Pressure Relief valve on Unitank

[SideLot]

Alright folks, prepare for what is probably a dumb question or two.

I bought a 3bbl unitank, like the one pictured below. At the top is the manway, and pressure relief valve. I was told I needed to to set the valve to handle the proper pressure. How do I do that?

Dumb question number two. Am I able to take that valve off (tri-clamp) and run a blow off tube from there? Or des the valve act as an airlock?

I bought this used and it appears the company that made it (Blackstone Ventures) is no longer in business because their website has nothing but a logo on it.

Any info and insults are appreciated. Thanks

[Rooh]

You can remove prv from tank and adapt a t.c. fitting to a regulated air or CO2 supply at desired relief pressure, tighten or loosen big nut inside until you get desired results.

Rich DeLano
rich@thebrewinglair.com

[Todd Hicks]

... and no, the PRV can not be used as an airlock. It is for safety only. Most brewery cellar tanks are only operationally rated at 15 psi, even though they are tested at up to 30.

Remove the PRV and use a blowoff hose dropped down into a bucket of clean water. Your size may be different but, most PRV are 2" TC, so get a 2" TC to 1 1/2" TC elbow, two 1 1/5" TC to 1" hose barb, and a length of 1" PVC hot tub hose. I like to keep a TC barb on both sides of the blow off hose for CIP use.

After primary subsides, remove blowoff hose and fittings, clean up any spooge, and install the PRV with a clean gasket.

You will also want a valve or cap on the end of the CIP pipe. If you plan on finishing the fermentation under pressure, you will need to add a spund valve, some sort of CO2 inlet valve, probably a T, pressure gauge, and other apparatus to maintain conditioning pressure and not blow yourself to smithereens.

Be careful, it sounds like you need some sage advice.

[lhall]

Todd,

I hate to disagree but I don't think you should take the PRV off the tank. Venting the tank through the CIP down-pipe should work fine.

You can check the blow-off pressure of the PRV by hooking it up to a CO2 source, putting it in a bucket of water, and seeing what pressure bubbles start escaping. Not all types of PRVs are made to be adjusted.

[TheCarolinian]

I hate to disagree but I don't think you should take the PRV off the tank. Venting the tank through the CIP down-pipe should work fine.

I agree. This is how I have seen it done in most operations.

[soia1138]

Todd,

I hate to disagree but I don't think you should take the PRV off the tank. Venting the tank through the CIP down-pipe should work fine.

You can check the blow-off pressure of the PRV by hooking it up to a CO2 source, putting it in a bucket of water, and seeing what pressure bubbles start escaping. Not all types of PRVs are made to be adjusted.

I'm with Todd on this one. Removing the PRV during fermentation and turning that port into the blow-off port does a couple of things. First, it saves the PRV from getting all gunked up during a vigorous ferment and causing potential failure down the road if not cleaned and maintained well. Second, most unitanks now come with a separate blow off arm in addition to the CIP arm. Your sprayball could become clogged as well during fermentation and if using that as your blow off source then there is no unobstructed egress for all that yeast and protein. While that PRV is off would be a good time to make sure it is clean and set properly before installing it back on the cleaned port. My two cents anyway.

[TGTimm]

Removing the PRV during primary fermentation totally defeats the purpose of having a PRV! When else are you going to be building pressure in the vessel?

I'd add a T below the PRV and run a drop-tube from that for your blow-off. I would never, ever, operate a fermenter with the PRV removed. I've already seen what happens when the blow-off from a glass carboy gets blocked, and the stopper is tighter than the pressure tolerance of the glass.

While you have the PRV off, make sure it's a Pressure/Vacuum Relief Valve. If it isn't you risk collapsing a fermenter--less fatal than blowing one, but it destroys the vessel.

[Todd Hicks]

For safety sake, a T under the PRV would give another port for a blow off hose is a good idea. Also, if you have a hop port, I would put an adapter there and attach PRV.

And as said, newer fermenters usually have several ports on top these days. PRV, blowoff, CIP, hop, sensor.

For tall tanks, I have connected blowoff tube to CIP drop and left PRV up top. Less hose to clean. Each tank's blowoff hose became a CIP hose to the pump.

Configurations vary. Good suggestions.

[BrewinLou]

Put me in the group of "never use a tank without a pressure vacuum relief valve". Fermentation, carbonation, and hot rinse are the most important times to have the prv installed. A brewery I know removed theirs and ruptured tanks in three separate incidents. Once the blowoff clogged with dry hops, once a cellarman walked away and forgot he had the CO2 on, it happens, don't be that brewer. I prefer to have 2 prvs on Ts at the bottom of the blowoff arm followed by a butterfly valve. They are easily accessible for cleaning, and you will not implode or explode your tank. We check ours for set point monthly and fully disassemble them once a quarter.

[soia1138]

So, one question here. How is it ok to put a T below the PRV for blow off. If that T/blow off drop clogs then doesn't that render the PRV (which is now above the clog) useless?

Tank > Clogged T > PRV ??

[TGTimm]

Nothing in this world is perfect, but the risk of a clog in a 1 1/2" (or 2") dia, 4" long straight run of a T is somewhat less than that of a clog in a 10' long blow-off hose of whatever diameter.

In the example I gave earlier, where we managed to frag a glass carboy, the blow-off line had a box full of supplies placed on it.

Most of our PVRVs mount to the top fitting of the tank.

[BrewinLou]

I have 30 bbl fvs and 60 bbl fvs. The newer ones have all come in with 1.5" CIP drop tubes, and 2" blowoff drop tubes, as well as a 2" port on top for the PVRV. I cap the 2" port and add a 2" T to the bottom of the blowoff arm where I place the PVRV for easy access and easy monitoring. I use the CIP arm for my blowoff bucket air lock and the blowoff 2" tube as a backup. All of the FVs here have 2" openings on top for PVRVs.

[wailingguitar]

There is an easy way to avoid having to worry about anything coming up through your blow off, gumming up the PRV, and making a general mess; Patcote from BIRKO ( I suspect there are similar products out there as well). I started using it for fermenter anti-foam after several batches of porter foamed out and made a huge mess. 2oz into the whirlpool (10bbl kettle) keeps the foam under control in the tank, and leaves the tank a bit easier to clean. Have had zero issues with head retention, etc in the finished product. I almost never see any soil on the tank domes and can't remember the last time I had anything come out the blow off.