Why is my pressure regulator drifting down?

[steves1080]

I have a self-venting single-stage pressure-reducing regulator that takes ~2500 psig and steps it down to ~1500 psig (here is a link with the specific details of the hardware if interested: http://www.items.se/Dokument/44-1300_10061107.PDF). I experienced some odd behavior recently where the pressure transducer in the downstream process piping began a steady decline at ~50 psi/hour after remaining stable for ~3 hours. This pressure should be stable since the GN2 sitting in this line should be static (nothing is actually flowing during this time). I cannot seem to explain why this is occurring. Upstream of the regulator, pressure is being supplied to multiple other locations where it does continuously flow. Any insight as to what is occurring would be greatly appreciated.

Thanks

 

[steves1080]

A fellow coworker seems to think that condensate is accumulating and causing the vent port to become clogged, but that would only sort of make sense to me if the outlet pressure was rising. This reg is located in an enclosed panel in an outdoor environment. It is not uncommon for there to be condensation on the pipes in this panel.

 

[Travis_King]

It's air or steam or what?

 

[steves1080]

It's GN2

 

[Bandit127]

It's GN2

Gaseous Nitrogen I presume.

 

[steves1080]

Correct

 

[Bandit127]

I would check your gas is warm before getting to the regulator. It might be thermal contraction as the gas cools the regulator - or cold gas upstream is cooling the regulator via the pipes.

Wouldn't worry about water (ice) inside as nitrogen gas contains very little of it.

 

[Baluncore]

How do you know that it is not a fault with the downstream gauge or transducer ?
I have seen that sort of thing happen when a gauge leaks and builds up pressure on the back of the gauge.
Can you exchange test the gauge ?