Tuesday, 3 January 2017

Atmospheric Pressure at Site Elevation

Atmospheric Pressure  at  Site Elevation
  Feet  
  Meters  
  psia  
Atm
Bar (a)
kPa kg/cm2
 In Hg 
 Mm Hg 
0
0
14.7
1.00 1.013 101 1.03
29.9
760
328 100 14.5 0.99 1.000 100 1.02 29.5 752
500
150
14.4
0.98 0.994 99.4 1.01
29.4
747
656 200 14.3 0.97 0.988 98.8 1.01 29.2 743
1000
300
14.2
0.96 0.976 97.6 1.00
28.9
734
1312 400 14.0 0.95 0.964 96.4 0.98 28.5 725
1500
450
13.9
0.94 0.956 95.6 0.98
28.3
719
2000 600 13.7 0.93 0.939 93.9 0.96 27.8 706
2500
750
13.4
0.91 0.923 92.3 0.94
27.3
694
3000
900
13.2
0.89 0.906 90.6 0.92
26.8
681
3500
1070
12.9
0.88 0.888 88.8 0.91
26.3
668
4000
1220
12.7
0.86 0.871 87.1 0.89
25.8
655
4500
1370
12.4
0.85 0.858 85.8 0.87
25.4
645
5000
1520
12.2
0.83 0.842 84.2 0.86
24.9
633
5500
1680
12.0
0.81 0.825 82.5 0.84
24.4
620
6000
1830
11.8
0.80 0.811 81.1 0.83
24.0
610
6500
1980
11.5
0.78 0.794 79.4 0.81
23.5
597
7000
2130
11.3
0.77 0.781 78.1 0.80
23.1
587
7500
2290
11.1
0.76 0.767 76.7 0.78
22.7
577
8000
2440
10.9
0.74 0.750 75.0 0.76
22.2
564
8500
2590
10.7
0.73 0.737 73.7 0.75
21.8
554
 
Impact of elevation on air separation plant capacity and power To provide a pre-determined amount of air to an air separation processes (as measured by weight or standard volumes such as SCF or Nm3 ) air compressors that will be operated at higher elevations must process greater physical volumes of air (actual cubic feet or actual cubic meters) than would be required if the plant were located near sea level. 
At higher elevations, more power is required to deliver the same amount of compressed air (actual weight or volume) to the air separation process.  This is  because the pressure ratio across the air compressor will be greater at higher elevations when the air feed is compressed to the design operating pressure as measured in absolute pressure units.      
This table can be used to determine the required inlet capacity for new air compression equipment.  It can also be used, with the aid of general compressor performance relationships or specific compressor performance curves, to estimate changes in performance for relocated air compression equipment.   

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