Force carb'ing and PRVs

[Supernaut]

Hello All,

I'm force carbonating a few tanks with 40 PSI on the carb stone and 15 PSI maintained on the head. Right now I am maintaining that 15 PSI by adjusting the PRV but I'm getting (read: losing) a lot of foam through the PRV and all over the place.

Do folks put a valve on the racking arm and pump the gas into a bucket via tubing just like during primary? Or is force-carbonating a messy business and I should just live with it?

Out of curiosity, how long would it take to carbonate a 7 BBL serving tank simply by holding the tank pressure @ 15 PSI? About a week? </guess>

Thanks!

[dick murton]

To me, it looks like the pressure at the carb stone is FAR too high. You only want a dribble going through there, or you end up washing most of it straight out again - as you are finding. However, since I haven't carbonated in tank for literally years, have a look at all the discussions on this site. I am sure that others with more recent small brewery experience will be able to guide you better.

One key aspect is the temperature. If you want to dissolve much gas, then the beer has to be cold. Again, lots of discussions about this on the site.

If you want an equilibrium table, have a look on the Meheen website as there used to be one on there - temperature / pressure and CO2 content.

[Supernaut]

Beer is at about 35F. And yeah, the input to the carb stone was way too high pressure. I hope I didn't over-carb. Bleeding some head pressure now....

Looks like "15 psi in, 15 psi-ish, out".

[kugeman]

Dick has it right. You should start off by pushing at 10-12 psi. When that reaches a balance then increase the pressure to 15 or so. Keep raising it slowly until you reach a tank pressure of 15 psi. You'll probably never end up setting the regulator above 25 but it depends on how much resistance you have. Once you've the tank at 15 psi I would slowly bleed CO2 out of the top of the tank, rather than using your PRV to do that for you. The PRV will work, but it really should be used as a safety valve, not an over-pressure relief. It is possible that the PRV could malfunction and you could risk damage to the tank or yourself. It should work, but it's just safer to bleed the CO2 manually.

You'll have to experiment a bit to find out how long it takes to carbonate a batch this way (usually this is called the "feed & bleed" technique). I would guess if your batch is fairly flat (about 2.0 vols) then it will take 4 or 5 hours to carbonate this way.

You should really never have foam or beer coming out the PRV. Unless your tank is filled to the brim. Carbonating the beer slowly shouldn't make the beer foam much.

[Supernaut]

Dick and Hutch,

Thanks for the replies. First carbonating day went well both w.r.t. carbonation and as a learning day. There are a lot of posts on probrewer on this topic, took a while to lug through them.

Yeah the foam through the PRV is a pain and it will be a pain to clean the valves but oh well. Live and learn! And practice, practice, practice.

Thanks again!

John

PS: Hutch - Michele and I loved the Brick Row Red. Good stuff.

[kugeman]

Thanks John. If I can be of any more help feel free to contact me.

hutchkuge@hotmail.com

[Supernaut]

Out of curiosity, what do you folks usually "set" the PRVs on your brite/serving tanks to? I'm going to dial them in at 16 PSI today, now that they're nice and clean again!

John

[CaptainEBC]

You should set your PRV no greater than your tank's rated working pressure.

Our tank's working pressure is around 20psi and we have the PRV set to crack at about 18.

[Horsepoorx2]

Formula . . .

Somewhere in my files I have a formula for this . . . It goes something like this: You want the pressure on the stone to be about 4 psi PLUS the target psi (15 in this case, I think) PLUS about 1 psi per foot of head. IOW, if the height to the top of your beer in the tank is four feet above your stone, you would need 4 + 4 + 15 = 23 psi on the stone. I'm not sure I have the head and basic stone pressures correct, but the principle of the formula is right. If I find the file, I will post it.

[Supernaut]

There is a nice write-up on Meheen's website which I had forgotten about.

http://www.meheen-mfg.com/tankcarb.html

Thanks!

John

[Horsepoorx2]

That's it!!! I just found it and was going to post the very same link.

[theBrewMeister]

Just wanted to chime in here real quick.

An old German brewer told me once, that ever bubble of foam you create while carbonating will never be able to be a bubble again. The protein breaks down and that's it. Keep in mind, in Germany they can't force carb so take this for what it's worth, but I live and die by this in my brewery.

The key is to carbonate as absolutely slow as possible and never allow for foam to break the surface tension of the beer. If you have any foam, you've gone too fast, and all youre doing is wasting gas.

As for the above post about base pressure on the stone, that would depend on the "break pressure" (the amount of pressure required to break the surface of the sintered stone) of your particular stone. Most stones have a break pressure @ around 4 or 5 psi. Meaning, it takes at least 4 or 5 psi under normal atmospheric pressure to break thru the stone. If you dont know your stones break pressure, you can test them by pulling them out of the tank, making sure they are absolutely clean, and hooking them up to co2. Then, using a bucket of water, submerse the stone; start @ 1psi and gradually increase pressure until the bubbles start to form - note the pressure, as this is now your working or "break" pressure.

[Supernaut]

The key is to carbonate as absolutely slow as possible and never allow for foam to break the surface tension of the beer. If you have any foam, you've gone too fast, and all youre doing is wasting gas.

I agree. As I dial in the sweet spot w.r.t. carbonation time, I keep going more slowly. We have no foam issues in the finished product but I don't want to lose character by foaming it over...

[OsgoodBrewing]

Great information here, thanks everyone.

If force carbonating with a sintered stone, using the methods above, about how long will it take to fully carbonate it? if it matters, let's say it's a 7 BBL bright tank at 40F.

Thanks!

[Supernaut]

Any where from 30 minutes to several hours. I haven't found a rhyme or reason for the variance yet. Note that I get the feed-and-bleed going and once the thing equilibrates at 15 PSI I check the carbonation level every 30 minutes until it is correct.

John