Pressure Barrels - More than you wanted to know!

[Hazelwood Brewery]

Introduction

I use quite a few bottom-tap King Keg pressure barrels and I have very few problems with them. From discussions on the forum though it’s clear that many people do struggle with pressure barrels so I thought I might put together a few thoughts you might find useful. Although I will be talking about bottom-tap King Kegs in the main there’s quite a lot of information in here that will be useful for other pressure barrels. The tips on the S30 pressure release valve and about taps may still apply regardless of which barrel you use. I hope something in here solves your problem and if it doesn’t, update this thread when you find a solution for others to learn from. Cheers!

 

[Hazelwood Brewery]

Why a pressure barrel?

So when you can bottle beer, why bother with pressure barrels at all? My view - bottles are a real headache with all that cleaning, sterilising, filling, priming, capping, labeling, the risk of bottle bombs from over-carbonation or flat beer from under-carbonation. What you have to do 40 times over with bottles, you do just once with a keg. When it comes to carbonation, all the beers in the picture below came straight out of a pressure barrel beautifully carbonated and conditioned. You can of course get the same results with other systems but for me, pressure barrels are a good way to get great results without the hassle of bottling and without the complexity and expense of full-on cornelius (“corny”) keg setups with kegs, gas bottles, regulators, and all the plumbing – which is all a bit daunting in the beginning when you don’t even know what things are called let alone how they’re assembled and used.

 

[Hazelwood Brewery]

Choosing a pressure barrel

If you do decide to try a pressure barrel, there’s a range of sizes and designs available and you’ll soon be wondering which is the best and how you even choose. Other than size and price there are several factors you might consider but two you might not think about immediately are the quality of the barrel and the size of the cap on the top. If you have the choice, quality is important because the lower quality products are more likely to be thin-walled and will split or develop pin-holes more readily than better quality, thicker-walled barrels. The cap size makes cleaning easier or harder – a four-inch opening is easier to get your arm in than a two-inch opening. I chose my King Kegs because they are better quality and have a four-inch opening.

 

[Hazelwood Brewery]

So you’ve chosen a King Keg too?

If you’ve decided on a King Keg, your next decision might be whether to go for the top-tap or the bottom-tap. The advantages of the top-tap are that you can fit a glass under the tap easily and you should be able to pour a clear pint sooner than with the bottom-tap because beer clears from the top down. The down side of this though is that you need a floating mechanism to always draw the beer from the surface and you need pressure to push the beer out. The bottom-tap keg is more simple with no floating mechanism to worry about (isn’t there an expression about keeping things simple). The advantage of beer being drawn off more quickly might also not be so much of an advantage given that beer still needs time to condition and this takes longer than the time to clear. I chose the bottom-tap version because there is less to go wrong and my kegs all sit on shelves with the tap hanging over the edge so getting a glass under the tap is no issue for me.

When you order your King Keg there are a few items that you should order at the same time to make your life easier and you may even have one or two of them around the house already. You will need a cap spanner, some small cable-ties, a roll of PTFE tape, and you may need some Vaseline (read below about taps). You should also buy a new set of seals for the S.30 valve (see below about valves) and if your King Keg comes with the type of tap you see on the top-tap keg, you might want to buy a replacement tap of the type you can see on the bottom-tap keg (again, read below about taps).

You will also need some CO2 bulbs or a CO2 bottle depending on whether you use the pin-valve or not (see section on valves below).

When it arrives you get a keg, a cap with a rubber seal, a pressure-release valve (the S30 valve) that will fit into the cap, and a tap. Assembling this stuff is easy enough but making sure you have no leaks of beer or gas? That’s entirely different.

After checking for any obvious manufacturing issues and transportation damage, wash the keg and cap in clean soapy water and give them a good rinse, ready for assembly and testing.

 

[Hazelwood Brewery]

The tap

You would think it would be a simple case of “fit the tap” but I’m afraid you’d be wrong. First, have you got the right tap? If you took my advice earlier and bought one of the black taps shown above that’s great, you’re going to have less of an issue with a drippy tap.

