeration)
Watts
To
Inches of Mercury
Pounds/ Sq. Inch
Pounds of Water
BTU’s
Kilowatts
BTU / Hr.
BTU / Hr.
Kilowatts
Feet of Water
Pounds/ Sq. Inch
BTU/ Hr.
Watts
Cubic Feet
Gallons
Feet of Water
BTU’s
BTU/ Hr.
BTU/ Hr.
Multiply By
0.8826
0.4335
8.3452
140,000
0.7457
2545
33479
9.803
1.133
0.4912
3413
1000
0.01602
0.1198
2.307
100,000
12,000
3.413
Electrical Formulas
„•Ǥ‡”‘—”‘ˆ‘‘Ž‹‰ǣ
‘”—’•ǣ
‘”ƒ•ƒ†Ž‘™‡”•ǣ
Armstrong
To Find
Single Phase
Two Phase-Four
Wire
Amps when
“HP” is
known
HP x 746
V x %EFF x PF
HP x 746
V x %EFF x PF x 2
HP x 746
V x %EFF x PF x 1.73
Amps when
“KW”is
known
KW x 1000
V x PF
KW x 1000
V x PF x 2
KW x 1000
V x PF x 1.73
Amps when
“kVA”is
known
kVA x 1000
V
kVA x 1000
Vx2
kVA x 1000
V x 1.73
Kilowatts
Kilovolt-Am
ps “kVA”
HP
V x A x PF
1000
V x A x PF x 2
1000
V x A x PF x 1.73
1000
VxA
1000
VxAx2
1000
V x A x 1.73
1000
V x A x %EFF x PF
746
V=VOLTS
Three Phase
A=AMPS
V x A x %EFF x PF x 2
746
EFF=EFFICIENCY
V x A x %EFF x PF x 1.73
746
PF=POWER FACTOR
San Antonio
4710 Perrin Creek #300
San Antonio, Texas 78217
Tel: 210.650.9005
Toll Free: 800.650.6507
Fax: 210.590.1645
www.mechreps.com
Rio Grande Valley
1409 N. Stuart Place Road
Suite E
Harlingen, Texas 78552
Tel: 956.412.1110
Fax: 956.412.1350
www.mechreps.com
MOTOR FULL-LOAD AMPERES
Three-Phase AC
Squirrel-Cage &
HorseWound-Rotor
Single Phase AC
power 208 V 230 V 460 V 115 V 200 V 230 V
1/6
4.4
2.5
2.2
1/4
5.8
3.3
2.9
1/2
2.3
2
1
9.8
5.6
4.9
3/4
3.2
2.8
1.4 13.8 7.9
6.9
1
4.1
3.6
1.8
16
9.2
8
1.5
5.7
5.2
2.6
20 11.5 10
3.4
2
7.5
6.8
24 13.8 12
11
4.8
3
9.6
34 19.6 17
5
16.7 15.2 7.6
56 32.2 28
7.5
24
22
11
80
46
40
10
31
28
14
100 57.5 50
15
46
42
21
20
59
54
27
25
75
68
34
30
88
80
40
40
114 104 52
50
143 130 65
60
170 154 77
75
211 192 96
100
273 248 124
125
342 312 156
150
396 360 180
200
528 480 240
Basic Fan Laws
Variation
Fan Speed Change
Density Change
Volume
Varies Directly with Speed Ratio
No Change
Pressure
Varies with SQUARE of
Speed Ratio
Horse
Power
(
)
)ʹ
(
Varies with CUBE of Speed
Ratio
(
)͵
Varies DIRECTLY with
Density Ratio
(
)
Varies DIRECTLY with
Density Ratio
• BAC • Berner • Car-Mon • Cemline • ClimateMaster • Dri-Steem • Energy Labs •
Fulton • Greenheck • Lochinvar • Price • Pro Hydronic • VMC/Amber Booth • Yaskawa
(
)
FabricAir
55
50
DR
Y
Dry-Bulb Temperature
Dry-Bulb
Temperature
80
D
80
75
50
PE
–B
TU
Y
30
M
PE
R
Specific
Volume
60
ET
15
BU
LB
TE
DEWPOINT TEMPERATURE – ºF
-°
F
20
AT
UR
E
65
14.5
Dry-Bulb
Temperature
W
55
10
70
45
5
0
5
10
10
10
20
30
5
50
40
10
80
60
70
40
60
60
40
40
10
35
35
30
30
20
20
13.0
0
30
25
20
Y
IDIT
HUM
IVE
T
A
REL
13.5
40
30
15
90
45
50
35
65
45
50
60
40
110
50
14.0
80
120
100
55
20
90
50
130
50
70
40
25
LP
HA
70
Humidity
Ratio
160
140
ET
Dew Point
Temperature
55
150
15.0
Relative
Humidity
Enthalpy
170
30
UN
75
R
PO
Wet-Bulb
Temperature
180
AIR
DRY
OF
Specific
Volume
190
20
DRYBULB TEMPERATURE – °F
70
80
15
90
20
100
110
10
10
0
30
25
ENTHALPY – BTU PER POUND OF DRY AIR
This chart was constructed using data from the
“Thermodynamic Properties of Moist Air”
compiled by John A. Goff and S. Gratch and
Barometric Pressure 29.92 Inches of Mercury.
0
HUMIDITY RATIO – GRAINS OF MOISTURE PER POUND OF DRY AIR
80
90
45
Humidity
Ratio
AI
R
Dehumidification
Dew Point
Temperature
60
85
70
Heating
85
200
60
Cooling
Relative
Humidity
Enthalpy
40
Re
90
35
e 0
Lin t 1
n a
it o dity
ra i
Humidification
tu um
Sa e H
iv
lat
Humidity Ratio, Dew Point Temp.
or
Vapor Pressure
Wet-Bulb
Temperature
0%
60
F
ND O
POU
PER
FEET
BIC
- CU
UME
VOL
CIFIC
SPE
or
Vapor Pressure
PSYCHROMETRIC CHART