Users who know the high and low test chambers know that the standard high and low temperature test chamber uses two refrigerants, R23 and R404A respectively. Then, how to distinguish the scope of use of this kind of refrigerant? Here are some of them:
First, low pressure high temperature refrigerant
The condensing pressure Pk ≤ 2 ~ 3 kg / cm (absolute), the evaporation temperature T0 > 0 ° C. For example, R11 (Freon 11, CFCL3, monofluorotrichloromethane, T0 = 23.7 ° C), R21, R114, T0 = 23.7 °C. This type of refrigerant is suitable for use in centrifugal refrigeration compressors for air conditioning systems. Usually 30 ° C, Pk ≤ 3.06kg / cm.
Second, medium pressure medium temperature refrigerant
The condensing pressure Pk ≤ 20 kg/cm (absolute), 0 ° C > T0 > -60 ° C. Such as R717 (ammonia, NH3), R12, R22 (Freon 22, CHCLF2, difluorochloromethane), R502 (an azeotropic refrigerant, composed of R22 and R115 (pentafluoro-chloroethane, C2F5CL)), etc. Such refrigerants are generally used in conventional single-stage compression and two-stage compression piston refrigeration compressors.
Third, high pressure low temperature refrigerant
The condensing pressure Pk ≥ 20 kg / cm (absolute), T0 ≤ -70 ° C. Such as R23 (Freon 23, CHF3, trifluoromethane), R13 (CF3CL), R14 (CF4), carbon dioxide (CO2), R503, ethane, ethylene, etc., such refrigerants are suitable for the low temperature part of cascade refrigeration equipment Or in a cryogenic device below -70 °C.
According to the above-mentioned refrigerant application, the high temperature and low temperature test chamber of -70 ° C, the high and low temperature impact test chamber, the high temperature part of the liquid nitrogen cryogenic low temperature box use the medium temperature refrigerant (R404A), and the low temperature part uses the low temperature refrigerant (R23). The -20 °C high and low temperature test chamber uses only medium temperature refrigerant (R404A).
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