Help with spunding valve

Brewing Processes
1

I build a spunding valve with the standard setup based around the  control systems pressure relief valve. I can’t seem to get any predictable results out of it. My process is

Pressurize an empty keg above where I want to end up

attach spunding valve and allow pressure to head towards where I want. As it gets closer I gradually slow the release until I finally stop it at my pressure. I’ve left it for days like this and its stayed where I stopped it

The issue is when I repressure the keg to test setting is a crap shoot where it ends up. Sometimes it’ll stop way before sometimes way below.

Any advice ? I know a lot of people are using it and making it wirk

2

I use my regulator to dial in the setting I want and then move it to the keg

3

From Sean:

  1. Attach the spunding valve to the liquid-out post of the (empty!) keg.
  2. Tighten the PRV to maximum pressure.
  3. Pressurize the keg via the gas-in post until the pressure gauge is reading somewhat higher than desired.
  4. Slowly back off the PRV until gas begins to flow.
  5. Once the gauge has dropped to the desired pressure, tighten the PRV until audible flow stops, then an additional one-quarter turn.

http://seanterrill.com/2015/06/25/build-a-better-spunding-valve/