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chendos
20-07-2007, 06:14 AM
hi,everyone
i am sizing the relief valve on the oil seperator of the low-tempreture stage.there have two rule per ASHRAE Standard 15 Mechanical Refrigeration Safety Code:

1.HIGH-STAGE OR SINGLE-STAGE COMPRESSORS: Flow is to be calculated based on 50°F (10°C) saturated suction temperature at the compressor suction.
2.LOW-STAGE OR BOOSTER COMPRESSOR: For those compressors that are capable of running only when discharging to the suction of a high-stage compressor, flow is to be calculated based on the saturated suction temperature equal to the design operating intermediate temperature.

follow 1 rule,the valve size is such large that i can't believe the result.but,l think the 2 rule is not fit in cascade system.
how to size? i need your help.
thanks