O-rings

My own reference material for O-rings and seals

Overview

Scuba diving uses a lot of different orings, made from various materials and durometers. As a general rule of thumb, a 70 duro is used for LP fittings and a 90 duro is used for HP fittings. However this is very much a loose rule of thumb and with life critical hardware one should always refer to their manufacturers servicing manual.

Manufacturers servicing manual, however, are not always available, or do not list the specification of the orings used, only an internal part number. Therefore I have kept track of the various sizes of oring that I have come across during my various projects, primarily for my own reference but it may come in useful for others as well.

Reference Table

Regulators

General

Standard Identifier Usage
AS568D 003 HP Swivel
AS568D 010 Second Stage Swivel Seal
AS568D 011 3/8” UNF (standard) LP Port
AS568D 012 7/16” UNF HP Port
AS568D 013 1/2” UNF (non-standard) LP Port
AS568D 014 Yoke Seal
AS568D 112 DIN Regulator Face Seal
AS568D 111 Small DIN Regulator Face Seal (Apeks)

HOG

Standard Identifier Usage
Proprietary O-S-8-04 D1 Sintered Filter Spacer
AS568D 006 D1/D3 HP Stem
Metric 2.42x0.82 Zenith Piston
AS568D 010 D3 Flow Through Orifice, Zenith Orifice
AS568D 011 D1/D3 DIN Port
AS568D 012 D3 DIN Retainer Nut
AS568D 013 D1 DIN Retainer Nut, D1 Turret Bolt O-Ring
AS568D 014 Zenith WOB Knob seal
AS568D 016 D3 Turret Body # 1
AS568D 019 D1 Turret Bolt, Zenith Barrel External Seal
AS568D 021 D3 Turret Body # 2
AS568D 024 D1/D3 Turret
AS568D 905 D3 Balance Chamber Plug

Apeks

Standard Identifier Usage
AS568D 011 Sintered Filter Spacer
AS568D 006 HP Stem
AS568D 013 Retainer Nut
AS568D 019 Turret Bolt
AS568D 024 Turret

Rebreathers

General

Standard Identifier Usage
AS568D 121 P-Port O-ring
AS568D 032 P-Port Thread O-ring
AS568D 121 SiTech Thread O-ring

Submatix

Standard Identifier Usage
Metric 28x3 S-connector O-ring
JIS G120 Radial seal scrubber
AS568D 008 MAV Barrel Seal
Metric 72x3 Submatix Head (2012)

KISS

Standard Identifier Usage
AS568D 028 KISS Classic Counterlung Port
AS568D 028 KISS sidewinder tower port

Misc

Standard Identifier Usage
AS568D 010 Aliexpress 8mm QC
AS568D 019 DGX/DIV03 Barrel
AS568D 116 M18 Valve Cylinder Neck
AS568D 214 3/4” Valve Cylinder Neck
Disclaimer: This information is provided for reference purposes only. While every effort has been made to ensure accuracy, specifications should be verified with manufacturer documentation before use in safety-critical applications. The author assumes no liability for errors or omissions.