A technician arrives at a system that still holds part of its refrigerant charge and finds that nitrogen was added on top of it during an earlier visit. What is the concern about connecting the recovery machine and starting?
Correct Answer
D) The nitrogen will fill the cylinder as a gas that cannot be condensed
Nitrogen does not condense at the pressures and temperatures a recovery machine works with, so it collects as a gas in the top of the recovery cylinder. The pressure it adds pushes the cylinder toward the machine's high pressure cutout long before the cylinder holds its rightful weight of refrigerant, and it leaves the recovered refrigerant contaminated with non-condensables. That is exactly the condition a reclaimer has to correct before the refrigerant can be reused.
Why This Is the Correct Answer
Nitrogen is a non-condensable at recovery conditions. Pumped into a recovery cylinder it stays as gas above the liquid, raising cylinder pressure well beyond what the refrigerant alone would produce and stalling the machine on its high pressure cutout. The refrigerant underneath is then contaminated, which means it cannot be treated as clean product and has to be sorted out at a reclamation facility.
Why the Other Options Are Wrong
Option A: The nitrogen will condense with the refrigerant and dilute the oil
Nitrogen will not condense at these pressures and temperatures, so it never joins the liquid phase and never mixes with the oil.
Option B: The nitrogen will damage the recovery machine's compressor valves
Recovery machines pump nitrogen without mechanical harm. The problem is what happens in the cylinder, not what happens to the machine's valves.
Option C: The nitrogen will react with the refrigerant to form corrosive acids
Nitrogen is inert, which is why it is the accepted pressure testing gas. It forms no acids with refrigerant or with oil.
Memory Technique
Nitrogen refuses to lie down. It rides on top of the liquid and pushes the gauge up.
Reference Hint
Nitrogen mixed with refrigerant must be recovered, and it enters the cylinder as a non-condensable gas.
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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