General Reference
Velocity pressures
VEL
FPM		 VP
in. water		 VEL
FPM		 VP
in. water		 VEL
FPM		 VP
in. water
500 .016 1800 .202 4400 1.21
600 .022 2000 .249 4600 1.32
700 .031 2200 .302 4800 1.44
800 .040 2400 .359 5000 1.56
900 .050 2600 .421 5200 1.69
1000 .062 2800 .489 5400 1.82
1100 .075 3000 .561 5600 1.96
1200 .090 3200 .638 5800 2.10
1300 .105 3400 .721 6000 2.24
1400 .122 3600 .808 6200 2.40
1500 .140 3800 .900 6400 2.55
1600 .160 4000 .998 6600 2.72
1700 .180 4200 1.10 6800 2.88
Conversion factors
QUANTITY STANDARD ENGLISH UNITS STANDARD METRIC UNITS OTHER UNITS
in. wg pascals psi
Pressure 1 248.36 .03602
.00403 1 .00015
27.761 6894.7 1
13.635 3386.4 .49116
.03937 9.7779 .00142
.53681 133.32 .01934
407.98 101325 14.696
VOLUME
FLOW		 cfm m3/s m3/min
1 .000472 .02832
2118.9 1 60.000
35.314 .01667 1
.58858 .00028 .01667
2.1189 .00100 .06000
.03531 .00002 .00100
VELOCITY ft./min. m/s m/min.
1 .00508 .30480
196.85 1 60.000
3.2808 .01667 1
.05468 .00028 .01667
88.000 .44704 26.822
101.34 .51479 30.887
Air density at different altitudes and temperatures
Altitude Atmospheric
Pressure		 Temperature in Degree Fahrenheit
-20 0 20 40 60 80 100
-1000 31.02 0.0936 0.0886 0.0858 0.0824 0.0792 0.0762 0.0735
0 29.92 0.0903 0.0854 0.0827 0.0794 0.0764 0.0735 0.0709
1000 28.86 0.0871 0.0824 0.0798 0.0766 0.0736 0.0709 0.0684
2000 27.82 0.0839 0.0794 0.0769 0.0738 0.0710 0.0684 0.0660
3000 26.81 0.0808 0.0765 0.0741 0.0712 0.0684 0.0659 0.0635
4000 25.84 0.0779 0.0738 0.0715 0.0686 0.0660 0.0635 0.0612
5000 24.89 0.0751 0.0710 0.0688 0.0661 0.0635 0.0611 0.0590
6000 23.98 0.0723 0.0684 0.0663 0.0636 0.0612 0.0589 0.0569
7000 23.09 0.0697 0.0659 0.0639 0.0613 0.0589 0.0565 0.0545
8000 22.22 0.0671 0.0634 0.0614 0.0590 0.0567 0.0541 0.0521
9000 21.38 0.0644 0.0610 0.0591 0.0568 0.0546 0.0525 0.0506
10000 20.58 0.0620 0.0587 0.0569 0.0525 0.0525 0.0495 0.0488

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