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Air CompressorAir Discharge Volume : Technical Data

Normal | Pressure drop in direct piping | Ventilation volume | Drain volume

Various calculations

Drain volume

Drain volume when compressing air

The moisture which is taken in with air for compression becomes water droplets by the compression and is discharged as drain. The drain volume generated changes subject to the temperature and humidity of the intake air and the discharge pressure.

The drain volume which is expected to be generated per 1m3 wet air under the intake condition if the standard atmosphere pressure is compressed to 7kgf/cm2.G is calculated as follows.

Saturated moisture volume table (relative humidity 100%)
  Temperature ºC by 1ºC unit
0 1 2 3 4 5 6 7 8 9
Temperature
ºC by 10ºC unit		 90 420.1 433.6 448.5 464.3 480.8 496.6 514.3 532.0 550.3 569.7
80 290.8 301.7 313.3 325.3 337.2 349.9 362.5 375.9 389.7 404.9
70 197.0 204.9 213.4 222.1 231.1 240.2 249.6 259.4 269.7 280.0
60 129.8 135.6 141.5 147.6 153.9 160.5 167.3 174.2 181.6 189.0
50 82.9 86.9 90.9 95.2 99.6 104.2 108.9 114.0 119.1 124.4
40 51.0 53.6 56.4 59.2 62.2 65.3 68.5 71.8 75.3 78.9
30 30.3 32.0 33.8 35.6 37.5 39.5 41.6 43.8 46.1 48.5
20 17.3 18.3 19.4 20.6 21.8 23.0 24.3 25.7 27.2 28.7
10 9.40 10.0 10.6 11.3 12.1 12.8 13.6 14.5 15.4 16.3
0 4.85 5.19 5.56 5.95 6.35 6.80 7.26 7.75 8.27 8.82
-0 4.85 4.52 4.22 3.93 3.66 3.40 3.16 2.94 2.73 2.54
-10 2.25 2.18 2.02 1.87 1.73 1.60 1.48 1.36 1.26 1.16
-20 1.067 0.982 0.903 0.829 0.761 0.698 0.640 0.586 0.536 0.490
-30 0.448 0.409 0.373 0.340 0.309 0.281 0.255 0.232 0.210 0.190
-40 0.172 0.156 0.141 0.127 0.114 0.103 0.093 0.083 0.075 0.067
-50 0.060 0.054 0.049 0.043 0.038 0.034 0.030 0.027 0.024 0.021
-60 0.019 0.017 0.015 0.013 0.011 0.0099 0.0087 0.0076 0.0067 0.0058
-70 0.0051                  

 

Calculation
V : Drain volume  [/h]
GS1 : Saturated moisture volume
(By inlet air temperature)		 [g/m3]
GS2 : Saturated moisture volume
(By outlet dew point)		 [g/m3]
P : Air pressure [kg/cm2]
A : Air flow [Nm3/min]
Example
Inlet temperature : 45 [ºC]
Pressure : 6 [kg / cm2]
Flow rate : 20.8 [Nm3 / min]
Outlet dew point : 12 [ºC]
V = (65.3–10.6) × 1.033

P + 1.033		 × 20.8
× 60 × 1

10		 = 10.03 [/h]
Formula to calculate the drain
ω = γs × (χ'–100) × 1

100

γs : Saturated moisture volume under the discharge temperature

Example
Saturated moisture volume under 40ºC
γs = 51.0 [g/m3]
χ' = 357.44 [%]
ω = 51.0 × (357.44–100) × 1

100
  = 131.29 [g/m3]

In case of ZU11

131.29

1.033 + 7		 × 1.4 × 60 = 1372.88 [cc/h]
    approximate 1.37 [/h]

In case of ZU22

131.29

1.033 + 7		 × 3.5 × 60 = 3432.20 [cc/h]
    approximate 3432 [/h]