What pressure limit applies when nitrogen is used to raise the pressure inside a low-pressure appliance for leak testing?
Correct Answer
C) No higher than ten psig
A low-pressure machine is not built like a high-pressure system. Its shell is designed for pressures near atmospheric and it is protected by a rupture disc that lets go at a low setting. Pressurizing it the way a technician would pressurize a split system would burst the disc and dump the entire charge outdoors. When nitrogen is used to bring a low-pressure machine above atmospheric pressure so leaks can be found, the pressure is raised slowly with a regulator and kept to a low ceiling well under the relief device setting.
Why This Is the Correct Answer
Ten psig is the accepted ceiling for pressurizing a low-pressure appliance during leak testing. It is high enough to push refrigerant or bubbles out through a leak so the leak can be found, and it stays safely below the rupture disc setting on these machines. Nitrogen must be fed through a regulator, never straight off the cylinder.
Why the Other Options Are Wrong
Option A: No higher than one hundred fifty psig
That is a pressure typical of nitrogen leak testing on a high-pressure system. Applying it to a low-pressure chiller would rupture the relief disc and release the entire refrigerant charge, and could damage the shell itself.
Option B: No higher than forty-five psig
Forty-five psig is still far above what the shell and relief device on a low-pressure machine are built to take. It would burst the rupture disc well before the technician finished setting up.
Option D: No higher than two hundred psig
Two hundred psig belongs to high-pressure and very high-pressure equipment. On a low-pressure chiller it is a dangerous pressure that would violently release the relief device.
Memory Technique
Ten for the low ten: low-pressure machines get ten psig, not the hundred fifty you would use on a split system.
Reference Hint
Low-pressure appliances are pressurized to no more than 10 psig for leak testing, using regulated nitrogen and staying below the rupture disc setting.
More epa-608-type-3 Questions
Some jobs on a chiller count as a major repair under the refrigerant rules, which changes what a technician is allowed to do with a badly leaking machine. Which job falls into that category?
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The motor of a hermetic centrifugal chiller sits inside the pressure boundary rather than outside it on a shaft. What follows from that construction?
An oxygen monitor is used to decide whether a chiller machine room is safe to enter after a refrigerant release. Below what oxygen reading is the atmosphere treated as oxygen deficient?
A low-pressure chiller's rupture disc has a discharge line running from it. Where does that line have to terminate?
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Which piece of equipment requires a technician to hold Type III certification before it may be serviced?
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During normal operation, what condition exists inside the evaporator of a running low-pressure centrifugal chiller?
In what unit is the required final recovery vacuum for a low-pressure appliance normally expressed?
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