Build a Spunding Valve!

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A Spunding Valve allows you to maintain a set pressure.  If pressure in the pressure vessel exceeds the set point, it is expelled.

Some homebrewing applications…

  1. Pressurized fermentation.  Ferment in a 5 or 10 gallon corny keg and use your Spunding Valve instead of an airlock.  This allows you to ferment at your desired pressure.
  2. Dry hop under pressure.  This allows you to dry hop earlier while reducing oxygenation.  Active yeast are more likely to metabolize oxygen that’s introduced during dry hopping during active fermentation.  Since CO2 is not exiting beer as vigorously under pressure, wanted compounds, flavors and aromas are more likely to stay in your beer under pressure.
  3. Naturally and accurately carbonate beer right in the keg.
  4. An airlock replacement.  Keep the valve wide open for non-pressurized fermentations.  Only do this if you have plenty of head space.  This wouldn’t make a great blow off tube.
  5. Keg to keg transfers.  Use the Spunding Valve to allow excess gas to exit the receiving keg as you transfer under pressure.  Helps you achieve a slow, controlled and pressurized transfer.
  6. Fix over-carbonated beers.  Use the same general process as for carbonation (skipping the addition of fermentable sugar).  Use a carbonation chart to determine proper pressure for the temperature the keg is at.  The Spunding Valve allows excess pressure to vent until the new carbonation level is achieved.  You can agitate the keg to fix carbonation more quickly.
  7. Test for keg leaks.  Pressurize your keg to serving pressure.  Put the Spunding Valve on (with the pressure set well above your serving PSI) and note the reading.  The gauge should remain steady.  If pressure drops, you know you have a keg leak.  It’s worth noting that this checks the entire keg including gas body o-ring.  That spot is hard to check and other way as it’s only in function when the gas QD is on.  When the gas QD is on… it’s difficult to spray and check for bubbles underneath the gas QD.  Thanks to Scott Janish for this tip!
  8. As an airlock for long term aging of beers.  Airlocks can run dry over time.  A Spunding Valve will not.  Thanks to Twitter Follower [Connect with HBF on Twitter] @BionicBrewing for this tip!

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This is a 2.5 gallon batch of beer that I fermented and naturally carbonated all in a 5 gallon keg.  This is a carbonated beer that I poured immediately after it was transferred into a serving keg.

About Carbonating with a Spunding Valve.  Carbonation directly in your keg allows you to naturally carbonate your beer (saving CO2 and $) while maintaining reasonably tight control on carbonation levels.  This could be done by adding priming sugar, capping fermentation prior to the completion of fermentation or more traditional krausening (adding wort back to the fermenter) methods.

Basic Steps for Carbonating in a Keg Using a Spunding Valve:

  • Prime the keg with your choice of priming sugar or wort (or start this process late in fermentation when some fermentable sugars remain)
  • Determine your desired pressure based on temperature and desired carbonation using a carbonation chart.  See: Balancing Your Draft System for a carbonation chart.
  • Pressurize the keg to just over your desired final pressure.
  • Attach the Spunding Valve
  • Dial down the pressure until you achieve your desired pressure
  • Wait.  As the remaining simple sugars are fermented, carbonation occurs and excess CO2 will be expelled from the spunding valve giving you just the right amount of carbonation.  I give it a couple days after reaching target pressure.  If you’re less sure how much fermentable sugar remained, I would suggest giving it a few days longer.
  • Chill your keg, allowing your beer to absorb head space CO2 and reach equilibrium.

On to the build:

Note: Product pages may display other size variations of the fittings used here.  If a particular size is out of stock, sometimes suppliers link to another size.  If you want to replicate this build, pay special attention to the fitting sizes that are used and double check to make sure you’re purchasing the correct size fittings.

