General Information
Measures of Pressures
1
lb. per square inch = 144 lb.
per square foot = 0.068
atmosphere = 2.042 inches of
mercury @ 62˚F (17˚C) = 2.31
feet of water at 62˚F (17˚C).
1
atmosphere = 30 inches of
mercury at 62˚F (17˚C) = 14.7
lbs. per square inch = 2116.3 lb.
per square foot = 33.95 feet of
water at 62˚F (17˚C).
1
foot of water at 62˚F (17˚C)
= 62.355 lbs. per square foot =
0.433
lb. per square inch.
1
inch of mercury at 62˚F (17˚C)
= 1.132 feet of water = 13.58
inches of water = 0.491 lb. per
square inch.
Column of water 12 inches high,
1
inch diameter = .341 lb.
Useful Conversion Charts
Fractions Decimals Millimeters
33
⁄64
.515625
13.097
17
⁄32
.53125
13.494
35
⁄64
.546875 13.891
9
⁄16
.5625
14.288
37
⁄64
.578125
14.684
19
⁄32
.59375
15.081
39
⁄64
.609375
15.478
5
⁄8
.625
15.875
41
⁄64
.640625 16.272
21
⁄32
.65625
16.669
43
⁄64
.671875
17.066
11
⁄16
.6875
17.463
45
⁄64
.703125
17.859
23
⁄32
.71875
18.256
47
⁄64
.734375
18.653
3
⁄4
.750
19.050
49
⁄64
.765625
19.447
25
⁄32
.78125
19.844
51
⁄64
.796875
20.241
13
⁄16
.8125
20.638
53
⁄64
.828125
21.034
27
⁄32
.84375
21.431
55
⁄64
.859375
21.828
7
⁄8
.875
22.225
57
⁄64
.890625 22.622
29
⁄32
.90625
23.019
59
⁄64
.921875
23.416
15
⁄16
.9375
23.813
61
⁄64
.953125
24.209
31
⁄32
.96875
24.606
63
⁄64
.984375
25.003
1
1.000
25.400
Decimal and Millimeter Equivalents of Fractions (Inches)
Fractions Decimals Millimeters
1
⁄64
.015625
.397
1
⁄32
.03125
.794
3
⁄64
.046875 1.191
1
⁄16
.0625
1.588
5
⁄64
.078125
1.984
3
⁄32
.09375
2.381
7
⁄64
.109375
2.778
1
⁄8
.125
3.175
9
⁄64
.140625
3.572
5
⁄32
.15625
3.969
11
⁄64
.171875
4.366
3
⁄16
.1875
4.763
13
⁄64
.203125
5.159
7
⁄32
.21875
5.556
15
⁄64
.234375
5.953
1
⁄4
.250
6.350
17
⁄64
.265625 6.747
9
⁄32
.28125
7.144
19
⁄64
.296875 7.541
5
⁄16
.3125
7.938
21
⁄64
.328125
8.334
11
⁄32
.34375
8.731
23
⁄64
.359375
9.128
3
⁄8
.375
9.525
25
⁄64
.390625 9.922
13
⁄32
.40625
10.319
27
⁄64
.421875
10.716
7
⁄16
.4375
11.113
29
⁄64
.453125
11.509
15
⁄32
.46875
11.906
31
⁄64
.484375
12.303
1
⁄2
.500
12.700
Pressure Conversions
(
feet of water to inches of mercury)
Feet of
Water
Inches of
Mercury
 1
0.9
 2
1.8
 4
3.5
 6
5.3
 8
7.1
10
8.8
12
10.6
14
12.4
16
14.1
18
15.9
20
17.7
22
19.4
24
21.2
26
23.0
28
24.8
30
26.5
32
28.3
34
30.0
Pressure Conversion (feet of water to pounds per square inch)
Based on formula (psi) = Pressure Head [ft. of water] x 0.433
Pressure Head
(
Ft. of Water)
Pressure
(
psi)
Pressure Head
(
Ft. of Water)
Pressure
(
psi)
Pressure Head
(
Ft. of Water)
Pressure
(
psi)
0
0
200
 87
410
177
5
2.2
210
 91
420
182
10
4.3
220
 95
430
186
20
8.7
230
100
440
190
30
13
240
104
450
195
40
17
250
108
460
199
50
22
260
113
470
203
60
26
270
117
480
208
70
30
280
121
490
212
80
35
290
126
500
216
90
39
300
130
550
238
100
43
310
134
600
260
110
48
320
139
650
281
120
52
330
143
700
303
130
56
340
147
750
325
140
61
350
151
800
346
150
65
360
156
850
368
160
69
370
160
900
390
170
74
380
164
950
411
180
78
390
169
1000
433
190
82
400
173
337
Appendix
C
Air & Multipurpose
General Purpose
Heavy Duty
Push-on
Chemical Transfer
Cleaning Equipment
Food
Transfer
Washdown
Marine
Material Handling
Abrasives
Bulk Transfer
Cement & Concrete
Mining
Petroleum
Aircraft Fueling
Dispensing
Dock
Transfer
Spray
Steam
Vacuum
LPG Delivery
Water
Discharge
Suction & Discharge
Washdown
Welding
Coupling Systems
Equipment
Appendix