The Ocean Design Small O-Ring Kit (NBR) is a dive O-ring kit with 18 different sizes of Nitrile Rubber (NBR) O-rings, 10 of each size, 180 O-rings in total. It includes three multi-use brass O-ring picks. Kit comes in a top load sectioned plastic box (with labelled cover) for organising all the different size O-rings.
If you work on dive gear you know the importance of having the correct O-rings. Many of the O-rings used on cylinders, valves and regulator hoses are pretty much generic. Having a large selection of common O-rings is a must for the serious technical diver.
Included in this Divers O-ring Kit, Professional Quality, NBR 70 Shore A are:
AS568-003 10 PCS
AS568-006 10 PCS
AS568-007 10 PCS
AS568-008 10 PCS
AS568-010 10 PCS
AS568-011 15 PCS
AS568-012 15 PCS
AS568-013 15 PCS
AS568-014 15 PCS
AS568-015 10 PCS
AS568-016 10 PCS
AS568-019 10 PCS
AS568-022 10 PCS
AS568-023 10 PCS
AS568-024 10 PCS
AS568-025 10 PCS
AS568-112 10 PCS
AS568-214 10 PCS
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 serviceable' SCUBA applications are fairly regular, so it's probably best to choose the size based upon the application.
||SCUBA Application Seal
||Cylinder with Large Neck/Valve (3/4 NPS - All Aluminium, most Steel cylinders)
||Cylinder with Small Neck/Valve (7/8 UNF - "Genesis" 3500 psi Steel cylinders)
||Standard DIN Regulator/Valve (Nearly all DIN regulators)
||Small DIN Regulator/Valve (You know if you need this one)
||Cylinder Valve Bonnet Nut
||Standard Yoke Regulator/K-valve
||Large Low-Pressure Port/Hose (1/2 UNF)
||High-Pressure Port/Hose (7/16 UNF) Manifold and Manifold Port Plugs
||Standard Low-Pressure Port/Hose (3/8 UNF)
||Low-Pressure Hose/2nd Stage Regulator Cylinder Valve Stem
||BC Power Inflator
||High-Pressure Hose/SPG swivel
O-rings can be made of a very long list of exotic materials and most are inappropriate for SCUBA applications. The materials commonly used in SCUBA applications appear in the following table.
(NBR or Nitrile)
|Most O-rings used in SCUBA are made from Nitrile, a hydrocarbon based synthetic rubber. Nitrile offers excellent resistance to many oils and acids and has good physical properties. However, Nitrile is not a very oxygen resistant material and is not considered oxygen compatible. Nitrile is also often referred to as Buna-N.
|O-rings made of FKM have been the preferred choice for oxygen and nitrox compatibility in SCUBA diving applications. FKM is an elastomer with excellent oil and oxygen resistance at high and low temperatures, very good chemical resistance. Even for use with ordinary air, most experts agree that FKM O-rings outperform common Nitrile O-rings.
|The milky white O-ring occasionally seen in the face of K-valves, sometimes called a 10,000 psi O-ring, is made of Polyurethane. Polyurethane is very abrasion-resistant, but it is sensitive to UV light (sunlight).
|Ethylene Propylene Diene Monomer
|EPDM O-rings are becoming more common in SCUBA because some people feel it's a safer material for use in breathing air systems. EPDM is a elastomer with excellent weatherability, heat resistance, dielectric qualities and odour-free characteristics. However, EPDM is less resilient and is not recommended for use with petroleum derivatives.
O-rings are normally available with a hardness rating, as measured by an ASTM type-A durometer, of 70 (the "soft" kind) or more rarely a rating of 90 (the "stiff" kind). The soft O-rings are appropriate for dynamic applications where the O-ring is providing a seal with a constantly moving part, such as inside regulators. The stiff O-rings are more durable in static applications where the O-ring is providing a seal with stationary or occasionally moving parts, such as a valve.
O-rings are available in nearly any colour, although most commonly seen in black. Most Viton O-rings are black. The Viton O-rings typically sold for scuba diving are brown, simply to make them easily distinguishable from Nitrile O-rings which are usually black and EPDM O-rings which are often purple. Just to be clear, the COLOUR of the O-ring is MEANINGLESS. Some people believe there is a difference in quality based on colour, but that is more likely attributed to unknowingly using soft dynamic O-rings in static applications. Our O-ring manufacturer states there is little difference in quality for O-rings based on colour alone, and independent testing supports that statement. Some people also incorrectly believe a Viton O-ring can be distinguished from a Nitrile O-ring by the surface appearance. Nitrile O-rings are said to have a shiny surface, and Viton O-rings are said to have a matte surface. This is not a reliable indicator, and certainly not true if the O-ring has been lubricated.
3-Piece Brass O-Ring Picks
This three piece brass O-ring pick set is specifically designed for removal and placement of O-rings, but we use them for all sorts of other tasks. The brass tips won't scratch soft seating surfaces in valves, regulators or other equipment and the colour coded plastic handles have a comfortable ridged grip. Two of the tools have a sharp point and work well for removal, the third has a tiny ball on the end and is nice for placement. The set of three tools are in a re-sealable plastic package to help keep them organized and clean.
Designers of modern SCUBA equipment often specify O-rings with special properties and materials for specific uses inside their equipment. The special o-rings are supplied as part of original equipment manufacturer (OEM) service parts kits. Substituting any other generic O-ring just because it's the right size can cause difficult-to-diagnose problems and degrade performance. Improper service could cause a failure which would have serious and life threatening consequences.