Brew Hardware Options: Availability has been an issue on some of these fittings,  Brew Hardware has similar fittings, excluding the variable pressure relief valve.  See the end of this post for a list of alternate parts from Brew Hardware.  Note that these are similar, but not identical to what I used for the builds found in this post.

cln_img_9894This valve [Control Devices CR Series Brass Pressure Relief Valve, 0-100 psi Adjustable Pressure Range, 1/4″ Male NPT] is the heart of this Spunding Valve build.  It is essentially a manually adjustable pressure relief valve.  This one is adjustable from 0 to 100 PSI.  There is no homebrewing-related situation I’m aware of that would have you at 100 PSI.  Generally you’d be at or below 30 PSI.  As always, you’ll want to ensure that all components in your system (kegs, tubing, etc) are rated for your desired pressure.  Also, always read and follow manufacturer’s instructions and guidelines.

61uDeVq1w5L._SL1315_This build constitutes the second version of this valve for me.  My first build had a 30 PSI gauge.  That’s good for almost every situation.  With this update I wanted the ability to go to a little higher pressure if needed.  I used a Zenport DPG60 Gauge.  It reads 0 to 60 PSI.81uS3xkiWIL._SL1500_This stainless 1/4″ tee fitting connects the relief valve, pressure gauge and a final connection fitting together.cln_img_9897The tee fitting, gauge and valve together.  The gauge required valve sealant tape, the relief valve came with some sort of thread sealant.

The only thing that remains is choosing how the assembly will connect to the keg.  I’ll outline three options…

cln_img_0274Option 1: FFL (Female Flare) connection ready to connect to a pin or ball lock QD.  This version consists of Gas ball lock QD (it could just as well be a pin lock QD) – this fitting [1/4″ NPT Male x 1/4″ JIC Size] –  Stainless Tee – pressure gauge and this valve [Control Devices CR Series Brass Pressure Relief Valve, 0-100 psi Adjustable Pressure Range, 1/4″ Male NPT].  Valve Sealant tape goes on the first fitting and the pressure gauge.spunding valve buildOption 1 in actioncln_img_0276Option 2: MFL (Male Flare) connection ready to connect to a flare 1/4″ swivel nut.  This version consists of  this fitting [1/4″ NPT Male x 1/4″ JIC Male] –  Stainless Tee – pressure gauge and this valve [Control Devices CR Series Brass Pressure Relief Valve, 0-100 psi Adjustable Pressure Range, 1/4″ Male NPT].  Valve Sealant tape goes on the first fitting and the pressure gauge.  The 1/4″ MFL can connects to 1/4″ FFL female flare of your choice.cln_img_0281Option 2 with tubingcln_img_0282This version is nice if you’re tight on space.  You can coil it up on top of a keg or set it off to the side.

cln_img_0287Option 3: 1/4″ barb – Ready for whatever 1/4″ ID tubing you’d like to use.  This version consists of this fitting [1/4″ Hose Barb 1/4″ Male NPT] –  Stainless Tee – pressure gauge and this valve [Control Devices CR Series Brass Pressure Relief Valve, 0-100 psi Adjustable Pressure Range, 1/4″ Male NPT].  Valve Sealant tape goes on the first fitting and the pressure gauge.  You could also use a brass version [1/4″ Barb x 1/4″ NPT Male Pipe] of the barb fitting.

Some Tips:

  1. Check for leaks.  If you’re using a version that has a QD installed in some form or fashion, you can pressurize it on a keg and then take it off.  There will be a small drop when you take it off, but the pressure should remain steady after that.  If it’s going down, make sure everything is tight.  If you don’t have a QD… spray with Star San or soapy water until you are leak free.
  2. When setting desired pressure… start high and work your way down.  As the valve gets close to where it is going to eventually settle, it slows down the release of gas.  Working your way slowly down, helps you hit your desired pressure without passing it (going too low).

cln_img_9929Here I’m dialing in my desired pressure.  Also pictured: Thermapen Mk4 [First Looks].

