Elastomer Seals & Gaskets

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  • Evacuating R‐22 can exercise existing elastomer seals & gaskets causing leaking upon re‐charging.
  • Evaluate high risk seals & gaskets prior to conversion and replace as needed (see below).
  • Tighten terminal gaskets & compression fittings.
  • Leak check seals & gaskets post conversion.


Elastomer seals and gaskets can react harshly to R‐22 and degrade over time. Rarely does this cause leaks, but the potential for leaks is much greater after a system has been evacuated and re‐charged. This makes proactively identifying leaking seals and gaskets much more difficult.

Whenever R‐22 is recovered, the elastomer seals and gaskets should be evaluated on a case‐by‐case basis taking into consideration the likelihood of the seal to leak, the critical nature of the seal if it were to leak (meaning the refrigerant must be recovered to replace), and the cost associated with losing refrigerant charge and call‐back labor, versus preemptive replacement.

Best Practices

  • Evaluate which seals are critical.
  • Evaluate which seals + gaskets are at highest risk of leaking prior to conversion (high pressure seals are more likely to leak): Receiver gaskets, compressor shaft seals, terminal gaskets, etc.
  • Decide which seals are best candidates for pre‐emptive replacement. Consider the cost of lost refrigerant and required labor if system leaks

Additional Tips

  • If system holds low side nameplate pressure but fails to pull in sufficient vacuum, gaskets or seals might be leaking.
  • If the vacuum pulls down and “bottoms out,” break the vacuum with nitrogen, or triple evac.
  • If the vacuum still doesn’t pull down – check seals & gaskets, replacing where needed.


Figure 1. Leaking Ball Valve.

Figure 2. Terminal Gaskets.