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Thread: Do I really need the bunging valve?

  1. #1
    Join Date
    Jan 2016
    very cold place

    Do I really need the bunging valve?

    Hi everyone!

    I'm trying to wrap my mind about the capping or bunging to full-ferment in my unitanks (without the brite). Currently I don't have any PRV\PVRV on my tanks, only spunding devices (very poor quality from China, 1-6 bar, impossible to set correctly). I already ordered PVRV from Glacier to be welded on top of my unitanks, and so, I wonder - do I really need a proper spunding\bunging apparatus?

    If I want to cap or bung, I could simply close the blow-off at some degrees before terminal and if somehow my yeast produce more CO2 than PRV can handle, it will open to blow this excess CO2 away.
    I will for sure never want to maintain more than 15 psi in my unitank because of yeast health and safety reasons (I can't naturally carbonate fully by capping, so why bother if I'm required to add force carbonation anyway?), and I can also add a pressure gauge instead of bunging device. Also, they are quite pricey!

    So, is there any reason for bunging device to be necessary in my setup?

    Thanks in advance for your assistance and replies!

  2. #2
    Join Date
    Aug 2010
    Enterprise, Oregon
    A PRVR is not a pressure-control valve. It is an safety feature. It should not be mounted permanently to your tank. Have a Tri-Clamp or similar flange welded to the tank, and mount the PRVR to that. The valve should be regularly cleaned and tested.

    A spunding valve, usually mounted to a down-tube of the tank, is used to maintain some pressure while fermenting. This valve also must be cleaned and tested regularly.

    You don't have to have a spunding valve, but you will be fermenting at ambient pressure, with a risk of back-flow and contamination.
    Timm Turrentine

    Terminal Gravity Brewing,
    Enterprise. Oregon.

  3. #3
    Join Date
    Feb 2013
    Oklahoma City, OK
    Quote Originally Posted by TGTimm View Post
    A PRVR is not a pressure-control valve. It is an safety feature.
    I just wanted to make sure this was stated again. So here it is.

  4. #4
    Join Date
    Feb 2014
    west coast
    as noted above- PRV/PVRV is not a pressure regulating device, its for safety only.


    doesnt mean you cant have two of them. the "SAFETY" PRV stays on top of the tank to avoid blowouts.

    the "PRESSURE" PRV can be attached to your blow off/CIP arm/dry hop port/etc to release any pressure above 15psi or whatever setting it has.

    now you're safe, and regulated to 15psi. basically you've got 15psi redundancy.

    if you want more of an actual spunding device that is adjustable and that isnt $500 then pick up a "back pressure regulating valve" and connect it up. i scored a few ControlAir 700BP units that are 0-30psi on ebay for like $30 bucks. if i recall they handle up to 50scf/m which according to the folks here is fine for 15bbl tanks. your mileage may vary.

  5. #5
    Join Date
    Oct 2013
    Cincinnati, OH
    Obviously you've heard at this point that the PVRV is a safety device and not a regulator. The rational is that the PVRV can be overwhelmed. If more co2 is being created than can be released, then your tank could fail. This is the reason that the PVRV's are usually sized at 2" instead of a "normal" 1.5".

    To answer your question a bit more directly, yes you can cap without spunding. At the pub we use a PVRV as well as a Burst/Rupture Disc (25 psi). We also cap at a low gravity as you have mentioned. Dry hop under pressure (sometimes) and that usually causes a fast spike in pressure, enough it could overcome the PVRV possibly, although that has never happened to me. You can carbonate your beers fully by capping, although it is a bit difficult to time. Yeast health will suffer some, but not to the point of creating unusable/undesirable yeast. We carbonate most all of our beers by capping. Occasionally we bump them up by head pressure in the FV, or rarely we add in through a carbstone in the BBT (barrel aged).

    If you use a bucket with sanitizer and a blow off hose, you are not fermenting at atmospheric pressure, and you will not have concern of back-flow/contamination. The sanitizer will be sucked up into the hose at negative pressure. You just have to make sure your bucket is large enough and contains enough sanitizer. The PVRV is more of a concern of back-flow/contamination in this case. I prefer spunding devices as they offer more flexibility and fine tuning, but they are by no means necessary.

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