Guide to Mares regulators from 2000-2020

[divezonescuba]

I once attended a service seminar by the Italian product development manager. When he pressurized the regset during the class, he always held down the purge button on the primary second stage. When it free flowed, he then released the purge button. He was adamant about that.

I did not understand why until your post just now. Apparently, some individual Mares regulators are prone to do that.

 

[Zef]

Hi, Mares experts
I have 6pcs MR22 regulators, and one has a problem that if the tank valve is opened quickly, a hi pressure pulse goes to the LP side (2nd stage acts as an overpressure valve). The regulator otherwise works well, but the others do not have a similar problem. I have replaced almost all the internal parts, but the problem does not go away

We need to know a couple more things to help help understand what is going on:

1. What is the intermediate pressure (IP) of the 1st stage in question?
2. Have you tried switching the 2nd stage that is problematic for another? If so, what was the result? If you haven't done this, could you, and then let us know the result?

It could be that the 1st stage IP is set too high.

It could also be that the 2nd stage in question has a cracking pressure that is set too hot/low.

It could be a combination of both the above.

I understand that divezonescuba presents the notion that the 2nd stage purge button should be depressed when opening the cylinder valve to to prevent 2nd stage freeflow.....I don't believe there is anything specific to Mares 1st stage design that would lend to the freeflow issue, and in my mind this is an issue of 2nd stages with cracking pressure set too hot. There is some thought in some diving circles that it is a best practice to depress the 2nd stage purge button when opening the cylinder valve, but for a different reason. The thought behind this practice is that with the valve closed and the hose between the 1st and 2nd stage unpressurized, there is very little pressure of the 1st stage poppet against the knife edge of the volcano orifice. When the valve is opened, it is believed the rapid pressure released into the 1st stage slams the poppet against the knife edge, leading to greater and unnecessary wear and tear on the poppet face as pressure on the HP side of the 1st stage goes instantly from 0psi to roughly 3000psi. It is believed that this "poppet slamming" is alleviated by momentarily holding the 2nd stage open when opening the valve. It is unknown to me whether this truly has any positive effect on reducing wear and tear on the internal parts of the 1st stage, but it makes logical sense to me and so it is a practice I adopted quite awhile ago.

Please answer the questions above, as your responses will help guide our thoughts on what you are experiencing.

-Z

 

[lowwall]

Echoing the above, it sounds like one of your stages is tuned a little aggressively. You should check that the IP for the first stage in question isn't set higher than the others. But it's more likely to be one of your second stages. Swap the second stage from the problem regset to another first reg stage and see if the issue persists.

 

[AKinnunen]

Thank you for your answers.

I always set the intermediate pressure to 9.5-10 bar. When I open the tank valve quickly, the low pressure jumps to at least 15 bar, possibly higher, but I can't measure it. I bought this first stage in 2013 and have had it serviced multiple times without any issues.

I use this regulator for my bailout cylinder with an Abyss second stage (this is my standard setup for all bailout regulators). Yesterday, I tested this unit at 60 meters depth, and it worked perfectly except for the overpressure issue. For some reason, this first stage reacts "slowly". When I return home in a few weeks, I plan to mix parts and find the problem. I will also check the second stage, which works very well, actually, I never thought that it would be a problem, but good to check.

Br: Arto

 

[Zef]

Thank you for your answers.

I always set the intermediate pressure to 9.5-10 bar. When I open the tank valve quickly, the low pressure jumps to at least 15 bar, possibly higher, but I can't measure it. I bought this first stage in 2013 and have had it serviced multiple times without any issues.

I use this regulator for my bailout cylinder with an Abyss second stage (this is my standard setup for all bailout regulators). Yesterday, I tested this unit at 60 meters depth, and it worked perfectly except for the overpressure issue. For some reason, this first stage reacts "slowly". When I return home in a few weeks, I plan to mix parts and find the problem. I will also check the second stage, which works very well, actually, I never thought that it would be a problem, but good to check.

Br: Arto

I take it you "can't measure it" because your IP gauge maxes out at 15Bar, correct?

15Bar is already quite a bit high.

How does your IP gauge respond when you use it to check your setup? When hitting the 2nd stage purge button, does the IP immediately lockup at the pressure you set it at? or does it creep higher before locking up?

You might have a bad o-ring or 2 in your 1st stage, or an issue with the poppet, orifice or both.

-Z