A technician has finished pulling the liquid charge out of a large system, and the sight glass in the recovery hose has gone clear. What still has to be done before the system may be opened?
Correct Answer
C) Switch the machine over to vapor recovery and pull the remaining refrigerant down to the required level
Liquid recovery is fast, but it never gets everything. Once the liquid is gone the system still holds refrigerant vapor throughout, plus liquid dissolved in the compressor oil that will boil off as pressure drops. The job is finished in vapor mode, drawing the system down to the required recovery level for that appliance and verifying it holds there. Stopping when the liquid stops moving leaves a substantial amount of refrigerant in the system, which will simply be released when the technician breaks a connection.
Why This Is the Correct Answer
Vapor fills the whole volume of the system and refrigerant stays dissolved in the oil, so a large amount remains after the liquid phase is complete. Switching to vapor recovery and pulling down to the required level is what actually satisfies the recovery requirement before the system is opened.
Why the Other Options Are Wrong
Option A: Nothing further, because pulling the liquid out takes essentially the whole charge with it
A system with the liquid gone still holds a full volume of vapor plus refrigerant dissolved in the oil, and all of it escapes at the first broken connection. A clear sight glass means the liquid is gone, not the charge.
Option B: Break the remaining vacuum with dry nitrogen and then run the liquid recovery pass over again
Nitrogen belongs in leak testing and evacuation sweeps, not in the middle of a recovery. Adding it here dilutes refrigerant that still has to be captured and lengthens the job.
Option D: Start the appliance's own compressor and let it push the remainder of the charge into the recovery cylinder
The appliance compressor is not certified recovery equipment, and running it as pressure falls risks damaging it while moving very little refrigerant. The recovery has to be finished through the machine.
Memory Technique
Liquid for speed, vapor to finish. The sight glass clearing is halftime, not the final whistle.
Reference Hint
40 CFR 82.156 requires the appliance to be evacuated to the applicable recovery level before it is opened for service.
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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