A dab of silicone grease on hose fittings?

When connecting hoses to first or second stages, would it be a good idea to put a dab of silicone grease on the threads?

I know that some threaded fasteners should be lubricated to achieve the correct torque, and for others, the torque spec assumes the fastener is dry.

Are there any shop manuals that expressly address lubrication of hose fittings being connected to regulators? Is there a general custom of not lubing the fittings?

Ricky B:

When connecting hoses to first or second stages, would it be a good idea to put a dab of silicone grease on the threads? ...//...

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The threads will be fine if you don't overtorque them, just remember that stainless steel galls.

Forget silicone grease. The O-Rings will greatly benefit from the smallest amount of O2 Lube or any other oxygen safe lubricant. *expensive*

Most regulator bodies and fittings are chrome plated brass though with the EPA driving manufacturing offshore where it goes unregulated and they dump everything into the sea, we are likely to see other material like stainless and new coating material to provide wear and corrosion resistance.

You do not need to put silicone on the threads, does it hurt anything, no. However, it could lead to O ring extrusion if the hose goes a little loose.

N

Nemrod:

Most regulator bodies and fittings are chrome plated brass. ...

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Better than my answer. True.

A bit of oxygen safe lube still doesn't hurt either the O-Rings or the threads though...

Please don't use silicon. Invest in a packet of oxygen safe lube. A lot of shops stock it, and you can order it online, and it doesn't create a combustion risk if you mess up and lube rings that may see high o2 concentrations.

The shop manuals for a lot of regs can be found online for free, and may or may not address kubrication. Some do, but I haven't read them all. What reg do you use? Might be able to point you in the right direction?

Unless you are using very high levels of O2 in your regs there is no reason at all not to use silicone grease, on the hose orings or in the regs themselves. No need for it on the threads since they should remain dry. Even at high O2 levels it is only a concern at high pressures gradients. "You must use O2 safe grease" is pure myth buster material.

Reg Manuals and Diagrams are much much different. You miss out on the lube specifics, torque specs, and adjustment procedures if you just get the Blow-Up Diagrams that are found on the internet.

True there are some actual repair manuals out there for your older regs such as pre 2000's Sherwoods, Scubapro 109's, Mk5s etc etc.

I don't suggest lube on threads. Best you can do is take a very thin film of lube, rub it into your finger tips, then swirl the Oring along your fingertips. The Oring should look glossy at most, or have no change in appearance.

All you're doing with this procedure is:
1) Making sure the Oring isn't bone dry or brittle (you can do this visually and use lube if needed, but honestly I would use a different Oring if that's the case)
2) using your lube fingers to swipe any lint away (but lubed orings do attract lint more if you drop it right after you lube it)

Realistically you don't need lube on the static orings, like those on the hose threads going into the first stage.
You don't even really need it on the LP Regulator side, the pressure is so low that your hose will turn the same with or without lube.
HP hoses are a different story, lubing up your SPG Spools can make a difference.

Silicone lube is fine, but it washes away and degrades easily. O2 lube will still be there when you open up your Reg for it's next service. What ever you want to take from that.
I would only really push the O2 lube when lubing SPG spools and gumming up Dynamic Orings in your first stage. Otherwise your other connections won't make a difference what lube you use (assuming you're not O2 cleaning).

Now days, I don't mix and match out of principle when I service, but if you're just doing parts here and there yourself it's fine. I've used silicone all my time before getting officially tech certified. No problems mixing second stages with silicone lube while my first stage was O2 lubed.

I wasn't spending the $$$$ on O2 lube when all I was doing was hose changes and second stage rebuilds on my bed.

I've used a dab of silicone grease on O rings for decades. The hose O rings get a light film as does my valve O rings. I put silicone grease on my fingers when handling O rings so they always have fresh lube applied. As stated unless you're using 100% O2 some where you'll be fine.

Since this thread has understandably wandered away from just lubricating threads (which I don't) to include discussion about lubricating O-rings (which I do) - a comment on static O-rings:

Static O-rings are at least somewhat dynamic during installation and therefore benefit from lubrication.

If the threads are exposed to water intrusion such as threads on IP adjuster screw, yoke screw, 2nd stage hose connection at the second stage, etc. I use silicone. There it is not exposed to breathing gas and prevents corrosion in the threads. Threads sealed by an O ring do not need it, the O ring does.