Which o-ring material

[Cbourbeau32]

When ordering o-rings which do you choose? 

 

[M0ist0ne]

I'm a buna 70/90 guy unless it specifically calls for a certain material. 

 

[thumper]

For most all sealing purposes in a PCP, Buna is best. 

 

[KatoKevin454]

Buna Nitrile, all others are for chemical or Hydraulic applications.

 

[nervoustrig]

Agreed, for static O-rings, Buna-N in 70 durometer up to 3000psi. Step up to 90 durometer for higher pressures. The harder material resists extrusion failure better but is at greater risk of getting damaged on installation… using 90 durometer everywhere is fine if you can get it installed.

For dynamic O-rings (those subject to movement), Buna-N remains a good all-around material but polyurethane may hold up longer, especially if it is subject to a lot of abrasion. That’s true of the more common injection-molded polyurethane but cast polyurethane (Disogrin) is even better.