O-ring and lubrication: what type to choose and how to apply it

Jun 13, 2023

When they say that it is the details that make the difference, it is true. Today we discuss a crucial detail in diving equipment: o-rings and their proper lubrication.

First of all, everything related to the study and knowledge of these important technical details are subjects of study in the path to becoming a Wase Diveducation dive instructor, which allows one not only to become an instructor but also a deep connoisseur of the "irons of the trade."

Let's start by saying what an o-ring is: a gasket made of "O"-shaped silicone or nitrile rubber, of various sizes, used as a seal in a joint.

When choosing an o-ring, one should not choose hydraulic o-rings, but high-pressure gas-tight ones, because they last longer. Another very important factor, especially in professional diving, is hardness. The hardness of rubber O-ring seals is measured in Shore (Sh), a variable strength parameter according to a scale defined as follows: from 0 Sh for soft materials, up to 100 Sh for harder materials, but we will talk more about this next time.

O-rings can be found in the cylinder fittings at the first stage attachment point, in the first stage itself in the high and low pressure hose attachment, in camera housings, in the buttons and openings of diving lights and flashlights, etc...

To make them last and to maintain their function, it is necessary to lubricate them. But how? And most importantly, what kind of lubricant to choose?

Let's start by saying that the lubricant chosen should be able to perform the dual function of nonstick and sealant at the same time, thus preventing the gaskets from sticking to the metal or material on which they work and resisting weathering and washout.

Cleaning and therefore maintenance products must be compatible with the chemical material of the installed o-ring.

In the case of common o-rings that are used in air cylinder fittings, and electronic equipment, it is important that the lubricant be a silicone grease. This material will have the function of lubricating, waterproofing and protecting the o-ring. What is more, silicone grease is a material that works at temperatures that can range from -40°C to 200°C.

For proper application, a veil of it is sufficient. First you take the o-ring out of the installation, slide it between your thumb and forefinger to feel if there are any dents or breakage points to see if you need to replace it or not, then again using your thumb and forefinger moistened with silicone, grease it over the entire surface. Too little silicone would not perform its function well and too much would over-grease the equipment.

Finally, it is good to store spare o-rings (because a good diver can also be recognized by the spare parts kit he or she carries with him or her) in a dry place at room temperature, away from direct sunlight and ozone sources. The best solution then is to store them in sealed polyethylene bags.

We've talked about silicone grease as a great lubricant--but will it always be good for all types of o-rings? Let us know what you think in the comments.

In the meantime, get ready for next time, because we are going to go and choose a dive diving center.

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