A system has been pressurized with dry nitrogen for a leak test, and a technician sweeps an electronic refrigerant detector along every joint without getting a single alarm. What does that result tell the technician?
Correct Answer
D) Nothing at all about the joints, because an electronic refrigerant detector does not respond to nitrogen
An electronic refrigerant detector senses refrigerant molecules. Nitrogen is what makes up most of the air the detector sits in all day, so it produces no response whether it is leaking or not. Sweeping a nitrogen-charged system with one of these instruments is a wasted trip regardless of how good or bad the joints are. Leaks on a nitrogen charge are found with bubble solution brushed on the joints or with an ultrasonic detector, both of which respond to gas escaping rather than to the identity of the gas.
Why This Is the Correct Answer
The detector is built to alarm on halogenated refrigerant molecules. Nitrogen is the main component of ordinary air and produces no signal at all, so a silent detector on a nitrogen charge is not evidence of anything about the system.
Why the Other Options Are Wrong
Option A: Every joint is tight, so the system can be evacuated and charged with no further leak testing
A silent detector on a nitrogen charge proves nothing, and moving straight to evacuation and charging is the exact error this scenario is built around. The joints have not been tested at all.
Option B: The nitrogen test pressure is too low for the detector to sense anything escaping from a joint that small
Pressure is not the issue. Nitrogen blowing hard out of a wide open joint would still leave a refrigerant detector silent, because the instrument responds to the gas, not to the flow.
Option C: The detector's sensing element has failed, so a new sensing tip has to be fitted before testing
The instrument is working correctly. A detector that stays quiet in the presence of a gas it was never built to sense is behaving as designed, so a new tip changes nothing.
Memory Technique
Nitrogen is just air's main ingredient. A refrigerant sniffer has nothing to sniff.
Reference Hint
Leak detection and verification requirements appear in 40 CFR Part 82, Subpart F; the method must be capable of detecting the gas actually in the system.
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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