First Stage Regulator Failure Rates

[Angelo Farina]

I am close to 1500 dives, 99% of them with my thrusted MK5 (4 of them, 2 on my tank, 2 on my wife - she has roughly 100 dives more than me).
So this sums to a total of 6000 reg-dives.
In total we had 7 failures.
5 times O-ring problems, the one between tank and reg (caused by damaged surface on the yoke surface sealing against the O-ring of my oldest MK5).
In the end I did change the whole yoke adapter. I have DIN now...
Once I had the filter clogged by debris coming from the rusty tank.
And two times it was not a real failure, just small bubbles from the holes, signaling the it was time for new O-rings on the piston.
We did always use two first stage on two independent posts, so none of the failures required to end the dive. We did just close the valve of the affected reg and continued with the other.
The only time I had just one reg it was the case of debris clogging the filter..
So if you want a number I would say 1 failure every 1000 reg-dives.
It had been much less if I had DIN connectors, as I have now on thes 4 MK5, which we are still using now.
The oldest was built in 1975, the newer in 1980.
I think that they are quite reliable.
Still we prefer to use two of them on two independent valves.

 

[lexvil]

This is what I have found.

During 2006 to 2015 there were an estimated 306 million recreational dives made by US residents and 563 recreational diving deaths from this population. The fatality rate was 1.8 per million recreational dives.

From: Buzzacott, P; Schiller, D; Crain, J; Denoble, PJ (February 2018). "Epidemiology of morbidity and mortality in US and Canadian recreational scuba diving". Public Health. 155: 62–68.

In 14% of deaths there was a regulator fault reported, and in 1% the regulator was misused. Subsequent testing of the regulators showed that most of the problems were caused by leaks resulting in inhalation of salt water, but in some cases there was excessive breathing resistance following a mechanical dysfunction. In a few cases the regulator failed catastrophically, or the hose burst. The difficulty of breathing from the regulator was often aggravated by other factors such as panic, exhaustion or badly adjusted buoyancy.

From: Edmonds, Carl; Thomas, Bob; McKenzie, Bart; Pennefather, John (2015). "Why divers die", Diving Medicine for Scuba Divers. pp. Chapter 34.

Using that data, I calculated that 0.25 deaths per million rec dives were caused by reg problems. However, they don’t discuss what the reg types were. Hence, my question.

It seems the “data” is anecdotal being based on estimates which are hard to impossible to source (I clicked the link but couldn’t scroll pages) the total deaths may be a hard number but when trying to get percentages based on total number of dives, I have no idea how you can come up with total dive numbers as an estimate and reach hard numbers. It ain’t chemistry with repeatable results. It’s more swag.

 

[tursiops]

I am close to 1500 dives, 99% of them with my thrusted MK5 (4 of them, 2 on my tank, 2 on my wife - she has roughly 100 dives more than me).
So this sums to a total of 6000 reg-dives.
In total we had 7 failures.
5 times O-ring problems, the one between tank and reg (caused by damaged surface on the yoke surface sealing against the O-ring of my oldest MK5).
In the end I did change the whole yoke adapter. I have DIN now...
Once I had the filter clogged by debris coming from the rusty tank.
And two times it was not a real failure, just small bubbles from the holes, signaling the it was time for new O-rings on the piston.
We did always use two first stage on two independent posts, so none of the failures required to end the dive. We did just close the valve of the affected reg and continued with the other.
The only time I had just one reg it was the case of debris clogging the filter..
So if you want a number I would say 1 failure every 1000 reg-dives.
It had been much less if I had DIN connectors, as I have now on thes 4 MK5, which we are still using now.
The oldest was built in 1975, the newer in 1980.
I think that they are quite reliable.
Still we prefer to use two of them on two independent valves.

If I understand you correctly, I would say you had zero first stage failures. The o-rings and the dip tubes are not reg failures, and poor maintenance on the reg is an operator failure.

 

[joewr]

Hi, Angelo,

You wrote: “5 times O-ring problems, the one between tank and reg (caused by damaged surface on the yoke surface sealing against the O-ring of my oldest MK5).”

That’s consistent with what I’ve read—failure due to leakage versus a mechanical failure due to an internal component.

I have 1,689 dives and my wife has somewhat fewer. We have never experienced a reg failure or even seen one.

