Considering a used reg. Which should I *not* consider?

[kroorda]

Based on my own, as well as many other peoples' experiences, I would not own a piston type regulator. The reason is that they tend to be, or get noisy underwater. They require much more maintenance than a balanced diaphram regulator does.

 

[halocline]

Based on my own, as well as many other peoples' experiences, I would not own a piston type regulator. The reason is that they tend to be, or get noisy underwater. They require much more maintenance than a balanced diaphram regulator does.

This is not true. You need a better service tech, and it's simply false that piston regs require "much more" maintenance than diaphragm. In fact, flow-by pistons require almost no maintenance, typically can go years between servicing, and the simple ones have 2 o-rings and one moving part. Flow through do have the HP o-ring which is subject to high pressure gradients, but the best of these are dirt simple and very long-lived.

 

[DA Aquamaster]

My thoughts when I read the "noise" thing was "oh...he may have encountered a less than stellar tech".

That's not entirely fair as in some rare cases you can have a rough/scored piston stem that will vibrate (which is then heard as a high pirched whistling sound) that may not present itself for a few dives post service. And in some very old and well worn flow through piston first stages, excessive tolerances between the piston and reg body along with high pressure tanks in the 3500-3600 psi range can cause pinching of the HP o-ring, which over the course of several dives can then can be rough and start causing the piston to vibrate.

But in most cases, the whistling is due to inadequate initial lubrication of the piston stem o-ring and that is a tech issue.

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You could argue that a diaphragm reg ages better or lasts longer, but that's a hard argument to make given that some piston regs like the Mk 5 have been around since the late 1960s and in many cases have been updated with 4 or 5 port turrets, keeping them viable that whole time. In comparison, diaphragm regs like the Conshelf 11, 12, 14 and later models have been around almost as long, but the older 11 and 12 are now seldom used as they lack a sufficent number of LP ports. Which means the Mk 14s that may have seen continous use are all a decade younger than some of the oldest Mk 5s that are encountered.

One of the shops I work still has Mk 5s in rental and while some of them have bene retired over the last few years, they have seen long, hard use over a nearly 40 year career and I doubt any reg design woudl have done better.

Which is to say: 1) it's not the age, its the mileage and 2) any qualitative differences in longevity between piston and diaphragm regs will be lost in the noise of differences in use, maintenence and number of breathing cycles.

 

[scubafanatic]

Based on my own, as well as many other peoples' experiences, I would not own a piston type regulator. The reason is that they tend to be, or get noisy underwater. They require much more maintenance than a balanced diaphram regulator does.

While most of my regs are diaphragm 1st stages (Poseidon/Apeks/Mares/Aqualung) I also own 2 'piston' Atomics (M1 and T2) and I've never had any problems with my Atomics, they're wonderful regs! Mine have the Cristolube filled dry 1st stages, which may be one reason I've never had issues with them (the lube keeps everything lubricated and keeps crud outside of the 1st-stage) Really the only downside is the extra expense of the Cristolube during 'annual' servicing, which diaphragm regs don't have to deal with.

 

[Hatul]

Skip the Oceanic Delta 2, and I agree skip Mares, it's just a bad company with bad customer support.

Adam

 

[hijax]

Really surprised to hear the comments about Mares. Always assumed they were top-notch just based on the perceived influence in the diving world.

 

[DA Aquamaster]

Mares makes good regs, they just have a poor track record for supporting them over the long term, and they have some odd, and very European service practices where seats, etc, get reused rather than replaced annually.

 

[Eric Sedletzky]

Mares makes good regs, they just have a poor track record for supporting them over the long term, and they have some odd, and very European service practices where seats, etc, get reused rather than replaced annually.

Are those seats the type that can be flipped for a new surface or are they just being cheap?

 

[LeadTurn_SD]

Are those seats the type that can be flipped for a new surface or are they just being cheap?

1.) The HP poppet is a 2 year part. It is removed and inspected at annual service; if in good shape the tech "scores" a "1" on the back surface to indicate it was reused once already. At the next service the tech will "see" the "1", know the HP poppet was re-used once, and change it.

2.) The 1st stage diaphragm is also reused if "ok".

3.) All other soft parts for the first and 2nd stages and hoses are included in the annual rebuild kits I have, even including 2nd stage exhaust valves.

There are fewer parts in the Mares rebuild kits compared to other diaphragm regs.... because there are fewer parts? I would like to see the HP poppet and diaphragm in the kits, since at service it makes sense to just replace these parts (since the reg is fully stripped down already).

Best wishes.

 

[halocline]

I'm not sure it makes sense to automatically replace the diaphragm every year as long as it can be re-installed leak free, but it definitely makes sense to replace the HP poppet (or seat on a piston 1st). Those parts get imprinted with the orifice edge, and re-installing them IME usually results in some IP creep due to the orifice not meeting the seat in exactly the same spot, and you end up with overlapping circular imprints.