Compressed air dryer selection guide
To correctly select a dryer, you must consider the actual flow rate, pressure, temperature, ambient temperature and required pressure dew point temperature of the compressed gas. Dryer processing capacity Qs = Qa * C1 * C2, where Qa is the actual flow rate of the compressed gas.
Example:
The inlet air pressure of the cold dryer is 0.7Mpa, the inlet air temperature is 40℃, the ambient temperature is 40℃, the actual flow rate of compressed air Qa is 10m3/min, and the required pressure dew point is +2℃, then: The cold dryer processing capacity Qs = Qa * C1 * C2, refer to Table 1 and Table 2. C1 = 0.80, C2 = 1.22, Qs = 9.76, and the XS-10A specification should be selected as the most suitable.
| Inlet temperature (℃) | Inlet pressure (Mpa) | ||||||
| 01.4 | 0.5 | 0.6 | 0.7 | 0.8 | 0.9 | 1.0 | |
| 25 | 0.49 | 0.43 | 0.40 | 0.37 | 0.35 | 0.33 | 0.32 |
| 30 | 0.57 | 0.50 | 0.46 | 0.42 | 0.40 | 0.37 | 0.36 |
| 35 | 0.84 | 0.77 | 0.71 | 0.65 | 0.62 | 0.59 | 0.57 |
| 40 | 0.99 | 0.91 | 0.85 | 0.80 | 0.77 | 0.74 | 0.72 |
| 45 | 1.20 | 1.11 | 1.05 | 1.00 | 0.97 | 0.94 | 0.92 |
| 50 | 1.37 | 1.30 | 1.24 | 1.18 | 1.14 | 1.10 | 1.07 |
Pressure dew point and water content
The pressure dew point of the air outlet of the cold dryer is 2-10℃ at 0.7 Mpa, which is equivalent to the atmospheric pressure dew point of -23–16℃. At this time, the water content is about 0.82-1.48g/m3.
When the inlet temperature is 40℃, the air temperature at the outlet of the cold dryer is about 22-26℃, which is equivalent to the relative humidity of 4-7% at an atmospheric pressure of 20℃.
Pressure dew point – atmospheric dew point conversion chart
Atmospheric dew point-moisture content relationship table
| Dew point (℃) | Moisture content (g/m3) | Dew point (℃) | Moisture content (g/m3) | Dew point (℃) | Moisture content (g/m3) | Dew point (℃) | Moisture content (g/m3) |
| 20 | 17.30 | 0 | 4.847 | -20 | 1.074 | -40 | 0.1757 |
| 19 | 16.31 | -1 | 4.523 | -21 | 0.9884 | -41 | 01590 |
| 18 | 15.37 | -2 | 4.217 | -22 | 0.9093 | -42 | 0.1438 |
| 17 | 14.48 | -3 | 3.930 | -23 | 0.8359 | -43 | 0.1298 |
| 16 | 13.63 | -4 | 3.660 | -24 | 0.7678 | -44 | 0.1172 |
| 15 | 12.83 | -5 | 3.407 | -25 | 0.7074 | -45 | 0.1005 |
| 14 | 12.07 | -6 | 3.169 | -26 | 0.6463 | -46 | 0.09501 |
| 13 | 11.35 | -7 | 2.946 | -27 | 0.5922 | -47 | 0.05844 |
| 12 | 10.66 | -8 | 2.737 | -28 | 0.5422 | -48 | 0.07675 |
| 11 | 10.01 | -9 | 2.541 | -29 | 0.4960 | -49 | 0.06886 |
| 10 | 9.309 | -10 | 2.358 | -30 | 0.4534 | -50 | 0.06171 |
| 9 | 8.819 | -11 | 2.186 | -31 | 0.4141 | -51 | 0.054 |
| 8 | 8.270 | -12 | 2.206 | -32 | 0.3779 | -52 | 0.040 |
| 7 | 7.750 | -13 | 1.876 | -33 | 0.3445 | -53 | 0.029 |
| 6 | 7.260 | -14 | 1.736 | -34 | 0.3138 | -54 | 0.021 |
| 5 | 6.797 | -15 | 1.605 | -35 | 0.2856 | -55 | 0.014 |
| 4 | 6.360 | -16 | 1.483 | -36 | 0.2597 | -56 | 0.011 |
| 3 | 5.947 | -17 | 1.369 | -37 | 0.2359 | -57 | 0.008 |
| 2 | 5.559 | -18 | 1.261 | -38 | 0.2141 | -58 | 0.005 |
| 1 | 5.192 | -19 | 1.165 | -39 | 0.1940 | -59 | 0.003 |
