O2 Compatible O-Rings, Lubricant and Tools
We stock a variety of O-Rings suitable for use in SCUBA applications. Society of Automotive Engineers AS568B is an Aerospace Standard that specifies sizes for O-Rings used in sealing applications. An AS568B number is a three-digit suffix that identifies the O-Ring's size. Technically, an O-Ring size is listed as AS568B-016, AS568B-112, etc., but most people use just the three-digit number. The first digit denotes the O-Ring cross section width: 0xx = 1/16-inch, 1xx = 3/32-inch, 2xx = 1/8-inch. While it might seem convenient to provide a picture sizing chart, we've never seen an online version that could be reproduced exactly in a Web browser. Also, sizing an existing O-Ring that has been in service can be error prone because O-Rings can take a set that changes their dimensions enough to be misleading. Luckily, the sizes used in 'user servicable' SCUBA applications are fairly regular, so it's probably best to choose the size based upon the application.
|AS568B-||Outside Diameter||SCUBA Application Seal|
|214||1-1/4||Cylinder with Large Neck/Valve (3/4 NPS - All Aluminum, most Steel cylinders)|
|116||15/16||Cylinder with Small Neck/Valve (7/8 UNF - "Genesis" 3500 psi Steel cylinders)|
|112||11/16||Standard DIN Regulator/Valve (Nearly all DIN regulators)|
|111||5/8||Small DIN Regulator/Valve (You know if you need this one)|
|015||11/16||Cylinder Valve Bonnet Nut|
|014||5/8||Standard Yoke Regulator/K-valve|
|013||9/16||Large Low-Pressure Port/Hose (1/2 UNF)|
|012||1/2||High-Pressure Port/Hose (7/16 UNF) Manifold and Manifold Port Plugs|
|011||7/16||Standard Low-Pressure Port/Hose (3/8 UNF)|
|010||3/8||Low-Pressure Hose/2nd Stage Regulator Cylinder Valve Stem|
|006||1/4||BC Power Inflator|
|003||3/16||High-Pressure Hose/SPG swivel|
How Much and Where to Use Lubricant
Some people very sparingly lubricate the SPG swivel O-rings, but you should know that SPG and hose assemblies from our suppliers are never lubricated. If you do choose lube the SPG swivel o-rings, take care not to be so generous that lube might migrate up into the Bourdon tube mechanism and cause your SPG to become inaccurate. Some people also sparingly lubricate the threads of valves before they are installed in the cylinder neck. Do NOT lubricate the neck O-ring itself, and do not lubricate the valve/regulator seal O-ring or DIN threads. Most lubricant is used with dynamic seals in regulators and other equipment with moving parts. As a general rule, the O-rings used with static seals in SCUBA applications should not be lubricated at all. The lubricant just causes contamination to stick to the surface of the O-ring and results in more problems with a static seal than any dubious benefit the lubricant might provide.
Dive Gear Express only sells lubricants that are supplied directly from the factory in their carefully selected packaging, but some other retailers are purchasing in bulk containers and then repackaging it in smaller sizes. Aerospace Lubricants has advised us this is an unapproved and possibly unsafe practice. These unapproved package types contain mold release agents, silcone treated rubber stoppers in the syringes, and dyes in colored containers, all of which can leach into the lubricant itself. These containers, along with the repackaging conditions themselves, are certain to produce lubricants which are contaminated and no longer suitable for oxygen service.