Spunding Valve

[malt junkie]

1m = 10kpa... luck with that

 

[wynnum1]

So is that plus atmospheric pressure and its measured with atmospheric pressure as zero on the pressure meter

 

[pcqypcqy]

So is that plus atmospheric pressure and its measured with atmospheric pressure as zero on the pressure meter

No, the keg with nothing on it has atmostpheric pressure pushing on the outside of it (and the inside). So all you're measuring is the additional pressure over that (often called gauge pressure).

3.4 metres to get 5 psi, so maybe not practical.

On the other hand, if you used mercury, it would be liquid at room temperature and you'd only need 258mm of it! (link)

 

[malt junkie]

Interestingly the pressure would directly relate to the Gravity of the liquid.

 

[klangers]

Yes, static pressure is height (m) x density (kg/m3) x acceleration due to gravity (m/s2) = Pa (N/m2)

 

[Hpal]

This one is pretty munted. It is the one that looks like an A type but isn't so I am going to put a corny top on it

at least you can get your arm in to clean then, it's the way to go.

 

[peteru]

Yes, static pressure is height (m) x density (kg/m3) x acceleration due to gravity (m/s2) = Pa (N/m2)

Taking that info down the practical path, you could use a piston with a weight on it. Hydraulics, here we come! :super:

 

[wynnum1]

No, the keg with nothing on it has atmostpheric pressure pushing on the outside of it (and the inside). So all you're measuring is the additional pressure over that (often called gauge pressure).

3.4 metres to get 5 psi, so maybe not practical.

On the other hand, if you used mercury, it would be liquid at room temperature and you'd only need 258mm of it! (link)

Pvc pipes come in 6 meter lengths so 3.4 meters is not a problem .

 

[pcqypcqy]

Pvc pipes come in 6 meter lengths so 3.4 meters is not a problem .

Pics or it didn't happen

I'd be keen to see how it goes. You doing this outdoors? Tall shed?

 

[klangers]

Taking that info down the practical path, you could use a piston with a weight on it. Hydraulics, here we come! :super:

Indeed, this is how a lot of hydraulic accumulators were designed prior to 1950s.

Honestly though, it's a shitload easier and cheaper buying a good spunding valve than trying to rig up some hydraulic rig to apply backpressure to your keg. The CO2 needs to be exhausted, so if you were going down a hydraulic accumulator route, you'd need to have enough volume in that water column to take up the exhausted CO2. In addition, it would need to be a closed system (not open to atmosphere). If it's open at the end, CO2 would just bubble up through the water and/or push out the water. If it's closed, then the volume would need to expand. So in order to do this with a water column, you'd have to have a flexible membrane between the keg CO2 and water column. Then the CO2 emerges and pushes against the static water pressure without mixing with it.

You'd be better off connecting your full keg gas to an empty keg. Then the CO2 will gradually fill the empty keg and headspace in full keg and increase the pressure in both. It's possible to calculate this extra volume you need.

 

[Mardoo]

Indeed, this is how a lot of hydraulic accumulators were designed prior to 1950s.

Steampunk pressurised fermenting!

 

[mtb]

Steampunk pressurised fermenting!

Maybe "Steam Ale" will finally have a basis on which to define itself as an actual style

 

[rude]

Looks good Crusty so I've got myself an address in the States through shop mate cheers

Carted a valve , gauge , tee piece all 1/4 npt just need 1/4" npt male to the thread size of gas disconnect female ????

7/16 usf or usn ???

Shop Mate worked but ended up with 2 parcels instead of 1, blew that

Had to pay 2 lots of postage as Shop Mate dont repack

Expensive valve this one just hope its better than the KK one if not I lose

 

[pcqypcqy]

Indeed, this is how a lot of hydraulic accumulators were designed prior to 1950s.

Honestly though, it's a shitload easier and cheaper buying a good spunding valve than trying to rig up some hydraulic rig to apply backpressure to your keg. The CO2 needs to be exhausted, so if you were going down a hydraulic accumulator route, you'd need to have enough volume in that water column to take up the exhausted CO2. In addition, it would need to be a closed system (not open to atmosphere). If it's open at the end, CO2 would just bubble up through the water and/or push out the water. If it's closed, then the volume would need to expand. So in order to do this with a water column, you'd have to have a flexible membrane between the keg CO2 and water column. Then the CO2 emerges and pushes against the static water pressure without mixing with it.

You'd be better off connecting your full keg gas to an empty keg. Then the CO2 will gradually fill the empty keg and headspace in full keg and increase the pressure in both. It's possible to calculate this extra volume you need.

I don't know that it's quite the same as an accumulator.

If you had a column of water that was open to the atmosphere, this should provide a constant back pressure on your system. Gas above this pressure would escape into the water and bubble away.

 

[klangers]

I don't know that it's quite the same as an accumulator.

If you had a column of water that was open to the atmosphere, this should provide a constant back pressure on your system. Gas above this pressure would escape into the water and bubble away.

