From the product description, check product page for current description, price and availability:
The Blow Tie Spunding Valve is used to release excess pressure on a pressurized fermenter or from a receiving keg during pressure transfers. This diaphragm spunding valve is much more accurate than the spring and poppet style, and works much better at lower pressures.
The BlowTie 2 features an integrated pressure gauge so you can quickly and easily dial in your pressure setting. The gauge is removable and can be swapped out with a gauge of a different pressure range.
Pressure Fermentation
Pressure fermentation is becoming more and more popular at the homebrew level, but in order to do it safely and accurately you need a way to release excess pressure. You’ll pressurize your vessel to your desired psi, but once fermentation begins and those hungry, active yeast start creating CO2, the pressure inside the vessel will increase. Attach a spunding valve and set it to your desired pressure, and it will blow off when the pressure gets too high and close up again when it’s back to your desired psi.
Pressure Transfers
Even if you don’t have a pressurizable fermenter, you may have done pressure transfers from keg to keg during filtering or after fining. During pressure transfers, it’s a good idea to have a bit of head pressure in the receiving keg, especially if you’re transferring beer that is already carbonated. Having a spunding valve in place will allow you to consistently control the head pressure and give you more consistent results, without losing carbonation in the process.
Diaphragm vs. Poppet
With the poppet style spunding valve, a spring pushes against a poppet to keep the valve closed. When the poppet lifts up to open, the surface area the gas pushes against becomes larger, and the spring has to work harder to push the poppet down and reseal the valve. This can lead to more gas being released than intended, and the remaining pressure in your vessel may be at a lower psi than your spunding valve’s set psi.
Instead of a poppet, the spring inside the BlowTie pushes against a diaphragm, which has an immensely larger surface area. This means the surface area that the gas pushes against while the diaphragm is closed is significantly closer to the surface area it pushes against when the diaphragm is open. This leads to higher accuracy, and the remaining pressure after excess gas is released will be much closer to your set blow off pressure.
Set Up
The BlowTie spunding valve comes with 8 mm Duotight fittings on the inlet and outlet, and we recommend using it with EVABarrier 8 mm OD tubing (D1717 or D1718). You’ll also need the flare Duotight fitting (DUO106) in order to attach it to a ball lock or pin lock disconnect. Dialing in your desired pressure is even easier with the BlowTie 2, thanks to the integrated pressure gauge. Simply start with the adjustment knob fully closed, then slowly open it until the gauge reading matches your desired pressure setting.
Specifications:
- Made from food grade acetal
- Stainless screws
- Easily disassembles for cleaning
- 8mm (5/16″) Duotight fittings at both ends
- Interchangeable pressure gauge
- Gauge reads from 0-23 psi
WARNING: Do not exceed gauge pressure. Exceeding the pressure range will damage the gauge.
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The components I used for this build. See below for parts list.
A look at the Primefit CR1401G Replacement Air Regulator with steel-Protected Gauge, 1/4″ Npt
Bottom view of the completed assembly
A top down look at the assembly. For a Spunding Valve application the red pressure knob clearly visible here is not particularly helpful. The PRV is doing the heavy lifting. I set this to full flow.
Another version utilizing the a BlowTie PRV valve.
