Why should the oil be removed from a low-pressure system at 130°f

Recovery/recycling equipment does not necessarily need to be capable ofhandling more than one refrigerant, according to EPA regulations.

72Low pressure appliances must be evacuated to the level of 25 mm Hg vac beforemaking major repairs using recovery/recycling equipment manufactured BEFORENovember 15, 1993.Low pressure appliances must be evacuated to the level of 25 mm Hg abs whenusing recovery/recycling equipment manufactured AFTER November 15, 1993.In accordance with EPA regulations, controlled hot water may be used topressurizethe systemforthepurpose ofopeningitfora non-majorrepair.You must recover the liquid refrigerant before recovering thevaporrefrigerantin a low pressurechiller R-11 or R-123 system refrigerant removalstarts with liquid removal.About 100 lbs. of refrigerant vapor is left in an average 350 ton R-11chiller at O psig pressure when all the R-11 liquid refrigerant has beenremoved .If the pressure in a system rises from 1 mm hg vac to a level above 2.5 mm hgvac during a standing vacuum test, then according to ASHRAE Guideline3-1990, the system should be checked for leaks.After reaching the required recovery vacuum on an appliance, wait foratleast a few minutes to see if the system pressure rises. This indicatesthatthere is still refrigerant in liquid form or in the oil.The temperature should be at 130 degrees F when removing oil from a lowpressure system so that less refrigerant will be contained in the oil than atalower temperature.A rupture disc on the evaporator of a low - pressure refrigeration systemrelieves at 15 psig.The system water pumps, recovery compressor, and recovery condenserwatershould all be turned on during vapor removal from a refrigeration system.A heater used with a recovery vessel aids in the quicker transfer of vapor tothe chiller.Local municipal water supplies are the primary water source for recoveryunitcondensing coils.Water must be circulated through a chiller during refrigerant evacuationin order to prevent freezing of the water.Replacement of an evaporator is always considered "MAJOR" under EPAregulations.5.Recharging Techniques16.9" Hg vac is necessary in the shells before recharging a refrigerationsystem with liquid R-11.After system servicing, refrigerant vapor is re-introduced to therefrigeration system before refrigerant liquid because liquid charged into adeep vacuum will boil and may lower temperatures enough to freeze water in thetubes. You can tell that enough vapor has entered the refrigeration systemand thatit’s safe to charge refrigerantliquidwhen the refrigerantsaturation temperaturereached 36degrees F.

736.RefrigerationChillers that use CFC-11 and HCFC-123 require purge units because thosesystems operate below atmosphericpressure.The primary purpose of a purge unit on a CFC-11 chiller is to remove non-condensables from thesystem.The purge unit ALSO removes air from the system and returns the recycledrefrigerant to the unit.

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