Overhaul advise please

[Couv]

Hello All,

I will be tearing down and overhauling my regulators soon. I would like the opinion of the resident regulator gurus on the advantages or disadvantages of a couple of settings.

Let me start off by saying that I am now a warm water sissy diver and I would be using my regulators in water well above freezing. All of my 1st stages are Scuba Pro MK 10's and my 2nds are Scuba Pro Balanced Adjustable, G250 and a couple of AIR II second gens. I will be adjusting all of the 1st stages to the same IP (as near as possible anyway.)

1. I am aware of the advantages to a lower IP when a reg is used in cold water, but for non freezing conditions, should the IP be set near the upper end, toward the middle or near the low end of the specs?

2. Except my AIR II which I purposely set the cracking pressure a little higher, I usually I tune my 2nd stages for a very slight free flow when the adjustment knob is all the way out. A reg tech I worked with years ago suggested this "positive pressure" setting for personal regulators. Am I overlooking any disadvantages to this method?

OK gurus...DA, Awap, Captain, Dennis, Oxyhacker, you too Pesky Door, ;-) and anyone else in the know …weigh in on this.

Thank you,

couv

 

[captain]

Seems you are doing it the same way I tune my MK V and 109 ajustable second.
With the piston first stage IP changes have to be done with shims so generally if it falls in spec, I go with it. If it is a diaphragm first than IP ajustment is easy and I generally lean to the high side. With the 2nd turned to freeflow when tuned all the way out also puts a lighter force on the seat if you don't use a storage key to take the pressure off. Just don't over do the freeflow when turned all the way out.

 

[redacted]

I'm also a www. Low 50's is the worst I've been in and I have no intention of getting into water where the reg may freeze. But I tend to set IP in the 125 to 130 range. As the seat wears, it tends to creep up to about 135. I try to get every breath I can out of a seat before I change it. Habit probably from when parts were harder to come by.

I also try to set the 2nd up on the low cracking pressure side and then control it with the adjustment knob. My wife dives an Air2 and I like to keep the cracking pressure pretty low on that also. Just keep a 3/16th allen wrench in the save-a-dive kit if it starts to bubble. One of the allen wrenches on the scuba mult-tool is 3/16th. Scubapro recommends that last adjustment to stop a slight leak be made on the nylock nut rather than the orifice. So if I do a field adjustment, I'll touch it up again correctly when I get home.

I store all my 2nds with the purge depressed.

 

[DA Aquamaster]

I like to set my Balanced Adjustables and G250's the same way - with a very slight freeflow (just a faint hiss) when the knob is all the way out. This gives you maximum adjustment range and also ensures minimum pressure on the seat during storage.

The advantage of a higher IP in a first stage is a higher flow rate. It's a lot like turbocharging your car - more pressure means more airflow through a given space in a given period of time. The Mk 10 is a good reg in term sof flow rate but by modern standards is probably considered moderate at about 130-150 SCFM. It could consequently benefit from operating at the high end of the range if you use it for deep or technical diving. Other wise, you'll never need the extra airflow until you are well outside recreational limits anyway.

The Mk 10 mainsprings tend to stiffen slightly with age, so all other things being equal, a Mk 10 will tend to run with a higher IP at age 20 than it did when new. SP now includes 3 seats in the service kit to accommodate a wide range of IP's beyond what could be achieved by adding or removing shims so spring replacement is not normally required.

The Air 2 uses an unbalanced dual adjustment poppet design. I agree that it works best to leave the lever slightly loose until you make the final adjustment.

I tend to set my Air 2's to breathe close to the minimum effort possible for the design (about 1.4 to 1.6" of H20). It does not cause freeflow issues and when needed they breathe well and will not induce a feeling of being starved for air.

 

[Couv]

Thanks all.