What happens if you deviate from a manual’s pairing chart?

[MacDuyver]

pairing charts in the back of reg manuals are pretty limited.

Aside from the ubiquitous “you’ll probably die” what are those pairings based on and what happens when you deviate from them and use a not-approved 1st/2nd stage pairing?

 

[L13]

Most 2nd stages are completely fine with most 1st stages, as long as they are tuned to the same intermediate pressure.

If the 2nd stage is balanced, you even have a fair amount of leeway in IP before you will notice any difference.

(however, if one is more limited in flow rate at depth or more prone to freezing etc., you will not see the benefit of the less limiting one)

 

[jborg]

Most 2nd stages are completely fine with most 1st stages, as long as they are tuned to the same intermediate pressure.

And just to be completely clear for the OP, this is not just "within the pairing table for a given manufacturer" but "across all regulators from all manufacturers everywhere (with a few uncommon exceptions)".

 

[Nemrod]

The pairing charts are the combos marketed and which were tested to CE standards. Nobody but me would purchase G260 second stages and then pair them with a little Mark 2 Evo so that combo is not shown in the chart because it was not tested for certification. However, it works just fine at and beyond any sport diving depth and mine has been to 150 feet in cold water in TRL on the Kimberling Bridge. Oh, wait, that was a G250, not the G260, I think, not sure I recall now.

A balanced second stage will pair well with an unbalanced first, an unbalanced second stage will pair well with a good balanced first stage. But an unbalanced first (ex SP Mark 2) will not necessarily pair well with an unbalanced second stage (SP095/190/195) though such combinations are often made.

 

[BoundForElsewhere]

pairing charts in the back of reg manuals are pretty limited.

Aside from the ubiquitous “you’ll probably die” what are those pairings based on and what happens when you deviate from them and use a not-approved 1st/2nd stage pairing?

you turn into a sea cucumber.

has anyone ever seen an attractive sea cucumber? they should be called sea turds.

 

[Eric Sedletzky]

The pairing charts are the combos marketed and which were tested to CE standards. Nobody but me would purchase G260 second stages and then pair them with a little Mark 2 Evo so that combo is not shown in the chart because it was not tested for certification. However, it works just fine at and beyond any sport diving depth and mine has been to 150 feet in cold water in TRL on the Kimberling Bridge. Oh, wait, that was a G250, not the G260, I think, not sure I recall now.

A balanced second stage will pair well with an unbalanced first, an unbalanced second stage will pair well with a good balanced first stage. But an unbalanced first (ex SP Mark 2) will not necessarily pair well with an unbalanced second stage (SP095/190/195) though such combinations are often made.

I think the reason they pair a MK2/R195 is just for an economy option.
If an anal retentive saw some of my pairings it would send them straight into therapy.

 

[Nemrod]

I think the reason they pair a MK2/R195 is just for an economy option.
If an anal retentive saw some of my pairings it would send them straight to therapy.

I think that is what I mean, it works, but is not ideal and it (195 with Mark 2) apparently met CE cert. And it is adequate for once a year pretty fish dives. But pair that Mark 2 Evo with a G260 and I doubt most would know difference between it and a Mark 17/19/25, I cannot anyways.