Monday 12 September 2022

Keg King - Spundy Spunding Valve - Hands on Review

When it comes to pressure fermenting, a critical piece of equipment required by brewers is a spunding valve. Since one of the byproducts of active fermenting yeast is carbon dioxide gas (CO2), when using a pressurised fermenter this CO2 gas builds up in the headspace of the fermenter. A spunding valve is used to regulate this pressure by setting/adjusting the valve so that when a certain pressure threshold is reached, the valve opens and vents the excess gas until it falls back below the set threshold. 

Keg King's Spundy Spunding Valve Box

Spunding valves are typically used in conjunction with Pressure Relief Valves (PRV's). PRV's work in a similar way, but are essentially a safety net to ensure that if there's a problem with your spunding valve, the maximum rated pressure for your fermentation vessel isn't exceeded which could potentially be catastropic for the fermenter (and lead to quite the messy cleanup).

The Spundy from Keg King, is a compact, plastic spunding valve with a couple of unique features that distinguish it from other spunding valves currently available on the market.

Spundy in it's box

Spundy is fully functional and ready to go straight out of the box with next to no assembly required. Unlike most other spunding valves that need to be attached to a separate gas ball lock disconnect, the Spundy has the gas disconnect integrated into it's plastic body, meaning it's easier to setup/install and has one less place for a troublesome leak to come from. 

We did have some difficulty with fitting our Spundy to the gas post of our new Apollo Titan fermenter with the locking collar not securing correctly. We worked around this quite easily though with a little lubricant on the ball lock post and by manually pressing the collar on the Spundy down to lock it onto the post after which we had trouble free operation.

Spundy fitted to our Apollo Titan fermenter

The size and profile of the Spundy is low - coming in at only 4.5cm tall, and when fitted to a gas ball lock post it will only add 2.5cm to the total height/clearance above the top of the post. This makes it an ideal option for those with limited space or height limited fermentation chambers/fridges.

Spundy's integrated gauge is surprisingly accurate

There is an integrated pressure gauge - reading up to 30 psi or 2 bar of pressure. When testing it's accuracy against our CO2 regulator gauge the spundy was reasonably accurate, consistently reading 1-2 psi lower when tested at 5, 10, 15, 20 and 25 psi. Small format gauges such as this one are generally less accurate than larger ones and in an application like a spunding valve it's a worthwhile compromise, since pinpoint accuracy is not really required. Having the gauge integrated is a real bonus though, negating the need for T-pieces and other joiners to be fitted, once again reducing the likelihood of gas leak sources being introduced.

One draw back of the integrated gauge design however, is that the gauge display can't be tilted/adjusted so your eyes need to be in line with the gauge in order to read it accurately - for us this required us crouching down in order to read the current pressure on the gauge when fitted to our Apollo Titan in the fermentation fridge.

Where the Spundy really separates itself from other spunding valves is with it's ability to 'preset' the working pressure by fitting a PRV into it. Out of the box it comes fitted with a spring and poppet, with the working pressure being adjusted by tightening or loosening the black knob/cap which tightens/increases the tension on the spring and poppet. This allows really precise adjustment of the set pressure which is nice, but arguably not entirely necessary when fermenting under pressure.

Spundy - disassembled in preparation for PRV install

Now brewers have the option to simply unscrew this black knob/cap, remove the spring and poppet and screw in either a blue (10 psi) or purple (15 psi) PRV in it's place. These are the same PRV's that are compatible with Keg King's range of pressure capable fermenters (Apollo, Fermenter King Jr, Chubby), and the colour coded pressure ratings make them easy to identify. The process of swapping over takes less than a minute, and means you have an accurate and predefined set pressure that the Spundy will work at. No more messing around with finicky adjustments and wasting precious CO2 gas to get your required set pressure, which for us was a really ingenious idea.

Be careful not to misplace the small spring and poppet if you do decide to fit a PRV though. There are some cases where the finite adjustment of a spunding valve may be required or preferred, such as to slowly bleed out pressure to avoid a 'krausen volcano' before opening your pressure fermenter, or for regulating pressure during a pressure transfer to a keg - more on that later. We found Spundy's box to be a good storage option for any parts that aren't currently fitted and in use (so don't throw it away!)

Spundy with the blue (10psi) PRV installed

The gauge can be unscrewed as well, meaning the Spundy can be fully disassembled for cleaning in the event of a particularly enthusiastic krausen breaching the headspace of your fermenter and seeking freedom via the gas lock post the Spundy is connected to.

As with any pressure fermenting and spunding valve setup, brewers have the ability to use the CO2 gas created by fermentation to purge the headspace of an empty keg with this CO2 gas by fitting a disconnect and beer/gas line from the gas post of their fermenter to the liquid post of their keg. The Spundy can then be fitted to the gas post of the keg to steadily release excess pressure from the keg. The same principle applies with pressure transfers from fermenters to kegs, and we found the ability to manually adjust the venting pressure (by fitting the original poppet, spring and black adjustment cap) worked really well during our trial pressure transfer.

Keg King have the Spundy available in a number of kits.

The first kit, named the Spundy Supreme has the Spundy, blue and purple PRV's and the required disconnects and beer/gas line for CO2 keg purging for AU$29.00.

There is also the Spundy Plus which has the Spundy and the blue and purple PRV's included for AU$20.95.

Finally, you can just buy the Spundy on it's own for AU$15.95.

If you're in the market for a new or replacement spunding valve, the Spundy from Keg King is well worth considering. We'd recommend the Spundy Plus kit as we found simply screwing in one of the included PRV's to automatically preset the working pressure to be a great inclusion.

With the integration of a pressure gauge and gas disconnect mechanism into the low profile body, it's ready to go straight out of the box with no additional hardware required. It performed well in our tests, reliably controlling the internal pressure of our fermenter during active fermentation.

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