This testing device comprises of a tube containing a specific magnitude weight (Figure 6 labeled A). The weight descends a predetermined distance for each material, as shown on Figure 6.

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. In the USA the Society of Automotive Engineers (S.A.E.) publishes AS568B as an Aerospace Standard that specifies sizes for O-rings used in sealing applications. The equivalent British Standards Institution publication is BS1806, which lists all Imperial standard sizes. This standard includes all of the 5 main cross section groups in AS568, plus several sizes that are "between" AS568 sizes. In Australia BS1806 is widely referenced in many industries, including the dive industry. The groove in the Cressi and Poseidon brand regulator DIN connectors measures closest to the original standard, best accepting a BS ISO 3601 metric size O-ring with 11.3 X 2.4 dimensions for which there is no imperial standard equivalent. The M2.4X11.3 size O-ring is uncommon, especially in a material suitable for use with Nitrox. (FYI, the O-ring in Yoke K-valves is easy, it is always an 014 size.) Extraction and Insertion damage is reduced. Using metal objects to remove O Rings can cause damage to the housing and equipment which then create a leak path that affects the integrity of the seal

O-Ring Hardness

stage inlet fittings; HP seal retainer seal; J valve module; Valve HP plugs; 2nd stage barrel and housing plug seals, Shewood 5121-106, Scubapro 1,050,158, Apeks: AP1267 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). The application parameters should be considered when choosing the appropriate lubricant. The lubricant chosen must be: An O-ring is a doughnut, or torus shaped seal typically used to prevent the passing of air or fluid. In other words, O-rings are used to keep fluid or air IN or OUT of a defined space. For example, an underwater camera housing uses O-rings to keep water out, and scuba regulators use O-rings to prevent precious air from escaping.

However, if you aren't well versed in the technical aspect of scuba gear, it's only advisable to attempt to change the O-ring on a scuba cylinder/tank valve (Yoke), or the face of your DIN regulator. Leave other O-rings for experienced professionals. The information that follows should help you to know more about the O-rings used in various scuba diving applications. O-Ring Sizing

High-viscosity silicone oil: High viscosity silicone oil is an ideal all-purpose o-ring lubricant. It is an incredibly efficient seal lubricant and can be utilized in temperatures between -54 𐩑C - 204 𐩑C (-65 𐩑F - 400 𐩑F).