SECTION 7
Approximate Capacity Correction for Altitude
Altitude
(ft.)
Sea Level
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
11000
12000
14000
15000
QR-25 Series
52201-107, December 2012
25 PSIG
40 PSIG
1.00
1.00
0.996
0.993
0.992
0.987
0.987
0.981
0.982
0.974
0.977
0.967
0.972
0.961
0.967
0.953
0.962
0.945
0.957
0.938
0.951
0.931
0.945
0.923
0.938
0.914
0.927
0.897
0.918
0.887
Notes:
1.) Correction factors are approximate and shown for single stage
compressors.
2.) For two stage compressors use the interstage pressure to find the
correction factor.
3.) This chart does not allow for air tools which require more free air at
altitudes above sea level.
4.) To find the capacity of a compressor at a given altitude, multiply the
rated capacity of the compressor by the factor corresponding to the
altitude and discharge pressure. The result will be the actual capacity
(CFM) of the compressor at the given altitude.
REFERENCE INFORmATION
Correction Factors
60 PSIG
80 PSIG
1.00
1.00
0.992
0.992
0.984
0.977
0.974
0.967
0.963
0.953
0.953
0.940
0.945
0.928
0.936
0.915
0.925
0.900
0.915
0.887
0.902
0.872
0.891
0.858
0.878
0.839
0.852
0.805
0.836
0.784
36
3501 Wismann Lane, Quincy IL - 62305-3116
90 PSIG 100 PSIG 125 PSIG
1.00
1.00
0.998
0.987
0.972
0.969
0.959
0.954
0.944
0.940
0.931
0.925
0.917
0.908
0.902
0.890
0.886
0.873
0.868
0.857
0.853
0.840
0.837
0.818
Quincy Compressor
1.00
0.982
0.962
0.942
0.923