Mixing 1st / 2nd Stages

[Cdncoldwater]

Exactly what tbone 1004 said.

It is preferred to set the 2nd with the assigned 1st mainly because the IP can differ between manufactures and the breathing effort specs can differ as well. When I service regs I do it as a set, if the end user mixes and matches after then that's up to them and not my responsibility. Manufacture training will stipulate not to mix brands and most LDS follow this as they need to follow the rules of the supplier.

 

[tbone1004]

Are there those that are suggesting that depending on whos second you are using. the secondary IP range will fall out of spec for teh 1st stage setting. Are there secondaries that are so narrow that they will not perform well if outside a 5psi range that is different than the 10 psi range of another brand. Am I wrong to be thinking that a wirst stage IP is like 130-150. It would seam to me that secondaries should all work between 135 and 145. Then itf there were a 5 psi window for a socondary. is there any real consequence in its performance if it is a little outside its BEST p[perating range. BEST and functional so often can not be sensed by the user. I have swaped sescondaies many times over teh years and have noticed no difference. This logic also suggests that you can not change a IE s600 for another s600 if the tuning is that critical for its unique differences.

On balanced second stages with balanced first stages, if tuned to spec, you can mix and match without any real consequence freely. That said, if the second was tuned hot at 130, and the first stage is at 145, it will likely freeflow. If the opposite is true, there can actually be a pretty noticeable difference in performance and the second stage may be out of spec for cracking effort. Will it matter to most people? Probably not, but it's how you're supposed to do it.

 

[jale]

This is one thing to follow manufacturer's "diktats" and another to use common sense.
Facing potential hassle by some ignorant shops doesn't mean it is not possible or forbidden or that it should not be done.
By the way, don't put brand X tyres on your car because the manufacturer says it should be brand Y...

 

[Cdncoldwater]

KWS,

I don't think anyone is suggesting that, I'm not, most manufacturers have similar specs and in this case the OP was using a ScubaPro 1st and Atomic 2nd so they weren't developed together so it's not as simple as switch within brand / series.

As mentioned likely very doable but not every shop will do it and may want the 1st stage the 2nd will be paired with; what a person does after or on their own is their responsibility.

 

[jale]

KWS,
I don't think anyone is suggesting that, I'm not, most manufacturers have similar specs and in this case the OP was using a ScubaPro 1st and Atomic 2nd so they weren't developed together so it's not as simple as switch within brand / series.

Well, if you believe so...

 

[Cdncoldwater]

jale,

What about liability? A shop records serial numbers and if there's a failure and there is an injury or death then maybe they have this policy as part of their liability coverage.

 

[Cdncoldwater]

Well, if you believe so...

jale,

What I believe and what I'm told when I take a manufactures course aren't necessarily the same but if you work for a shop then you follow the manufacture and owners rules. Like I said before what a user does after it leaves the shop is up to them.

 

[tbone1004]

This is one thing to follow manufacturer's "diktats" and another to use common sense.
Facing potential hassle by some ignorant shops doesn't mean it is not possible or forbidden or that it should not be done.
By the way, don't put brand X tyres on your car because the manufacturer says it should be brand Y...

it's not necessarily ignorant shops. They have dealership agreements that limit what they are allowed to service, and many of them include restrictions that prohibit mixing and matching regulators.
It is very much not like putting x and y brand tires on a car, that would be something like hoses. There isn't a good vehicle analogy for this situation.

Based on you spelling it tyres, I'll assume you're from the UK and in that case mixing them may well be straight up illegal for a shop to do since it would violate the CE ratings. What you do on your own is obviously very different

 

[HKGuns]

I have to say I am completely confused now by the diversity of responses.

 

[lexvil]

Do

I have to say I am completely confused now by the diversity of responses.

your own service, mix and match to your hearts content.