SP Compatible First and Second Stages

[FrankPro1]

I was wondering which 2nd stage ScubaPro Reg's are compatible with which ScubaPro 1rst stages? I am looking to get a G250 for my Mk2 and saw in my ScubaPro manual it states that the G250hp is not compatible with the Mk2 and does not list the G250/G250v. I'm also looking to hookup a G200B, G250 and R109 to a mk17 or 11. Is there a website or post that lists all compatible 1rst and Second stages? I searched around on the SP website and couldn't find anything.

I know that its usually an issue of the 1rst stage giving the second stage a proper IP range, but don't know enough about the technical side of things to understand it all. Any help would be much appreciated!

Also if anyone knows of a good tech in southern california "Los Angeles, South Bay area", that services Mk17 or other SP Diaphragm 1rst stages? "my local store is adamant about not selling or servicing Scubapro Diaphragm 1rst stages"

Another question that I'm gonna squeeze in this post: If a piece of equipment that I buy locally or online "outside of an LDS" that has been recently serviced, is it safe for me to install such piece onto my stage? Is it just a simple process removing a cap and screwing in the 2nd stage? or is it much more intricate then that?

 

[jac11819]

All the G250's were made to be compatible with a balance 1st stage. Your MK2 is not balanced but, your MK17 and MK11 are, therefore it would be compatible with your G250. Now, the G250 can be used with your MK2 but, it will not be able to do what it was design for, adjustability. The G200B or R190, either one would be a better 2nd stage for you MK2.

I'm not in So Cal, so I cannot recommend anyone to service your equipment. Good luck with finding someone.

As far as installing a gauge, octo, etc... It's really not hard, just a lot of sense.

 

[FrankPro1]

Now, the G250 can be used with your MK2 but, it will not be able to do what it was design for, adjustability. The G200B or R190, either one would be a better 2nd stage for you MK2.

So if I install a G250 onto my Mk2 it wont be adjustable? So I can't turn up or down the cracking pressure on the 2nd stage? I'm really new to scuba "not to diving" and really don't understand alot of the technical aspects of the equipment. Can you explain the mechanics behind this? What will happen if I adjust it while mounted on the Mk2? Nothing?

 

[Couv]

So if I install a G250 onto my Mk2 it wont be adjustable? So I can't turn up or down the cracking pressure on the 2nd stage? I'm really new to scuba "not to diving" and really don't understand alot of the technical aspects of the equipment. Can you explain the mechanics behind this? What will happen if I adjust it while mounted on the Mk2? Nothing?

Hello Frank,

I can not imagine why SP or anyone would say that the MK2 is not compatible with the G250 or any of the SP second stages.….they are. In fact, for use with an unbalanced first stage like the MK2 I like an adjustable and balanced second stage like the BA or G250. This allows the tech to tune the regulator to minimum inhalation resistance with the option of the diver increasing the resistance it if he/she finds the need. Yes, the diver adjustment knob will work fine.

As far as explaining the mechanics, well, DA, Luis or one of the other Usual Suspects can do probably do a better job than me. Later I will look for a link, but for now think of it this way: Behind the adjuster knob is a spring. As you turn the adjuster in, it adds more spring pressure which increases the cracking pressure.

couv

Edit: Here is a thread you will enjoy. http://www.scubaboard.com/forums/regulators/206355-pneumatically-balanced-2nd-really-true-3.html

Here is a link with animation you may find helpful:
http://diver.net/capture/musac.cs.man.ac.uk/regs/regs.htm

 

[DA Aquamaster]

The post mentioned will pretty much cover it.

In short though SP will pair any second stage with any first stage, you just have to order them separately. All SP regs/stages run in the same IP range of 120-145 psi and any second stage can be be tuned to the specific first stage.

As stated in that thread there are sometimes great reasons to pair a balanced second stage with an unbalanced first stage (my deco regs for example are all set up that way)

In addition, pairing a balanced second stage with an unbalanced first stage will give you a lot more bang for the buck in terms of ease of breathing at recreational depths than going with a balanced first stage and and unbalanced second, as while the balanced first will have more flow rate, an unbalanced second stage will normally be hearder breathing regardless of what first stage is feeding it. So if you can only afford one high end stage, get the balanced second stage. No company packages them that way however as in most recreational diving situations, doing so would negate the need to ever buy a high end balanced first stage.

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Some very old school SP dealers still refuse to sell diaphragm first stages. If I were king of SP, they would not be dealers much longer as it is a bias that has long since ceased to have any bearing in fact and I really hate ignorant LDS owners with a passion.

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If you have issues finding a local dealer to service a Mk 17, let me or cdreamer here on the board know and we could make arrangements to do it by mail.

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In terms of mechanics and features, the G200B is equivalant to the S555, the G250 is virtually identical to the G250V and the R109 is a G250 with a metal case and no flow vane adjustment. Any of them would work great with a Mk 11 or Mk 17.

 

[FrankPro1]

Thanks Couv and AquaMaster. You've helped to clear up alot