First though you need to know what typically goes wrong with taps and how you avoid the issue – this applies with all taps. The most distressing issue is where the tap appears fine, even when you fill the keg with beer, but as the beer carbonates and pressure builds (and almost always in the middle of the night) the seal between the tap and the keg fails. The result of course is that you have a leak and in the worst case all your beer escapes the keg and floods your floor or worse, escapes under the floor boards.

The problem here is that the tap needs to be tightened enough so the rubber seal between the tap body and the keg makes a good seal, even under pressure. The trouble is that in trying to tighten the nut on the back of the tap you might well over-tighten it and damage the tap threads, or in fear of damaging the threads you might not tighten it enough.

The fix is actually just lots of PTFE tape which helps to better mesh the threads and has the added benefit of also sealing the threads just as you do in household plumbing.

Take your tap and remove (if fitted) the rubber washer that will seal the joint between the tap and the keg. Wrap PTFE tape around the threads until the threads themselves almost disappear, I think I wrapped this one twenty times. Then replace the rubber washer taking care not to disturb the PTFE tape too much and fit the tap nice and tight. If while tightening the nut it jumps the threads you haven’t used enough PTFE tape – add more and be generous because you can’t do this many times without damaging the threads on the tap beyond serviceable use. You’ll know it’s good enough when its impossible the push your thumb nail between the tap body and the rubber seal. The rubber seal is on the outside of the keg isn’t it? The last picture in this sequence is a view from inside the keg.

If you didn’t take my earlier advice to replace the type of tap pictured below, no problem (mostly). This tap needs the same treatment as the black tap as far as fitting is concerned with the PTFE tape but you have another problem – dripping from the tap. To minimise this (you will probably not stop it altogether), you need lots of Vaseline. Vaseline is food-safe in case you’re wondering.



Pull out the tap from the tap body (it just pulls out), smear lots of Vaseline over the tap, reinsert it into the body, and wipe off the excess. This will mean that the beer doesn’t drip to start with but after repeated use of the tap, it will start to drip again.

 

[Hazelwood Brewery]

The S30 valve

A failed tap is heartbreaking but thankfully doesn’t happen too often. A leaky valve on the other hand is a common issue for people. The S30 valve has two basic forms; there’s a brass version and a stainless steel version. The brass version is fitted by inserting it through the hole in the cap from above and the nut is fitted below. The stainless version is fitted by inserting it into the cap from below and the nut is fitted from above (along with a stainless steel collar). In both cases the rubber washer sits against the flange on the valve and is pressed against the cap. This seal is one source of trouble, almost always because people over-tighten the joint thinking this will produce a better seal or mistakenly thinking a leak is coming from this seal. The pictures below show the valves, shows the seals, and shows a cross section diagram of the brass valve.

The operation of the valve is quite simple but it helps to understand how it works in order to diagnose and fix problems with it. In both the brass and stainless versions the basic aim is the same: they allow excess pressure to be released from the keg so as to not exceed a safe level, around 15psi. As a secondary function, the S30 valve allows gas to be injected into the keg and not escape (other than when this raises the pressure above safe limits and then the pressure-release feature is activated).

The pressure release mechanism involves a channel drilled up through the base of the valve and out of the body above the cap. You can see the holes in the picture below and the arrows indicating the gas flow. In the normal course of events the exit hole is sealed by the brown rubber band (lifted below so you can see the hole) but as pressure increases the gas will eventually push past the rubber band and emit a hissing or squealing sound for as long as gas is escaping, gas will stop escaping once the pressure has dropped to a safe level. During secondary fermentation it might be perfectly normal to hear this valve hiss from time to time as pressure builds.

You may on occasion need to inject CO2 if you draw off the beer faster than more CO2 can be produced to maintain pressure, or you may have a fault and need to replenish CO2, or you may just prefer to inject CO2 rather than wait for secondary carbonation. Whatever the reason, you inject CO2 into the top of the valve and it travel down a hole to the pin at the base of the valve (inside the keg) and again past a rubber seal. The rubber seal is there of course to prevent the gas just travelling back out the same way in reverse.

The valve uses something like a sodastream CO2 bottle as it’s source of CO2. To inject CO2 you screw the bottle onto the valve for a moment, injecting the gas, and you then unscrew it. The disadvantage of these bottles perhaps is that they cannot be sent full of gas through the post so you will need a local gas distributor (often a DIY centre) to fill these for you.

