On low pressure chillers, moisture typically enters the refrigerant system through ans ✓✓ air leaks from areas with gaskets or fittings
The maximum test pressure for leak testing a low pressure centrifugal is: ans ✓✓
10 psig
Leak test and repair the chiller to reduce refrigerant loss from a pruge unit on CFC-
11 chiller ans ✓✓ ...
A hydrostatic tube test kit is used to: ans ✓✓ determine if a tube leaks
Commercial and industrial process refrigeration systems must be repaired when the
leak rate exceeds ____ of the charge per year. ans ✓✓ 35%
Refrigerant recovery typically start with liquid recovery it is faster. ans ✓✓ ...
A rupture disc on a recovery vessel for a low pressure refrigerants relieves at: ans
✓✓ 15 psig
According to ASHRAE Guideline 3-1996, if the pressure in a system rises from 1 mm Hg to a level above ____ during a standing vacuum test, the system should be checked for leaks. ans ✓✓ 2.5 mm Hg
The primary water source for a recovery unit condensing coil is _____. ans ✓✓ local municipal water supply When recharging a refrigeration system with R-11, what vaporpressure is necessary in the shells before changing with liquid? ans ✓✓ 16.9" Hg vacuum
After recovering the liquid refrigerant you must: ans ✓✓ recover the vapor refrigerant
According to the EPA there is approximately _____ refrigerant vapor left in an average 350 ton R-11 chiller at 0 psig pressure once all the R-11 liquid has been removed. ans ✓✓ 100 pounds
Charging refrigerant liquid into a refrigeration system when it is under a 29 inch Hg vacuum can cause the: ans ✓✓ system water to freeze
A system does not have to be evacuated all the way to the required level when: ans ✓✓ leaks in the appliance make evacuation to the prescribed level unattainable
Which of the foloowing repairs would ALWAYS be considered "major" under EPA's ans ✓✓ replacement of evaporator coil
Under EPA's regulation's _______ is used to pressurize a low pressure chiller for the purpose of opening the system for a non major repair? ans ✓✓ warming the
refrigerant
If you are using a recovery machine manufactored AFTER 11-15-93 you must evacuate an low pressure appliance to _______ before making a major repair. ans
✓✓ 25 mm of Hg absolute After reaching the required recovery vacuum on a chiller, you should ans ✓✓ Wait for at least a few minutes to see if the system pressure rises, indicating that there is till refrigerant in a liquid form or in the oil
The pressure corresponding to 32 F for R-123 ans ✓✓ 20 inches of HG vacuum
When evacuating a system the use of too large a vacuum pump can cause? ans ✓✓ trapped water to freeze
Refrigerant-11 at a pressure of 17 inches HG vacuum has a saturation temperature of: ans ✓✓ 35F
During the evacuation of a system containing large amounts of moisture you can prevent freezing of this moisture by increasing the pressure with______gas ans ✓✓ nitrogen
ASHRAE standard 15-1994 requires that each machinery room must activate an alarm and mechanical ventilation beofre refrigerant concentrations exceed: ans ✓✓ the threshold limit valve and time weighted average
The typical design burst pressure for a rupture disk on a low pressure centrifugal air-conditioning system is set at_______ ans ✓✓ 15 psi
Heat pumps that have been retrofitted from R22 to R407C should be leak checked with: ans ✓✓ pressurized nitrogen
When a new system has been assembled, the first thing to do is: ans ✓✓ pressurize the system with inert gas and leak check