So what are the consequences of using a different durometer?

[Euphie]

So my 4500 psi maxflo was creeping, I have a maxflo rebuild kit, but I notice the kit is all 70 durometer o-rings rather than the ones that are clearly harder that came off of the regulator. So it all seems to work fine, three hours pressurized and no reg creep whereas before it would raise about 100 psi every half an hour. Still what are the consequences of this?

I suppose I am a bit unsure of why any particular durometer is decided on by the engineers who design regulators or if it isn’t just a case of “these were used because they were cheaper”.

also is there a good place for place for buying individual o-rings?

[Jordan]

I think harder duro seals are used in high-wear/stress applications? Definitely for things like reg seats - softer works, but more likely to deform under pressure over time.

[Euphie]

That was one that worried me a bit, the maxflo had this odd two metal pieces sandwiching an o-ring seal and the one I pulled out of there almost felt like hard white plastic whereas I replaced it with a pretty soft feeling 70 durometer black o-ring. I suppose wear isn’t a huge issue for me though as I can just take things apart and fix them

[Jordan]

That's probably the only one I'd really worry about for durometer - that's the reg seat. I think it's a 009-90 durometer, and should really be urethane, although I've used buna in the past.

[Trbo323]

Pfff, for the most part, nothing

You MIGHT have to replace them a little more often. But seems like you are already measuring your rebuilds in decades so.... Yeah

For the regulator seat itself, I to to stick as close as I can to the original but that said I've had cases where I've had to change it and been just fine

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[Myrkul]

100% this. I rebuild everything with "O" Rings from ACE hardware store whenever possible. I am yet to run into any significant issues with anything except mags or dedicated liquid builds. Mags seem to be picky as hell, and liquid chews up buna pretty fast. Other then that you should be fine. My heavily used vertical max flows are all buna 70 and are going on 4 years with zero issues so far.

[MrBarraclough]

If the old o-rings had been on that reg for a long time and were urethane, age might exaggerate the difference in feel as the urethane o-rings may have hardened.

It also seems like 90 duro urethane was much more popular than bunanitrile in the 90s and early 2000s. A classic Automag has zero buna rings; they're all urethane except for like 1 or 2 PTFE. So maybe 90 duro was just the thing to use back when that MaxFlo was designed.

In terms of consequences of using 70 duro buna, it supposedly should translate into reduced wear resistance and therefore lifespan. Probably a tiny bit more likely to shred and blow little bits of debris through the reg if its a dynamic seal, but even then it's not exactly high wear. Doubt it would be an issue for anyone who regularly services their gear.

I'd be concerned enough to substitute urethane for buna only where there is high potential for friction and fairly long travel distance involved, such as the hammer on a blowback. 70 duo buna feels a little more "grabby" to me, whereas 90 duro urethane feels more inherently slick even before lubrication.

[PlawB]

The ONLY time I've ever found hardness and material to matter, it's inside of an automag valve.

[Euphie]

I think I have found an issue, pretty bad shootdown, it fires fine till about six shots a second and if you look at the pressure gauge it is clearly struggling to keep up. I can’t fathom by what method of action different o-rings could cause this though. I will put the right reg seat o-ring in there and hopefully that solves the issue. Otherwise I might have to look at my on/off valve or something.

[Jordan]

The ONLY time I've ever found hardness and material to matter, it's inside of an automag valve.

ICD Freestyles seem to be fussy, too.

[Cunha]

All the classic spoolies were fussy about O rings and probably especially lube especially if you are tuning the LPR to be as low as possible, so when there is a friction situation they will cycle weird.

Plus lube keeping stuff stuck in place would mean FSDO because of static friction or whatever.

[Araphel]

Aside from premature wear; at the pressures typically seen in hp regs, softer durometer o-rings can be extruded out of their glands. Also, regardless of hp or lp application, softer o rings can lead to wear issues by allowing metal components to contact each other. Components are designed with a certain amount of seal compression and hardness is a factor in that. Depending on manufacturing tolerances and component design, using lower durometer seals can result in leaks and higher durometer seals can result in excessive drag/wear. In general it's best to stick to whatever durometer the components came with.

[Trbo323]

All the classic spoolies were fussy about O rings and probably especially lube especially if you are tuning the LPR to be as low as possible, so when there is a friction situation they will cycle weird.

Plus lube keeping stuff stuck in place would mean FSDO because of static friction or whatever.

My experience is that this is the opposite

I own a dm6 that doesn't care one bit what's in it as long as the rings are good, it's happy. I've also done a FEP quest that was the same way

My brother in law has a 2013 rail that is super picky. Manual calls for an 015 poly 60duro, I had buna 60 on hand and poly 90s, it wouldn't accept either. It HAD to be a poly 60 for that marker to seal up

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[Cunha]

Mine were original matrix's so things maybe different. My lube choice and LPR pressure determined how smooth the gun felt but could also determine FSDO if lube had static friction or whatever. I ran quad O rings but I dunno if they made much difference.

What I meant was that my O rings and their exact sealing properties made a difference in the gun tuning. It could work fine with whatever O rings but to make it run optimal I would choose O rings that moved easily but still sealed.

So yeah I think my statement was overly broad. I always go out of my way to find the best possible O rings because I'm a weirdo, even for my tippmanns.