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The hot water tank in your home has a PRV, set up so that if the pressure inside the water tank gets too high, for any reason, it will open and vent the hot water and steam to atmosphere.
This usually means all over your floor! : -)
As it pertains to your compressed air system and your air compressor however, you’ll want to be sure that the receiver / air tank / reservoir into which your compressor assembly pumps air, has a working PRV.
When your air system calls for air, your compressor “kicks-in”. It gulps in free air through it’s intake filter and “scrunches” into your receiver, continuing the process until the pressure inside the receiver reaches a high “set point” pressure level. At this time, your compressor should stop and “unload”.
What if it doesn’t?
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Compressed air is “explosive” when it’s released suddenly, and you sure don’t want to be anywhere around if a compressed air receiver should disintegrate due to unsafe high pressure levels inside. It’s a bomb!
To help ensure that this doesn’t happen the compressed air receiver has a PRV either on the top to one side or the other, or as part of the check valve / pressure switch / PRV assembly where the air from the compressor head enters the air tank.
Some of them look a bit like this.
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There’s a ring on the end of the PRV which, when pulled, will allow air from the receiver to vent to atmosphere.
Some PRV’s rely on ‘sticktion’; that’s friction between it’s parts to generate enough force to overcome movement of the internal piston to keep the PRV closed.
Others have an internal spring performing the same task.
When the pressure inside the reservoir reaches the PRV’s set point, the air pressure acting on the piston inside the PRV overcomes it’s “sticktion” or spring pressure, forcing the piston out, and opening the valve to atmosphere.
While I have never had a PRV on a receiver open due to over-pressure inside the tank, having the PRV there provides a critical and mandatory safety assurance.
For the same reason, you never want to have a source of pressure that can increase in a system without a PRV in place.
And it doesn’t hurt to check them every once in a while, Give the ring a pull to make sure it releases.
It’s cheap insurance, and could save a life.
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