Thread sealant for gauge?

Teflon Pipe Dope. Don't use tape. It can have a little piece tear off during installation and jam up the circuit flow of the run or imbed itself in something.

Rob

Fraser Competition Engines Chicago, IL.

When I have removed old gauges there was no sealant. I would go dry and comparatively tight. You can always put a sealant on if you cannot get a leak free connection. I have a feeling that the particular pipe tread form is intended for full contact/engagement. Randy

Now my question is, what kind of thread sealant, if any, is used?

John

Gauges with NPTF (dryseal) threads are very rare. These are tapered pipe threads but differ from standard NPT because they have a tightly controlled thread form on the crest of the male thread and also on the root of the female thread. The regulator would also have to have an NPTF female thread. Without this control most NPT threads will leak out the spiral leakage path because of the male thread crest is almost always larger than the female root. It is this spiral leakage path that the pipe tape or dope seals. My preference is for tape. Even when assembling NPTF joints I still use tape unless at least one part is plastic. The reason is most joints end up with similar metals and similar metals have a nasty habit of galling, usually just before the joint in sufficiently tightened enough to seal. Using a lubricant is not recommended if for no other reason to avoid inadvertently using it on an oxygen gage. If you have taken off old gages that did not appear to have sealant you may be overlooking the presence of an anaerobic sealant, which is common in OEMs.

FWIW, the torch pressure gauge had dope seal on it, and the tank pressure gauge looked like it had teflon tape on the threads.

John