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According to ASHRAE guidelines 1996,what should you do if the pressure in a system rises from 1 mm to a level above 2.5 mm Hg a standing vacuum test,
the system should be checked for leaks
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with a low-pressure chiller, what must you do after recovering the liquid refrigerant
recover the vapor refrigerant
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EPA reg. require that commercial & industrial process refrigerant be repaired when the leak rate exceeds _____% annually
35%
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where would you place a leak detector probe to check for leaks into the water box with the water removed
the leak detector probe should be first placed in the drain vave to check for leaks
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how do you determine when enough vapor has entered the refrigeration system before you charge refrigerant liquid
when the system temp rises to 36* ,to prevent boiling of the liquid refrigerant ,that could freeze water in the system
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when removing oil from a low pressure system, the temp should be 130* because,
this will boil off the refrigerant out of the oil
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hydrostatic test tube or eddy current test is used for what
x-ray device used to check for cracks and leaks in the metal tubes
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R-11 & R-123 low pressure refrigerants removal starts with what
liquid removal, than switches to vapor removal.
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charged low-pressure refrigerant system may be most efficiently leak checked if you do what to the system
- you can raise the pressure of the refrigerant, taking it out of a vacuum,by covering the chiller with a heated blanket, or circulating hot water.
- remember low-pressure means it's in a vacuum, therefore the refrigerant won't leak out, the outside air will be sucked in.
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why do chillers using R-11 & R-123 require purge units
these are special purge units that will purge non-condensibles. the system works in a vacuum.
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a typical setting for high-pressure cut-out control on a recovery unit used for evacuating the refrigerant from a low-pressure chiller is ;
10 psig
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appliances containing more than 50Lbs of refrigerant except for commercial or industrial, be repaired when the leak rate exceeds______of the charge per year
15%
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after servicing, why is refrigerant vapor re-introduced to the refrigeration system before refrigerant liquid?
liquid charged into a deep vacuum will boil and may lower temp. enough to freeze water in the tubes
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R-11 at a pressure of 18.1 inches of mercury vacuum has a saturation temp of
32*
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recovery after 1993, evacuation low-pressure system to the following level
25 millimeter of hg absolute
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under EPA regulations, which of the following methods can be used for a no-major repair
warming the refrigerant
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which of the following repairs would be considered major repair
replacement of the condenser, evaporator,compressor, or heat reclaim coil
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systems do not need to be evacuated all the way to the prescribed level only when
leaks in the system make evacuation to the prescribed level unattainable
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after reaching the required recovery vacuum on a system, you should do what
wait a few minutes to see if the pressure rises, indicating refrigerant in the oil
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when recovering before 1993, you must evacuate to
25 inches of hg before making any repairs
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the primary purpose of a purge unit on a chiller is to;
remove non-condensibles from the system
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under what code group of ASHRAE standard 34 does R-123 fall
B-1
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on a centrifugal system the purge unit takes its suction from where
the top of the condensor
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refrigeration is added to the centrifugal system through what
evaporator charging valve
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