A Spunding Valve allows you to maintain a set pressure. If pressure in the vessel exceeds the set point, it is expelled. It generally consists of an adjustable PRV valve, a tee, a gauge and a way to connect to your keg.

Homebrewing Applications of a Spunding Valve

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. 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. Naturally and accurately carbonate beer right in the keg. 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. 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. Fix over-carbonated beers. 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. The digital build, see below, is especially helpful for this task, The digital gauge reads with .1 PSI resolution making pressure changes easy to spot. 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! As an airlock for long term aging of beers. Airlocks can run dry over time. A Spunding Valve will not.



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.

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.

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. See: Balancing Your Draft System for a carbonation chart. 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.

Oxygen Free Cold Crash and Transfer Using a Spunding Valve

Check out my Step by Step Process for Cold Crashing & Oxygen Free Transfer with the help of a Spunding Valve

Use CO2 Produced by Fermentation to Purge Serving Kegs, Carboys & Fermenters

This technique requires a BlowTie Spunding Valve. Since the the BlowTie has a defined output port, you can use it to capture CO2 produced by fermentation. The “out” side of the BlowTie is a DuoTight connection, just like the “in” side. Use compatible EVABarrier tubing and fittings and you can route outgoing CO2 wherever you’d like. The primary application I can think of for using this is to purge kegs, carboys and fermenters. The pictured setup shows a 10 gallon keg converted to a fermenter. The “out” side of the BlowTie is connected to the liquid out side of an empty keg. That allows incoming CO2 to purge the keg from bottom to top. The lid PRV valve for the receiving keg is open to allow pressure to vent. Of course you could tee the “out” side and flush multiple kegs or vessels using the CO2 produced by a single fermenter.

Related: Hands on Review: Kegland DuoTight Fittings & EVABarrier Tubing!

Building A Spunding Valve

Important 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. All thread sizes for this build, both NPT and flare, are 1/4″. 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.

Because availability of fittings can be an issue, when available, I’ve linked to multiple options and vendors for each build type.

This 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. A stainless options is now available! Adjustable Stainless Gas Pressure Relief – 1/4 in. MPT via MoreBeer – note that this is a stock photo

For years the only PRV option we have used is the Control Devices Brass PRV featured in the previous photo. We’ve also thoroughly reviewed Kegland’s BlowTie Assembly . That is a Kegland DuoTight/EVABarrier/BlowTie solution.

You can also use the BlowTie Diaphragm Spunding Valve as part of a DIY Build. The key to connecting the BlowTie to this build (and probably most DIY builds) is using a Duotight 8mm ¼” NPT Adapter. That connects to a 1/4″ NPT tee. From there you add a small piece of 8 mm EVABarrier Tubing and the BlowTie valve. My first Spunding Valve build featured 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. This stainless 1/4″ tee fitting connects the relief valve, pressure gauge and a final connection fitting together. Practically speaking any properly rated 1/4″ NPT threaded tee fitting should work. The 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 your serving or fermenting keg. These are grouped into general connection styles. Some styles have similar fittings that accomplish the same thing. Additional fitting options for each build can be found in the complete parts list toward the end of this post. When I’ve tried a fitting, I’ve included a photo.

Style 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] (* sizing note) – 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.

Style 1 in action

Style 1 Variation: Using a brass fitting – LASCO 17-6783 1/4-Inch Female Flare by 1/4-Inch Male Pipe Thread Brass Adapter (* sizing note)

Style 2 [as of the most recent update to this post, this fitting is not available in the size I used for this build, pay close attention to the note about thread size that follows]: 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 ] – linking to incorrect size as of this update (* sizing note) – 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. Style 2 with tubing This 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.

Style 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] 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.

Style 3 Variation: Using a brass barb – Anderson Metals 57001 Brass Hose Fitting, Adapter, 1/4″ Barb x 1/4″ NPT Male Pipe (* sizing note)

Style 3 Variation: Using a brass barb – Anderson Metals 57001 Brass Hose Fitting, Adapter, 1/4″ Barb x 1/4″ NPT Male Pipe (* sizing note) and brass tee – Anderson Metals 56101 Brass Pipe Fitting, Barstock Tee, 1/4″ x 1/4″ x 1/4″ NPT Female Pipe – thank you to /u/workaccount32 on reddit for this photo

Style 4 : This build uses a cross fitting instead of tee fitting. The additional leg has a ball valve [1/4″ Stainless Steel (316) Mini Ball Valve – FxM NPT] on it. My thinking on this was to give you the option to use one Spunding Valve on multiple kegs. This could be for any of the functions mentioned above. Pick the connectors you want for your intended purpose. One idea – ferment one beer under pressure and use that pressure to force carbonate another beer to save CO2.

