Light Spring Schrader Valve Core?

Question

Hi,This question may be off-topic everywhere, but Google shows that people do talk about Schrader valves here...I needed to replace a leaking valve core in the unloader valve of my air compressor's pressure switch. Ordinary tire valve cores have a spring much too strong for the unloader's actuator to open. The local auto parts shops have no clue about a special light-spring valve core. I finally remembered the pressure release in my automotive compression tester, and have temporarily stolen that core for the compressor switch. Which means I still need the special core, just less urgently.If it was a brand-name compressor I'd try for a replacement part, but it was home-made from surplus parts many years ago. The compression tester is also an antique. But the fact that I have two devices with the same light- spring valve core must mean they are available somewhere. Google found that water well snifter valves also use a light-spring Schrader, but hasn't shown me any place to just buy a replacement core. Does anyone have any clues?Loren

Gerald Miller · Accepted Answer

How about clipping a couple of loops off a standard one to decreasethe existing compression?Gerry :-)}London, Canada

Bob Paulin · Answer

Gerald Miller  wrote in article...Cutting a spring INCREASES its rate.

larry g · Answer

Snap-On sells replacement Schrader valves for compression testers.  Chasedown a truck or call or if your friendly with a mechanic who deals withSnap-On have her get on for you.lgno neat sig line.

Gerald Miller · Answer

But it would DECREASE the effort required for initial deflection sincethere would be less pressure exerted by the shortened spring.Gerry :-)}London, Canada

"PrecisionMachinisT" · Answer

All the clues point towards your local well drilling folks maybe having one,have you tried calling them ???

Peter DiVergilio · Answer

Sorry I missed the initial post, but A/C Schrader Valves used in Automobileapplications have very light spring tension. You should be able to find themin JC Whitney or Grainger. Hope this helps (or have I missed the whole point[again])

Loren Amelang · Answer

Sounds like a plan that would provide a new, fresh one. Thanks to all for the ideas!Loren

Loren Amelang · Answer

The local auto parts store looked up some of those and said the sizes and threads were different from the standard tire valve size that matches what I need. I don't know anything about A/C... What I need is exactly like a tire valve, except for the very light spring.

The local pump guys only deal with modern submersibles and bladder tanks. (I just went through a failure of my old windmill-style sucker rod pump system, so I'm _too_ familiar with available resources.) I have since found that Dean Bennett in CO sells the snifter valves by mail, and they're not a major expense. If Snap-On doesn't work out, I'll try that.

Loren

Bob Paulin · Answer

Gerald Miller  wrote in article...If you cut the spring, then stretch it so it applies the same originalpressure to keep the valve closed, it will require MORE pressure to unseatthe valve since the spring now has a higher spring rate.If you cut the spring, but leave it so it doesn't apply the same originalvalve seat pressure - as you seem to be suggesting -  you have,effectively, re-engineered the entire Schrader valve, and it is likely tonot function correctly without the correct amount of spring tension workingto seat the valve and hold the valve seated.

Gerald Miller · Answer

To each, his own.Gerry :-)}London, Canada

clare · Answer

Gerry's method has been used successfully on compression testers. Youjust keep trimming the spring untill the valve doesn't close any more,then grab another one and cut off just a WEE tad less.

Light Spring Schrader Valve Core?

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