To grease or not to grease?

[Bopper]

When I started scuba diving one of my instructors mentioned applying a small amt of silicone grease around my dive light O-rings to create a more waterproof seal. Then I came across other divers who also applied said grease to their regulator O-rings to - presumably - create a better seal there too. Also I've heard that it preserves the rubber and inhibits oxidation and drying out. And I'd imagine there's less chance of damaging the O ring when screwing and unscrewing the hoses when they have a light film of silicone. I thought what the heck and started applying it there as well.

Just recently I came across a blurb about equipment repair and maintenance and it mentioned that you really should only be greasing "moving parts". These regulator O rings are not moving parts. But for me I don't see the drawbacks of periodically applying a thin film of grease to these rubber rings.


Opinions? Experiences?

 

[Dsix36]

If the o-ring is dynamic then by all means put some grease on it. This will prevent premature wear and failure.

If the o-ring is static (trapped and can not move) then do not put any grease on it. The one time movement of the initial installation will not cause excessive damage. If it is greased it will be much easier for the o-ring to extrude when pressurized and cause a leak.

 

[knotical]

from: http://www.anchorrubber.com/specialty/parker_o-lube.pdf

3.1.5 Lubrication
Lubrication of O-ring seals is extremely important for installation and operation of dynamic seals as well as proper seating of static seals. The general rule for use of lubrication is: The greatest benefit in using a lubricant is obtained during the initial installation of the O-ring.

In a properly designed device, with the proper O-ring and lubricant, extrusion should not be an issue.

 

[divebunnie]

Whilst an O ring is not exactly a moving part, it does need to move slightly in order to create a good seal and this is where the silicone comes in handy.

Just enough to make the O' ring look glossy is enough to allow any movement it needs as the seal is closed, thus ensuring it is water tight. Too much however and it can cause the seal to leak.

However do not use silicone to lubricate any O rings on regulator hoses that are to be used with high mixes of O2 (above 40%) as these hoses should use non flammable lubricants and be properly "O2 cleaned".

 

[highdesert]

Bopper -

Be very careful about using the term "grease" as either a generic noun or verb as it applies to O-rings. Many (most) can be lubricated, lightly, with your basic silicone grease. Other O-rings, which require a more proprietary blend of lube, will swell and break down if exposed to silicone. Be well aware of that important detail!

 

[Kronek]

Unless the manual says to grease or lube it. I generally leave my orings dry. If you put DOW55 on it. It will expand, however DOW33 will cause it to shrink. Silicone will leave it the same. Petroleum based lube will eat orings in hours. There is too much to chance unless the manual says lube this much, with this kind of lube.

 

[Nemrod]

Well, for one thing, silicone grease is not correct for use with nitrox compatible equipment. For a second thing, while I do not think that is most cases a bit of lubricant (of the correct type) is harmful to static O ring applications, it is generally not considered useful and could result in failure by extrusion. Neoprene, buna, edpm O rings are compatible with silicone, nitrox aside. Silicone O rings, not generally used in regulators but common in photo gear, are not. It gets complicated, y'all figure it out.

N

 

[knotical]

… Other O-rings, which require a more proprietary blend of lube, will swell and break down if exposed to silicone...

Could you elaborate (e.g. what materials), and/or provide references?

… If you put DOW55 on it. It will expand, however DOW33 will cause it to shrink...

What materials are affected that way?

thanks

 

[j2s]

Follow the manufacture's recommendations.......