A packaged terminal unit charged with R-410A needs its charge recovered, and the only machine in the shop carries a label listing older refrigerants and a much lower working pressure. How should the technician proceed?
Correct Answer
C) A machine rated for that refrigerant is needed, because its pressures exceed the older design
Recovery equipment is built and certified for particular refrigerants, and the label states which ones. R-410A works at pressures far above the refrigerants the earlier generation of machines was designed and tested for, so an older machine's compressor, hoses, fittings and relief settings are simply not rated for it. Using one is a safety problem before it is a compliance problem. The charge in the appliance is small, but the pressures it develops are the same as they would be in a large system, and it is pressure rather than quantity that the machine has to withstand.
Why This Is the Correct Answer
Certification of recovery equipment is refrigerant specific, and the pressure rating that comes with it is a physical limit on the machine's compressor, vessel, hoses and relief devices. R-410A operates well above the design pressures of equipment built for the earlier refrigerants, so a machine whose label does not list it must not be put on that appliance regardless of how little refrigerant is inside.
Why the Other Options Are Wrong
Option A: The machine may be used if it is flushed first, since recovery is a purely mechanical process
Flushing addresses cross contamination between refrigerants. It does nothing about a pressure rating, which is a property of the machine's construction and cannot be changed in the field.
Option B: The machine may be used at reduced speed, since small appliances hold very little refrigerant
The hazard scales with pressure, not with quantity. A few ounces of R-410A produce the same saturation pressure as a truckload of it at the same temperature.
Option D: Any certified machine may be used, since certification covers every refrigerant on the market
Equipment certification names the refrigerants the machine was tested with. It is not a blanket approval, and newer high pressure refrigerants are the clearest case of that limit.
Memory Technique
Ounces do not set the pressure. Temperature does, and R-410A answers with a much bigger number.
Reference Hint
Recovery equipment and recovery cylinders carry refrigerant specific ratings. R-410A requires equipment rated for its higher pressures.
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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