Using a spunding valve will make better beer. Really, how can one make such a bold claim? While there are lots of product claims to make better beer, this one will definitely improve your beer, the claim of making it better will depend on how you use it. The primary use of a spunding valve is to ferment beer under pressure. While this is a good use homebrewers don’t gain much from it. A better use is to reduce oxygen uptake in your beer during transfers which will improve shelf life and hold in aromas from dry hopping. Oxygen can stale a beer and eliminate all if not most of the aroma. Of all the various uses for spunding valves here are some of the better ones.
Ferment under pressure
The ability to mimic large scale brewing when the size of the fermentor and weight of wort causes pressures of 1.05 bars to 1.8 bars of top pressure or 15.22896 psi to 26.1068 psi. When fermenting under these pressures you can benefit from being able to ferment at warmer temperatures without increasing off flavors which will allow you to ferment at faster rates. The overall yeast ester and fusel production will be reduced giving you a cleaner final beer in both flavor and aroma. A less vigorous fermentation, the pressure reduces krausen production so less headspace is necessary. Any aroma compounds will remain in the beer and are not blown off through an airlock and lifted with the formation of krausen. C02 generated from the fermentation can be used to naturally carbonate the finished beer.
Dry hop with less oxygen uptake
Dry Hopping add lots of great aromatics to beer. I love a great IPA with a thick foam head that carries all of that aroma right to my nose. As homebrewers we don’t have the ability to keep our beers fresh longer without going stale and losing all of those great aromatics, or do we? In production scale brewing all cans, bottles and kegs are purged with C02 to remove most oxygen from the serving vessel. (I say most because all commercial packaged C02 contains a percentage of air which will include some oxygen.) So how do we as homebrewers preserve our aromatics in beer for longer? With a spunding valve.
Using a spunding valve during secondary fermentation can allow us to keep out the oxygen. Better yet is that by using the remaining yeast in the beer we can eliminate all oxygen during the last phase of the fermentation. When producing alcohol yeast consumes any oxygen present in the wort and in the headspace of the fermenter. During this process the yeast produces C02. By using the yeasts natural ability to eat the oxygen and make C02 we can eliminate all oxygen during the crucial dry hopping stage of making great beer. By setting the Spunding valve on your kegged and dry hopped beer you can release any excess pressure during the final stage of fermentation and even carbonate your beer naturally in the keg if so desired.
Naturally carbonating beer in the keg
It’s helpful to know when to begin the secondary stage of fermentation so the yeast will still be able to produce C02. By performing a Fast Ferment Test we will have the ability to know what the expected final gravity of the beer will be before it’s finished. (see Fast Ferment Test below) Most american styles require about 2.2–3.0 volumes of C02 carbonation in the finished beer. In order to calculate this you need to know the amount of gravity points or degree Plato that unfermented wort produces. Since 0.5% CO2 is about 2.5 vol, you need 0.4°P of attenuation (about 1.6 gravity points) for every volume of CO2 you want to add. So once you decide on how much carbonation you want in your finished beer you can simply begin the secondary fermentation by calculating the points needed to create the desired volumes of C02 from your Final gravity. Here is a bit on how to perform a Fast Ferment Test to obtain your final gravity.
Fast Ferment Test
To perform this test you need a sample of wort and yeast. The amount of wort should be enough to perform a hydrometer reading later (6 to 8 oz (120 to 200 ml)). The amount of yeast should result in a pitching rate for that sample that is well above the pitching you would use in a beer (5-10x).
- Pull a sample of wort before pitching yeast. (Use the same sample to measure OG)
- Pitch most of the yeast/wort mixture and leave a little in the flask or bottle
- Add the remaining yeast to the sample. (be sure there will be enough to measure the beer with a hydrometer after it ferments)
Cap the bottle or flask with tin foil or an airlock. Put it on a stir plate or shake it occasionally to keep the yeast in suspension. Place the test at a warm place ( 20C / 70F and above, warmer for ale yeasts). It should take 1 or 2 days for the fermentation to be over and it’s probably best to give it another 2 days until you see the sample lies completely flat and no CO2 escapes when you shake it.
Now you can measure the extract (gravity) of the sample beer. This will give you the lower limit of the final extract (final gravity) that you can expect for this wort.
Transfer to serving keg with C02
The spunding valve allows you to add a set amount of back pressure to the keg to ensure a slow constant transfer from fermenter to keg or from keg to keg. Transferring your beer under C02 prevents any oxidation that may be picked up during this process. Oxidation can lead to premature stale beer, loss of hop aromas and other desired aromatics in the beer. Setting the pressure low around 5-10 psi will ensure you have enough pressure to transfer the beer without over pressuring the fermentor. (Please read caution note below)
NOTE: If transferring from a plastic bucket or glass carboy your C02 pressure coming from the C02 tank should be set very low to prevent breaking the glass carboy or popping the lid off of your fermenter. Please be very careful as to not get hurt. It does not take a lot of pressure to transfer the beer. You should also position the fermentor higher than the keg you are transferring into to benefit from a natural syphon vs the pressure of C02.
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