Identical 1st stages for doubles?

[144000]

hi folks.. for diving in doubles, do we need to have identical 1st stages ? or can we have different first stages?

i was reading the GUE equipment config page but didnt find anything mention about this... so is this a personal choice or a mandate? to have identical first stages for both tanks??

 

[SparticleBrane]

Do you have to? No. No one is making you do anything.

Is it preferred? I'd say so, based on ease of servicing/replacement kits and interchangeability.

 

[Bismark]

Do you have to? No. No one is making you do anything.

Is it preferred? I'd say so, based on ease of servicing/replacement kits and interchangeability.

Like he said.

 

[wunat]

Do you have to? No. No one is making you do anything.

Is it preferred? I'd say so, based on ease of servicing/replacement kits and interchangeability.

DIR or not, I would say that it is certainly better to have the same first stages for your doubles. Reasons as said.........

 

[b1gcountry]

Just to be contrary:
If you have two different 1st stages, you could tell everyone you do it for reliability, with the idea that the set of conditions that would cause one reg to fail would have greater probably to cause the other to fail if they were the same model...

Tom

BTW, I pretty much pulled that out of my butt, but there's nothing to say it isn't true, eh?

 

[Charlie99]

Just to be contrary:
If you have two different 1st stages, you could tell everyone you do it for reliability, with the idea that the set of conditions that would cause one reg to fail would have greater probably to cause the other to fail if they were the same model...

Tom

BTW, I pretty much pulled that out of my butt, but there's nothing to say it isn't true, eh?

Actually, Richard Pyle did have such a failure on a rebreather dive to 300' or so. Both his diluent and his O2 regs failed for the same reason -- IIRC, the liquid or grease in the environmentally sealed ambient pressure chamber of the first had leaked out or evaporated. At depth the rubber cap covering the ambient chamber got forced in, preventing ambient pressure from reaching the ambient chamber, and the IP dropped with depth. Simultaneous failures of both of his regs and both of his buddy's regs.

A similar situation happened with a jetliner down in Miami a couple decades ago. All 4 engines failed, because the maintenance guy had left open an oil drain plug after servicing all 4 engines. They only made it back to the airport because they were able to restart the 1st engine that had failed.

 

[b1gcountry]

Aha! I'm really smart and didn't even know it!

...just as I always suspected

 

[lamont]

Just to be contrary:
If you have two different 1st stages, you could tell everyone you do it for reliability, with the idea that the set of conditions that would cause one reg to fail would have greater probably to cause the other to fail if they were the same model...

Tom

BTW, I pretty much pulled that out of my butt, but there's nothing to say it isn't true, eh?

In an IT security culture context, i've heard that referred to as avoiding monoculture. e.g., if you split your web farm into 3 sets composed of windows boxes, freebsd boxes and linux boxes, then a DDoS attack against the linux TCP/IP stack will only take out 1/3rd of your capacity. The problem is then you have to manage windows, freebsd and linux boxes in production at the same level of competency and the costs are usually too great (it is taking me years to take a company from basically having zero actually linux infrastructure to having a good linux management framework).