My Reg pressure climbs in cold temps

[Bob_O]

New Crown 22.....about 1,000 pellets through it.

Going from 60-65*F in my basement shooting over the chrono, the reg stays right where I set it, the latest at 130bar.

When I go out in the cold, 10-20*F, the reg pressure will read up to 5bar higher. It stays like this shot after shot.

When I get the gun back home and warmed up, the reg will be back to what I set it to. This has happened at 140 and 145bar also.

Anyone have any input on this?

 

[heavy-impact]

Steel gets more rigid in the cold so maybe the belleville washers don't flex as easy.

 

[ackuric]

belleville washer hardness changing based on temp? meaning it has to work harder to compress them ie: more pressure

 

[ackuric]

I'd get some boot/glove warmers if it really bothers you and make a little wrap you can put them in that surrounds your plenum/reg area...JMO!

 

[Bob_O]

The only part that bothers me is the change in performance, as in my tune will be affected. It would be like changing the reg pressure without fine tuning the hammer spring tension.

I will have to dig out my old notes and see if I have a tune at 135bar. If so, it could be that I just increease the hammer spring tension by one step to compensate.

 

[Guest]

My money is on the gauge. Small metal parts directly exposed to the cold. Maybe test over a chrony and check velocity in the cold to see if your reg is the issue.

 

[broekzwans]

It's probably a combination of the BV washers with the pressure gauge. The accuracy of a pressure gauge is specified in a fixed temperature and deviating from that temperature creates a change in accuracy. Since those small pressure gauges are already specified as 4 to 6 % accuracy that causes quite an influence.

What you can try is measuring it with a digital pressure gauge (which is also ideal for accurately measuring the regulator pressure). The temperature stability of the digital versions is in most cases better than the analog ones. I have one of these: digital pressure gauges on ebay. I checked a couple of them with a calibrated pressure gauge and they are very good for the price, their absolute error was within ±1 bar. They advertise with 1/4 NPT but all 4 I got were 1/4 BSP so it's better to ask before buying. Just put an 1/4... to 1/8 BSP adapter onto it and you can screw it into the pressure gauge hole of your Crown

 

[allenbowles]

hi bob,my 177 crown done the same on my tank gauge,i switched gauges and it done the same on the reg. side...tank side ok...hope this helps.....

 

[jmmartinez573]

I tuned my brod in 70 degree weather. Reg setting was 1850-1900.



in 30-40 degree weather my plenum dropped to 1750. Dropped my FPS by 15-25.