Blowtie spunding valve review

I’ve been using the blowtie spunding valve for about 2 years now. So, it’s about time I gave it a bit of a review and write up.

I purchased this online from Kegland for less than £20, to be used as a spunding valve on my converted keg fermentor. It’s been extremely reliable, and has proven to be easy to clean with my brewing pump and some brewing cleaner.

Occasionally I’ll take the unit apart completely just to make sure there is no mould or filth caught in the housing or the rubber membrane. So far it’s been clean on opening, and hasn’t needed further cleaning.

As pictured below, I use the blowtie spunding valve on my converted keg fermentor. Whenever I start fermentation, I always use an open blow-off tube for the first couple of days. That way, if there is any krausen blown off, it doesn’t clog up the spunding valve right from the get go.

Once I’m happy that any risk has passed, then I’ll change over to the spunding valve, and initially just have it at full open, which gives about 1 psi of pressure. As fermentation starts to slow, then I wind up the valve and start holding the pressure.

The valve is surprisingly stable at the pressure it holds, considering how lightweight the plastic seems. It is obviously stiff enough in the body of the unit, to not deform.

As the fermentation ceases, then I increase the temperature for a diacetal rest ( I mostly do lagers in this fermentor). This is where I find a performance difference between my stainless spunding valve and the blow-tie.

The stainless valve holds a stable pressure as the temperature rises, however, the blow-tie increases pressure by about 2 – 3 psi with a temperature rise of 10°c. Is this a problem? No, not really. If I needed a certain pressure, I could just wind it down again as I bring the temperature up. Also, as the temperature rises, the pressure in the fermentor needs to rise to maintain the same level of carbonation. However, It does highlight the difference in temperature stability of the two materials. If that’s the biggest fault I can find, then for the price difference, I’d say it’s a pretty darn good product. The stainless valve costs about £100, the blow-tie costs about £20.

Cleaning and disassembly

Generally, I link up the valve to my pump and run some PBW/ChemClean through it, and then run some rinse water through to ‘clean out the cleaner’. This has always been enough, and any time I’ve opened it up to deep clean, the valve has always been spotless. The part that gets a bit mouldy perhaps, is the gauge stem. However, as it needs to be removed, and the tee piece plugged, in order to be able to pump through the valve, the gauge gets clean each time anyway.

So lets take a look at disassembly. Each push fit socket can be released by pushing in and holding the collar, and at the same time wiggling out the tube.

Disassembly of the BlowTie Spunding internals

Once the valve is detached, remove the yellow pressure adjustment screw, by fully unwinding. This will reveal a spring.

Tip the unit upside down and remove spring.

Now, carefully unscrew the four stainless screws.

Lifting the top off, reveals the inner workings. There are only three parts left here, don’t worry, there are no spring loaded parts left here. The white plastic disc you see is the base plate to spread the load from the spring onto the rubber membrane below.

Remove this white disc. You are now left with the rubber membrane that does all of the sealing and gas flow control. There will be no dirt here, there should never be any gas flow or blow-off in here.

Pick out the rubber membrane by pinching the small knob in the middle. This is where there will be any dirt, if it’s there.

We now have all the component parts. Clean as necessary.

How it works

A close up of the inside shows how the unit works. The CO2 enters the chamber to the outer ring, and then exerts a force on the rubber membrane. The amount of force exerted on the membrane and therefore the centre plug, controls the lifting of the plug and allows the gas to escape down the hole.The centre hole is otherwise blocked by the plug on the rubber membrane. The hole in the middle is where the gas leaves the chamber to the outlet tube.

Below, you can see the rubber membrane, and the ‘plug’.

Once reassembled and putting the tubes on, be shore to check the gas flow direction on the side. It is indicated by the arrow.

Although it is relatively easy to assemble and disassemble, I would make a small adjustment here. The edges of the tube is very sharp, and will eventually catch and cut the rubber o-rings inside, degrading the seal. I like to get a pencil sharpener, and just take a small amount off the corners. Once this is done, the tubes push in a great deal easier, and don’t catch the o-rings at all.

Conclusion

So, the final question with any product is, ‘Would I buy it again?’. Absolutely, yes. It’s simple, reliable, easy to clean and all of that for very little money. There is a new version out with an integrated pressure gauge which I would like to try. On the surface, this looks even better than the original, and i will need to get one to try out. When I do, I’ll put together a review much like this one.