A Digital Spunding Valve!

This version utilizes Primefit’s Part CR1401G. Most of our builds consist of a PRV Valve + tee + gauge + connection option. Generally four parts in total. The CR1401G replaces two parts, both the tee and gauge. See: Spunding Valve Build: Using Primefit CR1401G Replacement Air Regulator for more details

Making a digital Spunding Valve is as simple as using a digital gauge.

I tried a couple different digital gauges and settled on

– pictured in the assembly above. The other gauge I tried was much more expensive and didn’t really work well. It drifted wildly. This was a reasonable price and has given me accurate and consistent readings. This photo shows two gauges hooked up to the same keg – agreeing on PSI.

The really nice thing about this digital gauge is the .1 PSI resolution. That’s really handy if you’re using the gauge to try and find leaks. It allows you to see pressure changes more quickly.

My gauge came with this user manual/specifications sheet – front | back. One quick tip… the threads aren’t super long. The first time I put this digital Spunding Valve together, I noticed the pressure dropping, again… the .1 PSI resolution is handy for spotting just this issue! Anyway, I didn’t have the gauge quite tight enough and it was showing a slow leak. Easy fix, I took the gauge off, put a couple extra wraps of teflon tape around it and tightened it a little more. Whammo!

Digital Low Pressure Gauge with 1/4” NPT Bottom Connector and Rubber Protector by Uharbour, 0-60 psi, Accuracy 1%, Resolution 0.1psi

Spunding Valve Tips

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. 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).

Here I’m dialing in my desired pressure. Also pictured: Thermapen Mk4 [Review].

Spunding Build Parts List

As outlined in the different build types detailed in this post, a Spunding Valve assembly can be built in a number of different ways based on your desired application, budget and parts availability. This parts list is broken up into sections by component type.

Adjustable PRV Valves:

Pressure Gauges:

Tee Fittings:

Tee+Gauge Option:

PTFE Tape:

Keg Fitting Options: – How do you want your Spunding Valve to connect to kegs or fermenter? I’ve tried many of these fittings myself. For fittings I’ve tried, I include a link to a photo

Style 1 – Female Flare, Connect to Pin or Ball Lock QD (* sizing note)

Style 2 – Male, Flare, Connect to tubing via Swivel Fittings (* sizing note)

Style 3 – 1/4″ Barb, use tubing clamp to connect directly to tubing (* sizing note)

Are you from Canada? See our post with parts that are generally available in Canada – Canada: Build a Spunding Valve! – How and Why

Cheapest Option:

Generally speaking, the brass variations of these fittings are probably going to be the most economical route to go. This is a general statement and may not always be the case. Check product pages for current prices and availability.

Thank you to /u/workaccount32 on reddit for this photo

Brass Combo – This package gets you two brass tees and two brass barbs: WYNNsky Metals Brass Pipe Fitting Barstock Tee 2 PCS 1/4″ x 1/4″ x 1/4″ NPT Female Pipe 2 PCS 1/4″ NPT X 1/4″ Hose ID Brass Hose Barb Fittings – this combo would replace the two Anderson Metals Fittings above

Search: As mentioned previously, availability of fittings in the proper sizes can be an issue. This has proven especially true for the keg fitting options piece. The two thread types for that piece in this build are 1/4″ npt and 1/4″ SAE JIC. This Amazon Search may be helpful in finding compatible fittings for the build you’d like to complete. Note: that search may very well return fittings that are not helpful for this project. Pay attention to thread size, material and fitting gender. If you find a great fitting that isn’t listed here, Submit a Tip and let us know about it.

Gas Keg Disconnects:

Ball Lock – search Amazon

Pin Lock – search Amazon

Ready Made Spunding Valves

Some ready made options are now available. Here’s a rundown of off-the-shelf options.

New Kegland BlowTie v2!

Pictured: BlowTie Spunding Valve Assembly via my Hands on Review

BlowTie v2 has been released. The major improvement is… a built in gauge. Look for an update to this review in the future. General concepts should remain the same. I recommend purchasing the newer v2.

Related Resources!

Homebrew Finds is Spunding Central! Check our related resources and more detailed builds

Important Note About Fitting Sizes and Availability

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. All thread sizes for this build, both NPT and flare, are 1/4″. 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.

Make sure the components you use are compatible and rated for your intended application. Contact manufacturer with questions about suitability or a specific application. Always read and follow manufacturer directions.





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