Unexpected Injector Failure Cause

[Builder01]

Brown is the new Black........ahem........sorry Bill.

[hoppercar]

i was reading, that the manufacturers of viton o rings, dont recommend them for steam service

[Bill Shields]

that is true...even more so with buna....

Viton has been shown over the decades to be OK in the 100 psi steam range for static seals, packing and even piston rings. BvB's steam pumps are all built with Viton O-Rings and generally run just fine.

There are better compounds available now...but I have several 1000 Viton rings of various sizes that I will continue to use.

[hoppercar]

i think the problem with these valves I purchased, is the fact, when you pull them open, the o ring comes out of the bore....this constant going on and out of the bore, tends to cut the o ring

[Chris Hollands]

FYI - Viton o rings can be ordered in various colors and markings
Brown and lite green are very common and are used too verify the o ring is different from a standard o ring .
Also you will find black or brown o rings with little green dots on them which is also used to signal the o ring is Viton .
Equipment spare parts kits especially for hydraulics components use this format extensively .
Green o rings are more expensive than brown and brown is more expensive than black .

[Bill Shields]

i use the 'pill bottle marking method'.

that and the fact that I never order anything except viton or silicone (which is RED).

[Greg_Lewis]

i was reading, that the manufacturers of viton o rings, dont recommend them for steam service

Consider that "steam service" is a rather all-inclusive term that includes temperatures and pressures much higher than what we have in our applications. One source I checked lists the working temperature of a Viton o-ring as up to 440°F, while superheated steam in industrial situations would be much hotter.

[hoppercar]

look in msc catalog, at the o ring chart....it grades viton as poor, for steam service...

[Bill Shields]

I would prefer to look at specific applications (temp / pressure) for a given material than take a reseller's generic rating..as an engineer..that's what I do..

'steam service' is a very broad brush with which to paint a canvas.

[hoppercar]

me too...I've used viton, and it's ok In most applications, but I prefer to use aflas.....even the manufacturer of viton, does not recommend it for steam or hot water

[10 Wheeler Rob]

Is this O ring designed to have radial compression between the valve steem and housing with adequate axiel clearance to allow for expansion? Or is being squeezed axiel like a graphite packing? If its being squeezed then its going to expand in the trapped volume and tend to do what's happening.

Rob