Which of these may be released without violating the venting prohibition?
Pure nitrogen is one example. Carbon dioxide, nitrogen and water are exempt from the venting prohibition in any application. A few other substitutes are exempt only in the equipment the rule lists.
- R-410A drained from a system before a coil change
- R-134a from a disposable cylinder heel
- Pure nitrogen used to pressure-test a line setCorrect answer
- R-22 removed during an oil change
Why “Pure nitrogen used to pressure-test a line set” is correct
40 CFR 82.154(a)(1) lists substances exempt from the venting prohibition, including nitrogen in any application, carbon dioxide and water. Pure nitrogen used for a pressure test can be released. HFCs and HCFCs must be recovered.
Source: 40 CFR 82.154(a)(1)
Why the other answers are wrong
- R-410A drained from a system before a coil change — R-410A is a non-exempt substitute; removing it before opening the system means recovering it, not venting it.
- R-134a from a disposable cylinder heel — The heel of a disposable cylinder must be recovered, not vented.
- R-22 removed during an oil change — Refrigerant in oil must be recovered; oil changes have their own pressure limit.
The source, word for word
Carbon dioxide in any application;
Nitrogen in any application;
De minimis releases associated with good faith attempts to recycle or recover refrigerants are not subject to this prohibition.
The exemptions
Most of the list is tied to an end-use, so the same substance may be exempt in one appliance and not in another.
| Substance | Exempt in |
|---|---|
| Carbon dioxide, nitrogen, water | Any application |
| Ammonia | Commercial or industrial process refrigeration, or absorption units |
| Hydrocarbons | Industrial process refrigeration that processes hydrocarbons |
| Propane (R-290), isobutane (R-600a), R-441A | Listed equipment such as household refrigerators and freezers |
| Ethane (R-170) | Very low temperature refrigeration and non-mechanical heat transfer |
De minimis is different
A de minimis release is not an exempt substance. It is a small loss of a regulated refrigerant during a good-faith recovery, while following the required practices with certified equipment and certification. The small loss when connecting hoses during proper recovery is an example.
Keep practicing
- EPA refrigerant recovery rules
- Does the venting ban cover HFCs?
- Why emptying a recovery cylinder outdoors is venting
- The R-600a exemption in household refrigerators
- EPA 608 Core practice test
Unofficial, not affiliated with the EPA or any EPA-approved certifying organization. Questions are original practice written from public EPA material, not real exam questions.