If having to visit a gas distributor isn’t convenient for you, you can use smaller 8g gas bulbs that can be sent through the post but your valve will need a “pin-valve conversion” like the one shown below from brewstore. Often when you buy an S30 valve, or a keg that comes with a S30 valve, you will have a choice of which valve you want – the S30 or the “pin-valve” – this is the same S30 valve but with the pin-valve conversion already fitted. If you buy the kit all you need to is drop the pin-valve (with the spikey bit pointing out) into the hole in the top of the S30 and fit the o-ring into the groove to retain it and provide a seal round the neck of the gas bulb. If when you inject a gas bulb, CO2 escapes rather than going into the keg, you may have stretched or damaged this seal and need to replace it.

Valve Conversion Pack (S30 to Pin)

The image to the left shows the pin-valve conversion completed. To screw the bulb down onto the pin-valve you will also need to buy a CO2 bulb adapter, the black plastic device to the right. The gas bulb is loaded into the adapter and the adapter is screwed down onto the valve so the pin in the valve pierces the bulb seal and releases the gas into the keg. Naturally, once the bulb has been pierced all the gas will be released so these can only be used once.

 

[Hazelwood Brewery]

Valve related issues

The most common problem people experience is a loss of pressure. Assuming the cap is well sealed against the keg (we’ll come back to that), the three ways in which gas can escape via the S30 valve are through the gas-in path, the gas-out path, or where the valve goes through the cap.

The valve seal is achieved using a thick rubber washer that gets pinched between a flange on the valve and the cap the valve is fitted to. This seal rarely leaks and when it does, it’s usually because the joint has been over tightened and the rubber washer has been distorted. In the left-hand image below you’ll see how the rubber seal is squeezed out from under the flange and is distorted through over-tightening. In the image on the right the seal is more circular and will give a better seal (we’ll return to the cable-tie). Before fitting the valve make sure there are no burrs, no raised edges, and no imperfections around the hole in the cap (also be sure not to create deep scratches or scores where the cap will come into contact with the seal) and make sure the rubber seal itself is in good condition. When fitting the valve tighten the nut as far as you can with your fingers and then use a spanner to tighten the nut another ½ to ¾ of a turn. If you over tighten the seal don’t just back off a little, undo the nut until the rubber washer moves freely and returns fully to it’s rounded shape and start again.

I noted above the gas-injection mechanism. You inject CO2 at the top and it enters the keg through the bottom of the valve, emerging from the hole in the side of the pin with the pink rubber tube over it. The rubber tube allows the gas in but stops it escaping again.

The problem people sometimes get is that when injecting CO2 the pressure of the gas not only squeezes past the pink rubber but blows the pink rubber seal clean off its pin and into your beer. If this happens you now have an open route for gas to flow back out the same way it came in AND you now can’t inject any gas until you’ve fixed the problem and your rubber seal is in your beer! This latter point isn’t so much of an issue if you have a spare rubber seal but it would be better to avoid the whole sorry story. A cable-tie tightened around the pink rubber (but not blocking the gas-in hole) is the solution. See in the third image along the hole is still clearly visible throug the pink rubber tube.

One important point though, the rubber seal also must not be pushed hard against the valve flange causing it to buckle because this also causes gas leaks so if required trim a tiny sliver from the rubber tubing.

Also just a reminder that if, when injecting CO2, the gas seems to be going everywhere except into the keg there’s a good chance this o-ring has been stretched or damaged and is no longer sealing around the neck of the CO2 bottle. It can be replaced and just sits in a groove.

By far the most common cause of trouble is the pressure-release rubber and it’s doubly frustrating for people because it almost always fails without any sign of failure! Huh?

The large brown rubber seal in the image below is the one that allows gas to escape when pressure exceeds a safe threshold – you’ll remember the gas escapes through the hole behind the rubber seal. What happens though if the rubber has become stretched and is not gripping tightly enough? The answer of course is that it will allow gas to escape at lower pressures, maybe no presure at all if the rubber is really slack. This is exactly what happens and is almost always the explanation for a leak you can’t seem to trace. The perfect-looking rubber seal in the image on the left and in the middle is the same stretched rubber you can see in the image on the right (shown next to a new rubber seal for comparison). The rubber seal streches over time and looses elasticity so although it looks fine it allows all your precious CO2 escape.

