O-ring specs

[emoreira]

Hi, I'm rebuilding an old TUSA TR-200 1st stage regulator. I could get from Frogkick the explosion diagram with part IDs.
All the o-ring dimensions are listed, but there is no mention of the o-ring specs.
I have a Parker Hannifin O-ring catalog.
Which is the material used for the o-rings ?
Among the options the one that most fit should be N3006-90A followed by N3000-70A.
Any idea which is the one used ?
Thanks.

 

[tbone1004]

depends on what the o-ring is doing. I rebuild mine with nitrile because they're cheap, but not to be used with O2 regulators.

I use 90a durometer for all port plugs, and other mostly static applications. Not sure of the exact schematics of that regulator, but the 70a o-rings are used in places like the HP swivel at the SPG and other similar environments

 

[Hickdive]

Most regulator o rings are Nitrile and 70 shore.

Viton o rings are typically 90 shore, which is a bit hard for the moving parts of some regulators.

The insistence on Viton o rings in nitrox regulators is a bit old-fashioned. Apeks and Aqualung, for example, no longer supply "nitrox" service kits with Viton rings. Instead they have Nitrile with the recommendation that they be cleaned before installation in a regulator intended for use with Nitrox blends 40% or richer.

 

[redacted]

Nitrile tends to be less expensive but it also has the shortest shelf life and can suffer accelerated deterioration in high O2 applications. I usually stick with EPDM or viton depending on price and availability. I use duro 70 or 75 unless the application has an extrusion problem as they are generally easier to work with and may seal better if there are any sealing surface defects. HP piston o-rings are usually vulnerable to extrusion so I use duro 90 for those.

 

[emoreira]

Thanks for the replies !

 

[halocline]

I like to use 70 duro in applications where there is not a huge pressure gradient and 90 where there is. But 70 will work fine in almost every spot except the HP piston stem o-ring. It's nice to have higher duro o-rings for the SPG spool as well.

EPDM or nitrile will be fine. The cost difference is minimal.

 

[redacted]

...except the HP piston stem o-ring. It's nice to have higher duro o-rings for the SPG spool as well.
.

FUN is slipping a couple duro 90 -003s over the ends of a spool!

 

[NotSure]

FUN is slipping a couple duro 90 -003s over the ends of a spool!

I have never had a problem getting duro 90 on the spool type on the right. Even with a special tool made for spool o-ring installation a duro 90 will split almost every time on the other spool type.

 

[halocline]

FUN is slipping a couple duro 90 -003s over the ends of a spool!

Steady hands and clean thoughts.

 

[Hickdive]

The trick with installing o rings on a spool is to place the new, lubricated, o ring in the palm of one hand and press the spool through the o ring.