Before recovering refrigerant into a recovery cylinder that has never been used, a technician evacuates the cylinder with a vacuum pump. Why does that step matter?
Correct Answer
A) Any air left in the cylinder becomes a non-condensable that contaminates the recovered refrigerant and drives cylinder pressure up
Whatever is already in the cylinder stays in the cylinder once recovery starts. Air and the nitrogen holding charge do not condense at any temperature the cylinder will see, so they sit on top of the liquid refrigerant and raise the pressure the recovery machine has to push against. That slows the job and can stall it entirely. The contamination also follows the refrigerant to the reclaimer, where non-condensables have to be removed before the product can be brought back to specification. Five minutes with a vacuum pump avoids all of it.
Why This Is the Correct Answer
Air and nitrogen are non-condensable at cylinder conditions. Left in place, they add their own partial pressure to the refrigerant's saturation pressure, so the cylinder reads high, the recovery machine works against a larger head, and the recovered refrigerant arrives at the reclaimer contaminated.
Why the Other Options Are Wrong
Option B: The vacuum drawn in the cylinder is what pulls refrigerant out of the appliance, and the recovery machine only opens a path for it to follow
The recovery machine is a compressor, and it is what creates the pressure difference that moves refrigerant. It does that whether the cylinder started under vacuum or not, so the evacuation is about purity rather than pull.
Option C: An unevacuated cylinder may legally be filled only to half of its rated capacity rather than the usual eighty percent
No rule sets a fill limit that depends on whether the cylinder was evacuated. The eighty percent limit is fixed, and it exists to leave room for the liquid to expand as it warms.
Option D: Evacuating the cylinder resets the tare weight stamped on its collar so the scale reading stays accurate
Tare weight is a physical property of the empty cylinder, stamped at manufacture and used as the subtraction point on the scale. Pulling a vacuum removes gas, not steel, so nothing about the stamp changes.
Memory Technique
Whatever is in the bottle stays in the bottle. Empty it before you fill it.
Reference Hint
Recovered refrigerant sent for reclamation must be brought to the industry purity standard, 40 CFR 82.157. Non-condensables are a tracked contaminant.
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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A packaged rooftop unit was fully assembled and charged at the factory, and the nameplate lists a twelve pound charge of R-410A. Which certification applies when a technician opens that sealed refrigerant circuit?
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