A technician front seats the suction and discharge service valves on a semi-hermetic compressor, isolating it from the rest of the system. What has to happen before the compressor is unbolted and lifted out?
Correct Answer
C) The refrigerant shut inside the compressor must be recovered through its port
Front seating the service valves does not empty the compressor, it seals a charged vessel. The shell still holds refrigerant vapor and refrigerant dissolved in the oil, and unbolting the flanges would release all of it. The compressor has its own gauge port between the valve seats, and the recovery machine is connected there to pull that isolated section down to the level required for the appliance before anything is unbolted.
Why This Is the Correct Answer
Front seating traps refrigerant inside the compressor rather than removing it. The shell holds vapor at whatever pressure was there when the valves closed, plus refrigerant dissolved in the oil that will boil off as the pressure drops. Recovering through the compressor's own service port brings that isolated section to the required level so the flanges can be broken without a release.
Why the Other Options Are Wrong
Option A: The rest of the system must be evacuated to the required level as well
The rest of the system was deliberately isolated so it would not have to be evacuated. Only the section being opened has to reach the level.
Option B: The valves must be back seated so pressures equalize across the compressor
Back seating would reconnect the compressor to the system and undo the isolation, putting the whole charge back in the section about to be opened.
Option D: The compressor oil must be drained into the recovery cylinder with the charge
Oil is drained into a container for waste handling, never into a recovery cylinder. Mixing oil into recovered refrigerant contaminates the cylinder.
Memory Technique
Front seating locks the door with the refrigerant still inside the room. Somebody still has to let it out.
Reference Hint
An isolated component must itself be evacuated to the level required for the appliance before it is opened.
More epa-608-type-2 Questions
A walk-in cooler condensing unit holds a full charge of twenty-five pounds of R-404A, which is below the fifty pound threshold that brings an appliance under the leak repair provisions. What still applies to this unit?
An office building has thirty water source heat pumps on a common water loop, and each one left the factory assembled, hermetically sealed and charged with four pounds of R-410A. How is one of those units classified?
A data sheet for an unfamiliar refrigerant lists a boiling point of about fifty-five degrees Fahrenheit at atmospheric pressure. What does that tell a technician holding Core and Type II certification?
A technician holds Core, Type I and Type III certification and is sent to recover the charge from a twenty ton rooftop unit charged with R-410A. What does that combination of sections allow on this job?
A fleet garage technician holds only the vehicle air conditioning certification issued under Section 609 and is asked to recover the charge from the shop's own rooftop air conditioner. What does that credential allow?
A split system's outdoor unit, indoor coil and the line set the installer ran and brazed between them are being considered. For the purposes of the refrigerant rules, what makes up the appliance here?
On a new installation the line set is brazed to a factory charged outdoor unit and an indoor coil shipped under a nitrogen holding charge, with the outdoor unit's service valves still closed. What does the recovery requirement call for before that brazing?
A rooftop unit's data plate has weathered until the charge figure cannot be read, and the technician needs the full charge to place the appliance under the evacuation and leak provisions. Where should that figure come from?
A computer room air conditioning unit holds forty pounds of R-407C and connects to a remote air cooled condenser through refrigerant piping run and brazed by the installer. How is that unit classified?
A shop's office manager, who holds no technician certification, is sent to a supply house to pick up a new recovery machine for the commercial crew. What does the sales restriction require at that counter?
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