Leaky ball valves

[timben]

Just geting started in casting
I am trying to set up my presure pot. I puchased 1/4 ntp ball valves at HD and they seem to be leaking through the top where the nut holds the lever in place. I tried 2 valves to eliminate a defective valve with the same result.
I can actually hear, feel air leaking at 40 psi. Do I need to use 1/2 inch valves with adapters? Is there a way to adjust the valves.
I also noticed that my presure relief valve kicks in at only 40 psi. the pot is rated at 50 psi. Is there any way to adjust the relief valve, or should I purchase a new one. If so where can I get them?
Thanks,
Tim

 

[Druid]

Tim,
I had the same issue with HD, after trying the third one I went to another brand/manufacture. The ones I have on now are designed for pressure (pneumatic) & gas, they are made of one solid piece and not two or three sections. I think I bought them at Lowe's but it might have been HD, just in another department. When I go out that way I'll try and look it up. I know I use one PP with a Husky pneumatic ball joint and it holds well. Make sure your using the pipe thread tape when assembling.

Hope this helps.

 

[RHunter]

I also noticed that my presure relief valve kicks in at only 40 psi. the pot is rated at 50 psi. Is there any way to adjust the relief valve, or should I purchase a new one. If so where can I get them?
Thanks,
Tim

Tim,

Surplus Center has lots of air fittings- I ordered from them when I built my PP.

Here is a link to a 75psi Safety Relief Valve. If your PP is rated only for 50psi, you would need to be VERY careful not to exceed that since this popoff valve would still be intact at the burst strength of your PP. But posted ratings are always lower than the actual burst strength- but I wouldn't recommend betting on that...

Are you using the Harbor Freight PP? Mine is rated for 80psi max...

-Doug

 

[RAdams]

I hear "Depends" works pretty good for a leaky ball valve.



sorry. couldn't resist.

 

[timben]

Thanks for the help Jim and Doug.
Surplus Center turned out to be a real good resource for fittings, They have the relief valves and pretty much everything else you need to set up a P.P. and they are much cheaper than local places. My pot is not HF they are back-ordered, so I picked one up on ebay to get started.
Don't worry Ron, I hit 50 a few years ago...The depends will be needed soon enough

 

[Druid]

Food for thought....

This may not have been the safest thing to do but it was my weakest link in my Pressure Pot system, I removed the Safety Relief Valve. I just set my compressor to push/hold the total PSI I want to achieve and watch the gauge. I do not use my pots as a dual purpose pressure/vacuum since I already have a very large 22" x 15" 6 gallon with top feed vacuum chamber that pulls 28.5 mg/in (top pull at my sea level elevation). My PP system is very streamlined, and all my pots were tested and hold a min of 63 PSI for 24 hrs with no leakage. I would also suggest inserting an elbow inside the the pot lid fitting at the pressure inflow fitting, this helps deflect the air along with the PP casting shelf Curtis designed (designed with deflector shield). It will reduce (if not eliminate) resin "blow-outs" from the molds.

Hope this helps.