Question for spunding valve builders

[Horseflesh]

The other day I built a spunding valve as described here:

http://www.homebrewfinds.com/2011/02/build-spunding-valve.html

When I pop the valve off a pressurized keg, the gauge continues to show pressure as you'd expect... but the assembly does lose pressure over time, about 5 PSI per day. So the assembly isn't airtight... but is it close enough?

The gas volume in the detached assembly has got to be very small compared to the headspace in a keg. If I submerge the whole assembly while pressurized, I can't even see bubbles.

Is it good 'nuff or should I try to tighten all the parts more? I'm not sure I can turn anything much further, it's all very tight already.

 

[homebrewer_99]

Correct me if I'm wrong, but the Spunding Valve is a pressure release valve that releases any over pressure in the keg. If there is no gas line connected to the keg then I would think any "loss" would be from the air space in the keg and absorbed by the beer.

Someone please set me straight with this if I am wrong. It's always been a subject I wanted to do more reading on.

 

[Horseflesh]

I this case the whole spunding valve was detached from the keg, to check the assembly for leaks. It's like how the gauge on your CO2 tank still reads at your keg pressure when you turn everything off and detach it.

If the spunding assembly leaks, then you may over time vent to a lower PSI than you desire.

But in my case, the leak is so slow I wonder if it matters.

 

[beermanpete]

The leak you are detecting may be the poppet valve in quick disconnect. If so, it won't leak when installed on the keg. Try a pressure test that includes the keg.

 

[Horseflesh]

I cranked the fittings down more, and I don't think they can get tighter... but it's still losing pressure at about the same rate. Hopefully it's the QD as you suggested.

 

[FunkedOut]

I have the same behavior as you.
When connected to a keg with active fermentation, it doesn’t matter.
When the yeast are done venting co2, it will matter. That’s when I disconnect it from the keg.

 

[Horseflesh]

Thanks for the sanity check!

 

[Sadu]

When I got my spunding I was told they always leak to some small degree. So you just remove it when fermentation is over and it's not a problem.

 

[divrack]

Thanks for the sanity check!

If guess it's from the poppet mainly. They aren't the best when off for sure.