Used in all options:

Option 1: Eaton Weatherhead 9100X4X4 Carbon Steel SAE 37 Degree (JIC) Flare-Twin Fitting, Swivel, Adapter, 1/4″ NPT Male x 1/4″ JIC Female

Option 2: Eaton Weatherhead 5217X4X4 Stainless Steel SAE 37 Degree (JIC) Flare-Twin Fitting, Adapter, 1/4″ NPT Male x 1/4″ JIC Male

Option 3: Parker 316 Stainless Steel Barb Connector To Male Pipe 1/4″ Hose Barb 1/4″ Male NPT

Option 3, Alternate: Anderson Metals 57001 Brass Hose Fitting, Adapter, 1/4″ Barb x 1/4″ NPT Male Pipe

Note:  Product pages may display other size variations of the fittings used here.  If a particular size is out of stock, sometimes suppliers link to another size.  If you want to replicate this build, pay special attention to the fitting sizes that are used and double check to make sure you’re purchasing the correct size fittings.

Brew Hardware Fittings – similar, but not identical to what I used for the builds found in this post.

Gas Disconnects:

Always make sure the parts you use are compatible and are rated for your intended application.  Contact manufacturers with questions about suitability or application.

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13 thoughts on “Build a Spunding Valve!

  1. Dave

    Nice write up. I just kegged my first beer. Is there any reason to use the female over the male flare fitting? or vice a versa.

    Reply
    1. admin Post author

      Hey Dave! – I suppose it comes down to how and where you’re going to use it. I like the “option 1” build the best. I like being able to attach this right on a keg with no tubing. It’s a neat, clean setup. Having said that I think the second option is good too. Practically speaking, they all do the same thing.

      Reply
  2. Perzell Brewing

    A possible solution for the flare fitting would be this fitting I know it is brass, but it is a check valve (to ensure you don’t get any stuff in your pressure relief valve) and it can fit directly on your quick disconnect.

    Reply
    1. Perzell Brewing

      After reading more about the check valve I mentioned, I don’t know if it would be a good buy for Spunding Valve because it won’t let air flow opposite direction. The SS fitting in this article is sold out. Brass alternatives:

      Option 1
      Option 2

      Reply
  3. Brandon

    I use a variation of option 2 on a conical for co2 transfer. If you use a cross instead of a tee you can throw a triclamp on the additional side or cap it off as needed for testing the guage (or fermenting in a keg). The MFL side is used with a gas line to transfer the beer in my case. That same line also can thread onto a beer gun, which is one advantage to using MFL’s. I didn’t think about it until reading this article, but I can cap that MFL off to use as a spund. The conical can’t hold the pressure like a keg can, but I can get a jump on it a save a couple days off the carbonation process by setting at 10psi or so. I’ll have to try it next time. Thank you.

    Reply
  4. Roy

    Great idea to have the Schraeder valve on there as well. You could use a regular air hand pump to move cleaner and santizer through kegs and save on CO2.

    Reply
  5. Scott

    I purchased the valve and have a question when using. The markings for the valve readings aren’t very accurate. The gauge reads 10 psi for example and the valve is set to almost 30 to keep the gauge stable at 10 psi. Is this your experience?

    Reply
    1. admin Post author

      No, that’s not my experience. The gauge reads a couple PSI off of what my regulator says, but I’m not sure if it’s wrong or if the regulator is wrong. In any case, they are close.

      Reply
  6. Will Fisher

    Hi, amazing article thank you. I really need this, one very important question tho.

    If I set my desired pressure to 20 psi, when the tank reaches more than 20psi it will open and release pressure. Does it close again at 20psi to maintain that desired pressure? Or does it just release all the pressure in the tank so you have to start building pressure again from zero?

    Reply
  7. Jake

    The link for the 1/4″ NPT male x 1/4″ JIC flare isn’t available on the link you provided

    Smallest size I saw was 1/2″…

    Know of any other sources to buy this piece? I would prefer to stick with the smaller footprint of “option 1”. Thanks!

    Reply
    1. admin Post author

      Hey Jake. Those links go to the general part page and then you select your size from there. I’ve tried to note that throughout the post. There have been availability problems for a while. I’m looking for alternate sources/parts but haven’t come up with anything yet.

      Reply

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