I use one of these sleeve expanders to fit the new rubber seal but it can be done with a couple of watchmakers screwdrivers or other strong & thin implements but of course be wary of nicking or piercing the rubber. When you seat the rubber seal make sure it’s centred around the groove to get the best seal.

 

[Chippy_Tea]

Brilliant and well worth a sticky

 

[Hazelwood Brewery]

Fitting the cap

Just screw it on – right? Actually, yes! You do need to make sure it well tightened though and you’re going to need a cap spanner for that. Some people use Vaseline on the cap or smeared on the rubber seal, you can do this by all means - it may help to effect a seal and it will help reduce friction as the cap screws down onto the rubber seal so might also make it easier to tighten.

I will re-emphasise though - you need to make sure the cap is tight. There is no point trying to seal the thread around the neck of the King Keg - for example using PTFE tape because the seal is achieved only on the top lip of the opening on the keg, where the rubber seal in the cap presses down on the mating surface. Some people sand this surface with very fine paper but I’ve never found this necessary and you might create a problem for yourself if you're not precise and level.

Some people replace the round-profile rubber seal that's supplied with a flattened square-profile seal. Again, I’ve never found this necessary and actually I believe the round profile of the original seal takes up any surface imperfections on the keg more readily than trying to squash down a square profile seal.

Older King Kegs were supplied with a clear hard plastic seal for the cap, more recent versions are supplied with a softer black seal that does a better job. You can buy these separately if you have one of the older hard clear plastic seals and struggle with it.

Next up, testing....

 

[terrym]

Thanks Chippy, bit more to do before I’ve finished.

Good posts.
I'm glad someone has at last taken the initiative to put together a catch all for all the little and some no so little tricks required to keep a PB going. Hopefully it will be the forum reference point, and previous multiple threads on this subject which often cover the same problems and solutions will become a thing of the past.

 

[Rodcx500z]

Nice write there award yourself a saison

 

[LesTom]

Excellent and very informative write-up, you've got me interested in buying a pressure barrel

 

[Drunkula]

Excellent and very informative write-up, you've got me interested in buying a pressure barrel

There are alternatives that aren't actually randomly cursed as they leave the factory. If you're young enough and see that you'll be brewing for a good few years don't sell yourself into the slavery and cognitive dissonance of pressure barrels.

 

[Buffers brewery]

What!? No fettling!?
Excellent write up @Hazelwood Brewery .
I've tamed my King Kegs (for now) by replacing the whole closure assembly. No screw cap. No S30 valve. No agro!

 

[Buffers brewery]

There are alternatives that aren't actually randomly cursed as they leave the factory. If you're young enough and see that you'll be brewing for a good few years don't sell yourself into the slavery and cognitive dissonance of pressure barrels.

You had a bad experience with PBs?

 

[terrym]

You had a bad experience with PBs?

And he's not the only one.
But this thread will be an excellent way to help those who own a PB to get the best out of them, given their problems.
And hopefully not a shop window to convince the uninitiated to plunge into buying one without having duly weighed up the pros and cons of ownership.

 

[Clint]

That's a great write up H...I like your liberal use of the word FLANGE.

 

[Buffers brewery]

And he's not the only one.
But this thread will be an excellent way to help those who own a PB to get the best out of them, given their problems.
And hopefully not a shop window to convince the uninitiated to plunge into buying one without having duly weighed up the pros and cons of ownership.

You had a bad experience with PBs?

 

[Hazelwood Brewery]

I should say don’t be put off by the length of all this content, I’ve tried to cover several configurations and problems that people might experience.

I currently have 11 King Kegs in constant use and thinking about another. I have virtually no problems whatever because I use the PTFE tape, I fit a cable tie, I know how tight things needs to be, I replace the pressure-release rubber, and I buy the keg with the black tap. Easy.

 

[Buffers brewery]

Always good to hear some positive thoughts about pressure barrels, King Kegs in particular, as like all commodities, there's a price scale that usually reflects the quality scale. A little unfair to tar all PBs with the same cheap brush....IMO. Good, positive thread