Gang, Quick question - without me having to do much experimentation, does anyone out there know if a grease fitting is made well enough to hold air pressure? I have an application in mind, but a normal schrader valve won't work, but a grease fitting (if silver soldered in position) probably would be okay. Thanks. Ken.
Assuming it would, are you willing to risk someone pumping grease into your widget by mistake?
Grease fittings have a spring loaded ball that seals the hole in the fitting. The heat of silver soldering will anneal the spring and seal will be lost.
Use JB Weld to seal the threads.
I suspect a normal grease fitting ball check would not be air tight. My Applied Industrial Technology catalog lists leaktight oil fittings which look the same.
Don Young
Not a grease fitting expert but my little loader / backhoe has 37 fittings and almost every one of them spits some grease back out after I put grease in. My bet would be they won't work for holding air.
Steve.
Look around for "presta" valves. They're like schrader valves, but a lot skinnier and definitely hold air. As cheap as going to a bike shop and asking for any dead inner tubes with presta valves in 'em. If you do go with a grease fitting, I suspect one made of brass (hard to find, but I've seen 'em before) would have a better chance of actually sealing air. You could also try adding a drop of air tool oil to help it.
I did not know a smaller variety of schrader valve was available.
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