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(09-06-2019, 01:31 AM)awemawson Wrote: What are you using as “lube” ?
My understanding is that no oils are allowed anywhere near oxygen valves, hose couplers and regulators.
Right you are Andrew. Hydrocarbon (petroleum) based oils should
never be used around oxygen. It is a fuel source that can be ignited quite easily when impacted with oxygen. Bad ju-ju.
Instead I am using
Krytox which is a fluorinated synthetic grease that is inflammable, chemically inert, and safe for use in oxygen systems. I believe it is commonly used in the aerospace industry among others due to it's resistance to both gaseous and liquid oxygen. I can tell you Krytox is extremely expensive though. But when nothing else will do...
I also used it when I rebuilt my regulators. I only wipe enough on to put a 'sheen' on the surface of seals & slip rings before assembly. You certainly don't want to glob it on. I have a .5 oz (14.8 ml) syringe of it that would last me several hundred lifetimes. But that was the smallest amount I could buy.
Willie
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The Teflon that McMaster sells is quite hard. I have some, and while it machines fairly well, it's not soft, like Delrin.
I would think that you would want something softer for the packing, to kind of "squish" around the stem as you tighten the packing nut.
Full of ideas, but slow to produce parts
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(09-07-2019, 07:59 AM)rleete Wrote: The Teflon that McMaster sells is quite hard. I have some, and while it machines fairly well, it's not soft, like Delrin.
I would think that you would want something softer for the packing, to kind of "squish" around the stem as you tighten the packing nut.
There are different grades of Teflon and McMaster carries some of them. You may want to consider Durable PFA. Just a thought.
Posts: 4,443
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Location: Missouri, USA
(09-07-2019, 07:59 AM)rleete Wrote: The Teflon that McMaster sells is quite hard. I have some, and while it machines fairly well, it's not soft, like Delrin.
I would think that you would want something softer for the packing, to kind of "squish" around the stem as you tighten the packing nut.
You must have a different flavor of Teflon. Delrin hardness (McMaster): Rockwell R120-R122 (Hard)
1/2" PTFE rod (McMaster): Durometer 50D-65D (Medium Soft)
The real fly in the ointment though is that Delrin is flammable and is non-self extinguishing. It doesn't stop burning until available oxygen is used up or removed. Note in the description - "Must not (be) used for Oxygen service."
Valve Seat Material guide.pdf (Size: 88.76 KB / Downloads: 2)
Willie
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(09-07-2019, 10:12 AM)Dr Stan Wrote: There are different grades of Teflon and McMaster carries some of them. You may want to consider Durable PFA. Just a thought.
Thanks Stan but...
1/2" PTFE rod ~ $2.56 per ft.
1/2" Durable PFA rod ~ $56.92 per ft.
Willie
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YOUZER!