... but it won't. If the keg was just liquid, then yes it would work. But CO2 is less dense that the water, so all that will happen is either:

• You put the column of water entering the bottom of the keg (dip tube). All the CO2 floats to top of the keg. Unless you have the perfect amount of sugar, the excess CO2 will build up and displace the water in the column by pushing beer out of the keg up the column. Yes your pressure was constant but now your volume is less
• You put the column of water entering the top of the keg (no dip tube). All the CO2 (less dense than liquid water) bubbles up and you have flat beer. J

You need to exhaust the right amount of CO2. It's not just about static pressure.

 

[Mardoo]

OK, I had mentioned I would post some papers I had saved. Turns out they were on my old computer that died and didn't make it across to the backup in time.

However, I've hunted down a few papers on the topic of pressurised fermenting, which I'm currently going through.

The TLR is that as long as you keep pressure below 20PSI/138kPa, it's been shown in laboratory and actual practice that you will see significant suppression of esters, and be able to ferment at higher temperatures before fusel alcohol production kicks in. This is due to the higher volume of CO2 that is allowed to remain in solution at higher pressures. Yeast growth is inhibited to some degree, but it is said to be likely that it is the cap on yeast growth that allows the suppression of esters and fusels. Many, many major breweries use pressurised fermentation of lagers, so it can't be that much of an issue with the yeast.

There is likely some reduction in head formation for beers fermented at higher pressures. I'm trying to chase up a paper on that specific topic, but have yet to track one down that's not behind a paywall. Here's one interesting thing that's referenced. For a given volume of wort, no matter what the gravity of that wort, the amount of head-forming proteins will be exactly the same. 20L of 15P wort will have exactly the same amount of head-forming proteins as 20L of 25P wort. Weird. So, if you brew high-gravity and dilute back to get increased volume, you're likely to see a reduction in head formed.

I'm including a very interesting paper on high-gravity brewing, since some folks in this and the pressurised fermenting thread have mentioned brewing high to dilute low.

So, here are the papers. I haven't yet finished going through them so there may be more of interest that one of youse wants to point out, as well as any shortcomings in my descriptions.

And...GOOGLE SCHOLAR ROCKS!!! If you're into searching out actual research, get on it.

View attachment Improving Yeast Fermentation Performance.pdf
View attachment CO2 Pressure and Ester and Fusel Formation.pdf
View attachment Yeast Response to Fermentation Under Pressure.pdf
View attachment Controlling Yeast Fermentation.pdf

 

[pcqypcqy]

... but it won't. If the keg was just liquid, then yes it would work. But CO2 is less dense that the water, so all that will happen is either:

• You put the column of water entering the bottom of the keg (dip tube). All the CO2 floats to top of the keg. Unless you have the perfect amount of sugar, the excess CO2 will build up and displace the water in the column by pushing beer out of the keg up the column. Yes your pressure was constant but now your volume is less
• You put the column of water entering the top of the keg (no dip tube). All the CO2 (less dense than liquid water) bubbles up and you have flat beer. J

You need to exhaust the right amount of CO2. It's not just about static pressure.

OK, I think I'm with you now.

I think in my mind I'm picturing a system where instead of the elastic compression held in the spring to apply back pressure to the valve, it's a column of water. If you could run it through a one way valve that only opens when the C02 pressure is greater than the water pressure, then you'd have the same effect.

If you have this one way valve, then it does become a matter of just maintaining the static pressure inside the fermenter, which is obviously much simpler than designing an accumulator.

 

[wynnum1]

At major breweries is there a limit on the depth of tanks to limit pressure at the bottom of the tank.

 

[peteru]

Yes. Lagering tanks are usually up to about 5m in diameter. They are often configured in stacks and are typically long cylinders lying on their side. I'm not sure if it's specifically to limit the pressure or whether it's done to address any particular yeast requirements. It could just be simple manufacturing constraints or material constraints. I've been to a number of breweries where the lagering tanks are built first, then the building that houses them is built around them - they can get massive.

 

[technobabble66]

For the water pipe setup, could you get your 3.5m pvc pipe full of water and run your 4mm venting hose from the keg to the top of the pipe, then down the inside of the pipe to the base where it's left open.
So as the co2 builds up in the keg, it gradually pushes down the water in the hose until it gets to the bottom, then bubbles up and away.
This way, there's likely to be little relative absorption of the co2 into the water, as its only exposed to a tiny amount of water in the 4mm hose. The upwards pressure of the water in the hose provides the resistance, and the water won't flow back into the hose past the top water lever in the pipe.
You still need 3.5m of pipe and ~8-10m of 4mm hose, but I think it'd work sufficiently. Or have I missed something?

Obviously you'd need to attach the end of the hose to the bottom of the pipe somehow or find some way to hold it down. And maybe put a one way valve in the hose just to ensure mr cockup doesn't visit.