Technical Support
 
EFFECT OF ALTITUDE AND TEMPERATURE
 

Altitude and temperature have a direct effect on the molecular structure of air. An adjustment in CFM (l/sec) must be made to accommodate such changes and to provide for efficient drilling.

At high altitudes there are less molecules in a given volume of air than at lower altitudes. Therefore, when the compressor displaces a given volume at a higher altitude, the air will be less dense. When less dense air is supplied to a down hole hammer a lower operating pressure will result.

  • For example: Operating a down hole hammer at 15,000 feet of elevation (4,572 m), at a temperature of 50° F (10° C), a down hole hammer would require almost 75% more volume than at sea level to operate at the same pressure.

High ambient temperature has much the same effect on air. At high ambient temperatures the air becomes less dense and at low ambient temperatures the air becomes more dense. These changes also require an adjustment to the air supply.

  • For example: Operating a down hole hammer at sea level with the ambient temperature at 100° F (38° C) versus 0° F (-18° C) would require almost 20% more volume to operate at the same pressure.

The following table may be used as a reference to calculate the air volumes necessary to maintain a given operating pressure at different altitudes and at different ambient temperatures.


CFM CORRECTION FACTORS
FOR AMBIENT TEMPERATURE AND ALTITUDE

[You may have to scroll right on your browser to view the entire chart]
 
ALTITUDE  
Feet 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000 11,000 12,000 13,000 14,000 15,000
Metres 0 305 610 914 1,219 1,524 1,829 2,134 2,438 2,743 3,048 3,353 3,658 3,962 4,267 4,572
 
Temperature  
°F °C  
-40 -40 0.805 0.835 0.866 0.898 0.932 0.968 1.004 1.043 1.084 1.127 1.170 1.217 1.266 1.317 1.371 1.426
-30 -34 0.824 0.855 0.886 0.920 0.954 0.991 1.028 1.068 1.110 1.154 1.198 1.246 1.297 1.349 1.403 1.460
-20 -29 0.844 0.875 0.907 0.941 0.976 1.014 1.052 1.092 1.136 1.180 1.226 1.275 1.327 1.380 1.436 1.494
-10 -23 0.863 0.895 0.928 0.962 0.999 1.037 1.076 1.117 1.161 1.207 1.254 1.304 1.357 1.411 1.469 1.528
0 -18 0.882 0.915 0.948 0.984 1.021 1.060 1.100 1.142 1.187 1.234 1.282 1.333 1.387 1.443 1.501 1.562
10 -12 0.901 0.935 0.969 1.005 1.043 1.083 1.123 1.167 1.213 1.261 1.310 1.362 1.417 1.474 1.534 1.596
20 -7 0.920 0.954 0.990 1.026 1.065 1.106 1.147 1.192 1.239 1.288 1.338 1.391 1.447 1.506 1.566 1.630
30 -1 0.939 0.974 1.010 1.048 1.087 1.129 1.171 1.217 1.265 1.315 1.365 1.420 1.478 1.537 1.599 1.664
40 4 0.959 0.994 1.031 1.069 1.110 1.152 1.195 1.241 1.290 1.341 1.393 1.449 1.508 1.568 1.632 1.698
50 10 0.978 1.014 1.051 1.091 1.132 1.175 1.219 1.299 1.316 1.368 1.421 1.478 1.538 1.600 1.664 1.732
60 16 0.997 1.034 1.072 1.112 1.154 1.198 1.243 1.291 1.342 1.395 1.449 1.507 1.568 1.631 1.697 1.766
70 21 1.016 1.054 1.093 1.133 1.176 1.221 1.267 1.316 1.368 1.422 1.477 1.536 1.598 1.662 1.730 1.800
80 27 1.035 1.074 1.113 1.155 1.198 1.244 1.291 1.341 1.394 1.449 1.505 1.565 1.628 1.694 1.762 1.834
90 32 1.055 1.094 1.134 1.176 1.221 1.267 1.315 1.365 1.419 1.475 1.533 1.594 1.658 1.725 1.795 1.868
100 38 1.074 1.114 1.154 1.198 1.243 1.290 1.339 1.390 1.445 1.502 1.560 1.623 1.689 1.756 1.828 1.902
110 43 1.093 1.133 1.175 1.219 1.265 1.313 1.363 1.415 1.471 1.529 1.588 1.652 1.719 1.783 1.860 1.936
120 49 1.112 1.153 1.196 1.240 1.287 1.336 1.386 1.440 1.497 1.556 1.616 1.681 1.749 1.819 1.893 1.970
 
 
Instructions: 1. Determine ambient conditions of air temperature (°F or °C) and altitude. (Feet or Metres)
    2. Find corrections factor from this table.
    3. Multiply the correction factor by the SCFM needed to obtain ACFM under conditions given.

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