Spunding valve but without the pressure gauge?

I was thinking about building an 'ultra' cheapo spunding valve system for pressure fermentation but leaving the pressure gauge out of it and just using one of these (plus some hose and a barb or two):

http://www.grainger.com/Grainger/CDI-CONTROL-DEVICES-Variable-Pressure-Relief-4TK26?Pid=search

Could I calibrate the position on the pressure relief valve (say to 20 psi) using my CO2 tank/regulator, and just leave the valve in position and use it without any kind of attached pressure gauge? The main problem I see is that the pressure marked on the valve is waaay inn inaccurate, but if I set it correctly once, it should work right? Why do people always add a pressure gauge to their setup?

scone said:

Why do people always add a pressure gauge to their setup?

Click to expand...

The same reason people use hydrometers and refractometers.

Because visual verification is always better than assumption.
If you are off on your calibration, you could easily kill your yeast by having too much pressure build up in the keg(I assume you are using a keg).

A gauge is cheap on ebay...and a three way adapter is also cheap.
Put out the extra money and get a proper spunding valve put together.

E-Mursed said:

The same reason people use hydrometers and refractometers.

Because visual verification is always better than assumption.
If you are off on your calibration, you could easily kill your yeast by having too much pressure build up in the keg(I assume you are using a keg).

A gauge is cheap on ebay...and a three way adapter is also cheap.
Put out the extra money and get a proper spunding valve put together.

Click to expand...

Points well taken, but I've seen several complaints about the cheap ones corroding after a year or two in the lagerator. I also wonder about the accuracy of a $7 gauge, and it seems to me that it's not really required as long as you set the variable pressure relief valve properly.

As far as dying yeast, I'd be far more worried about the thing clogging and the regulator exploding (or the keg even), though I've also read that yeast stop being active around 30 psi...

I assumed cheap was your goal in not using a gauge - I bought quality myself.

As far as your keg exploding...cornies are rated to 130psi.

I use a blow off for the first 48 hours and then put my spunding valves on and have not had a clog.

Yeah totally. My point being that if I buy a good gauge, the project is like $75+ after all is said and done. I was trying to think of a way to do this without spending so much, and figured that a $7 gauge is worth about what you pay for it, so I'd rather just not even get one if it's a piece of junk and it's possible to do this without it.

I'll be fermenting in a pony keg, so it's only rated to 60.

So here's a question... do you find yourself messing with the valve much, or does it's position keep a tight correlation with the pressure you read off the gauge?

I use the same valve, but out of the box 20 psi will not be 20 psi on the visual gauge. You can calibrate the valve, but I just adjust to my gauge.

You don't really need an expensive gauge for what you are doing. The gauge just needs to read pressure between 0 - 30 psi. If you do this right, there never is any krausen in the valve assembly to clog it.

If you are an engineer type, I apologize for wasting your time trying to talk you down to simplicity. It really doesn't have to be that complicated.

Once set and fine tuned, it holds steady pressure.

E-Mursed said:

If you are off on your calibration, you could easily kill your yeast by having too much pressure build up in the keg(I assume you are using a keg).

Click to expand...

scone said:

As far as dying yeast, I'd be far more worried about the thing clogging and the regulator exploding (or the keg even), though I've also read that yeast stop being active around 30 psi...

Click to expand...

The yeast won't die above 30 psi, and they won't stop being active either. What they will do is get stressed and start producing all sorts of nasty off flavors if they're still near peak fermentation, while continuing to build pressure in the keg. When people carbonate homemade soda with yeast the pressures get in excess of 60 psi, and will keep going higher than that if it's not put in the fridge.

scone said:

So here's a question... do you find yourself messing with the valve much, or does it's position keep a tight correlation with the pressure you read off the gauge?

Click to expand...

I sometimes set the pressure to 15 psi during fermentation, and then crank it up to 30 just before fermentation is finished to carbonate the beer. Higher pressure during the most active stage of fermentation can cause the yeast to produce some off flavors. I've read that for some yeast strains this can be anything over 15 psi, which is why I use 15 psi for the majority of fermentation. I also adjust the pressure way down when using it for counterpressure transfers. If you don't plan on carbonating the beer from fermentation, or using the spunding valve for counterpressure transfers, you could probably just get it set right once, and leave it there.