What is the correct way to pressurize a small sealed system for leak testing after the refrigerant has been recovered?
Correct Answer
D) Pressurize with dry nitrogen through a pressure regulator, staying below the system's test pressure limit
Dry nitrogen is inert, carries no moisture, and is delivered through a regulator so the technician controls the pressure applied to the system. Compressed air brings moisture into the system and can form an explosive mixture with refrigerant oil under pressure. Oxygen is far worse, since oxygen under pressure in contact with oil can ignite violently. Pressurizing with refrigerant and then releasing it is knowing venting, which is prohibited during service, maintenance, repair, and disposal.
Why This Is the Correct Answer
Nitrogen is dry and chemically inert, so it will not react with compressor oil and it will not leave moisture behind to form acid in the system. The regulator is the essential part of the answer: nitrogen cylinder pressure is far above anything the appliance can survive, so pressure must be controlled and kept under the system test limit.
Why the Other Options Are Wrong
Option A: Charge the system with shop compressed air and listen at the joints for escaping air on the line
Shop air carries moisture into a system that has to stay dry, and compressed air mixed with refrigerant oil under pressure has caused system explosions. It is a poor leak indicator on a small charge as well.
Option B: Add oxygen from a welding cylinder to raise the system pressure quickly from the torch outfit
Oxygen under pressure in contact with hydrocarbon oil can ignite, and the torch cart is exactly where that mistake starts. Using an oxygen cylinder to pressurize a refrigeration system is among the most dangerous errors a technician can make.
Option C: Pressurize the system with refrigerant vapor and release it to the atmosphere when the test is finished outdoors
Charging a system with refrigerant only to release it afterward is knowing venting, indoors or out. Refrigerant may serve as a trace gas mixed with nitrogen, but that mixture then has to be recovered.
Memory Technique
Nitrogen is dry, dead, and dull. That is exactly what you want inside a refrigeration system.
Reference Hint
Prohibition on knowing venting under Clean Air Act Section 608; nitrogen with a regulator is the accepted pressure test medium.
More epa-608-type-1 Questions
An under-counter ice maker is one factory-sealed cabinet, while a modular ice machine head is joined to a remote condenser by field-run tubing. What certification does servicing the modular machine's circuit require?
A technician recovers refrigerant from a small appliance using a recovery machine that was manufactured in 1991. What recovery level must that older equipment achieve?
Two technicians recover from identical refrigerators with working compressors, one using a 1991 recovery machine and the other a 2015 machine. Why do their required recovery levels differ?
System-dependent recovery equipment may be used only on appliances that normally hold up to what amount of refrigerant?
What feature defines a self-contained recovery unit and sets it apart from the system-dependent kind?
When system-dependent recovery equipment is used on a small appliance whose compressor still runs, how can that working compressor be put to use?
Recovery from a small appliance has slowed down and the pressure is barely moving. What accepted technique helps drive the remaining refrigerant out?
After the recovery unit stops pulling on a small appliance, how does a technician confirm that the recovery is actually complete?
A sealed small appliance offers no service port at all. What has to happen before recovery equipment can be connected to it?
As refrigerant from a string of small appliances collects in a recovery cylinder, what fill limit applies to that cylinder?
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