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Continued from previous post



4: O-Rings Buying Guide​


The easiest way to purchase O-rings is in pre-packaged rebuild or soft-goods kits. That relieves you having to determine the correct size, material, and Durometer required. However, it is also the most expensive method by a significant margin. Divers that want to buy from industrial O-ring suppliers may find the following information useful.

Measurements​


View attachment 432101
Most O-Ring suppliers measure them by the ID (Inside Diameter) and the Width or Thickness (cross-sectional diameter).

View attachment 432238
The vast majority of O-ring cross sections are round, but not all. For example, the Quad or X-Rings.

As a rule, round cross sections are assumed unless otherwise specified. The Width or Thickness can be measured with calipers or O-ring gauges.

View attachment 432102
Parker O-ring sizing cone and tape gauge

Material​

You can specify the material you want or most suppliers can help you determine the proper replacement material from a sample. Don’t be fooled into thinking that color is a reliable indicator. It is not.

Metal O-Rings are available for ultra-high pressures and/or purity, high temperatures, and for corrosive materials. They are seldom used in diving applications. Materials commonly used in diving applications are listed in Post #3.

Durometer​

Durometer is the O-Ring material's hardness, or resistance to indentation. Albert Ferdinand Shore developed the Shore Hardness Scale and instrument in the 1920s. "Durometer" is used in the O-Ring industry for the value and the instrument that measures Shore hardness of resilient materials.

Most industrial O-ring suppliers have instruments to check material Durometer and will test samples for you at the counter. Gauges are available for under $100 but are rarely required. Most O-rings used in diving applications are 70 to 90 Durometer but selecting the correct one can be critical.

Making Custom O-rings​

It is rare that custom O-rings are needed in the recreational Scuba industry, but commercial and military divers frequently encounter them. Larger O-rings required for chamber hatches, viewports, and mating trunks are seldom available and quantities are too small to justify such large tooling for custom production runs.

Extruded O-ring stock is available in large cross-sectional widths and a variety of materials. Formulations of Cyanoacrylate (like Superglue) adhesives are sold specifically for splicing O-ring stock.


Pro Tips​


Bonding machinery is available for more critical O-ring splicing applications.

Commercial divers and chamber technicians will often see full and half dovetail O-ring glands (grooves) in:
  • Chamber and utility lock doors and hatches
  • Bell and chamber mating flanges
  • Chamber to chamber bolt flanges
  • Hydraulic and pneumatic flanges and end bells
Changing O-rings can be tricky. This video might help

I'm embarrassed to admit how many times I started pressing an O-ring in a chamber door's half-dovetail groove from one point, worked my way around, and ended up with more O-ring than groove. Naturally all the old hands were watching the "new guy" demonstrate that I deserved that title.


Continued in the next post


Where can I get more information on that?
 
That sound about right but :idk: for surel
 
https://www.shearwater.com/products/peregrine/

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