How to change output pressure on a regulator ninja tank

[FuzzyGrub]

Just saying thank-you for an old thread.  I recently purchased a bunch of ninja regs, top hats, shims, Belville's, package deal.  I wanted to convert one reg back to 800-850psi output, to use for a SBR auto-BB gun.  This thread had everything needed to do that.  I do have to wait on some 1.8k burst disks to test it. 

Anyway, thanks to Bob for producing it and GTA for keeping the old information available. 

[nervoustrigger]

John, if your regulator pistons have the little 4mm plastic ball on the end, PM me your address so I can put a few Delrin replacements in an envelope for you.  The OEM part is nylon and tends to wear or take a compression set before too long which leads to pressure creep.  I have more than I need and would rather they be put to good use.

https://www.gatewaytoairguns.org/GTA/index.php?topic=179050

[FuzzyGrub]

John, if your regulator pistons have the little 4mm plastic ball on the end, PM me your address so I can put a few Delrin replacements in an envelope for you.  The OEM part is nylon and tends to wear or take a compression set before too long which leads to pressure creep.  I have more than I need and would rather they be put to good use.

https://www.gatewaytoairguns.org/GTA/index.php?topic=179050

Thank-you very much for the info and the delrin balls.   

[FuzzyGrub]

I received the burst disks today.  Aired up, and it is right where Bob estimated it would be, 800psi.     The next time I degas, will add a 0.005" shim to get to 850psi. 

[nervoustrigger]

Note, swapping out the softer nylon ball with Delrin will very likely drop the setpoint slightly.  I won’t hazard a guess as to how much but I would start with an extra 0.005” shim.

[FuzzyGrub]

Note, swapping out the softer nylon ball with Delrin will very likely drop the setpoint slightly.  I won’t hazard a guess as to how much but I would start with an extra 0.005” shim.

Thx, I have 0.010" shims, so will go with one of those. 

[Nvreloader]

Jason
I am NOT sure this reg creep info,
 
Does it mean that the pressure goes and or down during reg creep?

I have had problems with a well used Ninja reg holding a uniform pressure, with variations in pressure,
seen during testing etc.

Thank you,
Don

[nervoustrigger]

Hi Don, creep will always manifest as a gradual increase of pressure in the plenum.  It’s caused by the valve seat coming together and almost sealing but not quite completely.  Air molecules continue to slowly migrate through microscopic imperfections (scratches, machining marks, etc.) until it finally climbs high enough to squish the seal fully closed.  Depending on the severity of it and how the hammer spring tension is dialed in, it may cause the first shot to have a higher velocity, a lower velocity, or no noticeable difference whatsoever.
 
There really should never be a meaningful pressure _drop_ in the plenum.  For example,  if there is a considerable drop in temperature, the pressure will fall and the regulator’s valve seat will respond by opening up and topping off the pressure.  It’s not 100% perfect—there’s some hysteresis—but it seems to be a close enough approximation in my experience.

[FuzzyGrub]

Note, swapping out the softer nylon ball with Delrin will very likely drop the setpoint slightly.  I won’t hazard a guess as to how much but I would start with an extra 0.005” shim.

With the ball change and 0.010” shim, output was right at 900psi.