Shellab SVAC4-2 - Manual (Page 31)

31
REFERENCE 3
APPENDIX
The Effect of Altitude (Atmospheric Pressure) on Maximum Attainable
Vacuum Level
The Maximum Possible Vacuum Attained is based on your Altitude. Basically, the higher you are the less vacuum
you can attain. Because free air is less dense at higher altitudes (i.e. lower atmospheric pressure) operation at these
higher altitudes has the effect of reducing the capacity and maximum vacuum levels attainable. In general flow is not
affected, just the maximum vacuum level attainable.
It is also important to consider the relationship between atmospheric pressure and altitude as it affects vacuum pump
performance.
Refer to the following table to correct for vacuum pump performance at various altitudes.
Vacuum Gauge Reading When Read at Altitude
Altitude Above
Sea Level (Feet)
Altitude Above
Sea Level
(Meters)
Atmospheric
Pressure (psi)
Maximum Vacuum
Level
Attainable (inches
Hg)
Vacuum Level
Loss at
Altitude
Maximum Vacuum
Level
Possible at this
Altitude
0’ 0 M 14.70 psi 29.921” Hg - -
1000’ 305 M 14.16 psi 28.9” Hg 3.4% 96.6%
2000’ 610 M 13.66 psi 27.8” Hg 7.1% 92.9%
3000’ 914 M 13.16 psi 26.8” Hg 10.4% 89.6%
4000’ 1219 M 12.68 psi 25.8” Hg 13.8% 86.2%
5000’ 1524 M 12.22 psi 24.9” Hg 16.8% 83.2%
6000’ 1829 M 11.77 psi 24.0” Hg 19.8% 80.2%
7000’ 2134 M 11.33 psi 23.1” Hg 22.8% 77.2%
8000’ 2438 M 10.91 psi 22.2” Hg 25.9% 74.1%
9000’ 2743 M 10.50 psi 21.4” Hg 28.6% 71.4%
10,000’ 3048 M 10.10 psi 20.6” Hg 31.3% 68.7%
11,000’ 3353 M 9.71 psi 19.8” Hg 33.9% 66.1%
12,000’ 3658 M 9.34 psi 19.0” Hg 36.5% 63.5%
13,000’ 3962 M 8.97 psi 18.3” Hg 39.0% 61.0%
14,000’ 4267 M 8.62 psi 17.5” Hg 41.4% 58.6%
15,000’ 4752 M 8.28 psi 16.9” Hg 43.6% 56.4%