These Sonar Scuba O-rings are size BS1806/AS568-112, with a hardness durometer of 75, and made from FPM/FKM/Viton® Fluorocarbon Elastomers which are the preferred choice for oxygen and nitrox compatibility in SCUBA diving applications.
This is the O-ring size typically used at the front and back of the DIN insert used to convert standard DIN valves to INT/Yoke valves. These are the O-rings we prefer to use on the San-o-Sub DIN/K valves on Faber steel cylinders that are being used for Nitrox or Oxygen.
They are also the standard size DIN O-rings used on the male DIN fitting of many brands of first stage regulators that screws into and seals to the female DIN fitting on the cylinder valve.
V75-112 - O-ring Brown FPM 75 Duro BS112, 0.487 x 0.103"
BS112 O-Ring Size
||SCUBA Application Seal
|Standard DIN Regulator/Valve
(Nearly all DIN regulators)
Duro: FPM 75
Standard dimensions: CS 0.103" x ID 0.487"
Metric dimensions: CS 2.62 mm x ID 12.37 mm
Nominal fractional dimensions: CS 3/32" x ID 1/2"
FPM O-Ring Material
Fluorocarbon Elastomers (FPM/FKM/Viton®)
O-rings made of FPM/FKM/Viton® have been the preferred choice for oxygen and nitrox compatibility in SCUBA diving applications.
FPM/FKM/Viton® 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 FPM/FKM/Viton® O-rings outperform common Nitrile O-rings.
The Difference between FPM, FKM and Viton®
The terms FPM, FKM and Viton® very often cause confusion and lead to incorrect interpretations.
All of these designations actually stand for one single base material: fluoro rubber.
- FPM is the international abbreviation according to DIN/ISO.
- FKM is the short form for the fluoroelastomer category according to the American standard ASTM.
- Viton® is the registered trade mark of DuPont Performance Elastomers.