Scuba Pro Regs and 1st service problems

[scubadobadoo]

My wife and I recently had our mk25/550 and mk25/s600 Scuba Pro regs serviced for the first time. They are both now one year old and have performed very well. I recall from my equipment specialty class that regs can often free flow a tiny bit when newly serviced. Well, this seems to be happening to us now. Not a big deal but it made us a little worried while diving this past weekend.

Pushing the purge button may cause the air to continue to flow a little or diving into current may push against the purge button resulting in a tiny bit of air to also freeflow. Also, my wife complained that she used more air than she normally does perhaps due to the higher air flow rate. You get the drift. So, should I take them back and ask them to tune them back a little or will this issue slowly go away over time? Is it that big of a deal anyway and is it really that normal? Thanks in advance gang!

 

[DA Aquamaster]

What happens is that the soft seat in the second stage acquires a seating groove which is an entirely normal process. This is normally not a big issue as the factory specified cracking effort adjustment is so high that the formation of a seating groove does not result in a freeflow.

However a tech will often attempt to get maximum performance and minimum cracking effort out of the second stage, which is a good thing as the regulator will breath much easier. But when doing this, the effects of the seating groove forming become important and these effects have to be accommodated. Normally the tech tries to anticpate the effect at annual service by adjusting the orifice about 1/12th turn past the optimum setting so that when the seating effect occurs, the reg will not leak. This normally works quite well but sometimes the tech gets it wrong.

To take some of the uncertaintly out of this adjustment the tech can:

1) Leave the reg setting for a week and then readjust the orifice, or

2) Leave the reg pressurized 6-8 hours before making the final adjustment, or

3) Use a machine (if available) designed to cycle the second stage poppet rapidly and break in the soft seat before making the final adjustment.

1 & 2 are often not practical in many shops and 3 requires the dive shop to have the proper equipment, which is still a relatively new development.

In any event, since the tech got your regs adjusted slightly too light, they will not get better and if anything will get worse over time so the regs should be readjusted. The good news is that this is a 5 minute fix that the tech will do for free and the problem will not occur again.

This problem makes sense for the S550 as it is a non adjustable reg. But on the S600, turning the adjustment knob in slightly should resolve the problem. (I normally set the orifice on adjustable regs so that they are on the verge of a slight freeflow with the knob all the way out which allows max performance but also leave plenty of adjustment range.) If turning the knob in slightly does not resolve the problem, the S600 is either way out of adjustment or the Mk 25 has a problem with a leaky high pressure seat causing the intermediate presure to creep up well beyond the acceptable range. So the IP is worth checking also and this should occur during the re-adjustment process anyway.

 

[scubadobadoo]

Thanks DA! As usual, you provide excellent and correct info. I just dialed mine back and my wife took hers in for a quick 5 minute fix as you suggested. Problem solved! Let me add that I have loved my mk25/s600 thus far! A really smooth breather. I had a Dacor Fury before and it breathed like a rusty muffler compared to the scuba pro!

 

[Hoosier]

I agree with him. I have also mk25/s600. I don't have any complaints.
After having DA Aquamaster's expertise, I am looking for MK16/G250HP for the independent setup. Maybe, MK17/G250HP, but I am sure when this model hit U.S. market.

 

[Hoosier]

Wait! Where has your reg service done?

It was LP?

I just would like to have the updatee service experience with LP. Thanks!

Thanks DA! As usual, you provide excellent and correct info. I just dialed mine back and my wife took hers in for a quick 5 minute fix as you suggested. Problem solved! Let me add that I have loved my mk25/s600 thus far! A really smooth breather. I had a Dacor Fury before and it breathed like a rusty muffler compared to the scuba pro!

 

[scubadobadoo]

Thanks DA! As usual, you provide excellent and correct info. I just dialed mine back and my wife took hers in for a quick 5 minute fix as you suggested. Problem solved! Let me add that I have loved my mk25/s600 thus far! A really smooth breather. I had a Dacor Fury before and it breathed like a rusty muffler compared to the scuba pro!

My previous post above details the service update that took place. BTW hoosier, have you had a chance to try the twin jets yet? Hope ya like them!