Recovery has stalled because pressure in the recovery cylinder has climbed until the machine can no longer push refrigerant into it. What is the correct way to get the transfer moving again?
Correct Answer
A) Cool the recovery cylinder, for instance by standing it in a tub of cool water, so the pressure inside it drops
Cylinder pressure is set by the saturation temperature of the liquid inside it. Cooling the cylinder lowers that saturation pressure, which restores the pressure difference the recovery machine needs to keep pushing refrigerant in. A tub of cool water or ice water around the cylinder is the standard field fix, and swapping to a fresh cylinder works too. Warming the cylinder does the opposite of what is needed, bleeding it to atmosphere is a prohibited release, and walking away only lets the pressures come back together with the charge still in the appliance.
Why This Is the Correct Answer
Lowering the cylinder's liquid temperature lowers its saturation pressure directly, which reopens the pressure difference the machine is working across. It also condenses vapor in the cylinder headspace, giving the incoming refrigerant somewhere to go. Cool water is effective, cheap and safe.
Why the Other Options Are Wrong
Option B: Warm the recovery cylinder with a heat source so the refrigerant inside expands and makes room, freeing space
Heat raises the cylinder's saturation pressure, so the machine pushes against an even larger head and no space is freed. On a cylinder near its fill limit it can also lift the relief device.
Option C: Crack the cylinder valve briefly to bleed off the pressure that has built up inside
Bleeding a cylinder to atmosphere is a knowing release and is prohibited however brief it is. It also throws away refrigerant the technician is being paid to capture, so it repairs nothing.
Option D: Disconnect the machine and let the appliance sit overnight until pressures equalize on their own, then resume in the morning
Letting the system sit does not move refrigerant out of the appliance. Equalized pressure means the transfer has stopped for good, so returning in the morning finds exactly the same stalled job.
Memory Technique
Stalled recovery? Cool the can. Never heat it and never bleed it.
Reference Hint
Knowingly venting refrigerant is prohibited under 40 CFR Part 82, Subpart F. Cylinder pressure follows the saturation temperature of the liquid inside.
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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