As regards our equipment, we have it serviced annually by a tech we’ve know for over 20 years.

Thanks for your note.

Joe

 

[joewr]

It seems the “data” is anecdotal being based on estimates which are hard to impossible to source (I clicked the link but couldn’t scroll pages) the total deaths may be a hard number but when trying to get percentages based on total number of dives, I have no idea how you can come up with total dive numbers as an estimate and reach hard numbers. It ain’t chemistry with repeatable results. It’s more swag.

Here is another source that I think you can access:

“DAN collects data on diving fatalities of recreational divers in the US, Canada and diving destinations frequented by US and Canadian divers, compiles case reports, and includes the data in the DAN Annual Diving Report. The DAN data shows a higher fatality rate: Fatality rates of 16.4 deaths per 100,000 persons per year among DAN America members.I’m not certain what conclusion to draw from that!

 

[lexvil]

Here is another source that I think you can access:

“DAN collects data on diving fatalities of recreational divers in the US, Canada and diving destinations frequented by US and Canadian divers, compiles case reports, and includes the data in the DAN Annual Diving Report. The DAN data shows a higher fatality rate: Fatality rates of 16.4 deaths per 100,000 persons per year among DAN America members.I’m not certain what conclusion to draw from that!

View attachment 598980

I don’t think you can get a hard number beyond fatalities but once you attempt to get the “per” it’s all conjecture.

 

[joewr]

There are way too many variables that would need to be tracked to get meaningful data about failures. Such as:

How the regulator was cared for by the user. Exposure to heat, cold, humidity, and chemical vapors between use. Exposure to sand, algae, salt during use. Rinsed appropriately, inadequately, or not at all after use.

How the regulator was serviced. Quality and durability of the rubber parts. Service interval exceeded or not. Service tech used correct size replacement parts and did not scratch or damage metal parts or not. Service tech tuned regulator correctly or not.

I think the only data available that you might find interesting is regarding regulator recalls.

Dive Equipment Recall Info at Scuba.com

That reminds me of an HL Mencken quote:

"For every complex problem there is an answer that is clear, simple, and wrong."

That said, it seems that the data has been collected that indicates reg fail is not a responsible for a majority of dive fatalities (ca. 14%) and that mechanical failure was not the source of reg failure: leakage was.

That’s probably as far as this topic can go.

Joe

 

[Scuba Lawyer]

In 53 years of diving I've personally experienced two reg failures (one 1st stage piston HP seat and one 2nd stage lever getting stuck in the down position on the poppet stem). Other wise they work pretty well.

Statistics and percentages are a funny thing and depend on your point of view. I walked into a dive shop many years ago and before I carried my tank all the way to the back of the store where the fill station was I innocently asked the manager if their compressor was working.

The guy got all pissed off and yelled at me that their compressor was the best there was and it had only been down two days in the past year and that was a very low down-time rate. I calmly looked at the manager and said, look I've only been in this shop to buy air twice in the past year and both times your compressor was down. So, for me, that was a 100% failure rate.

All depends on your perspective.

 

[Bigbella]

In over four decades and thousands of dives, I have, thankfully, had only two non-catastrophic first stage failures (both of which just pissed me off to no end) -- one in water; the other, out. Each stemmed from inept servicing, by a local dive shop, who hasn't since seen a dime from me.

They would have to have known that there were obvious problems, just upon opening a valve; yet told me that they were bagged up and "ready to go."

Both failures resulted from pinched or torn diaphragms. Never any problems with my piston regulators over that same period . . .

 

[Angelo Farina]

If I understand you correctly, I would say you had zero first stage failures. The o-rings and the dip tubes are not reg failures, and poor maintenance on the reg is an operator failure.

No, the O-ring failures were due to the scratched surface on the part of the reg which mates with the O-ring in the valve. So IT IS a regulator failure, which was fixed replacing the part affected.
And it was not the dip tube which was clogged, it was actually the conical filter in syntherised metal inside the reg which was clogged.
Finally the piston O-rings causing small bubbles needed to be replaced earlier than the standard 2-years interval recommended for these regs: this happened only on the two older MK5, those without SPEC, and is due, in my opinion, to sand or silt entering the first stage. Or perhaps to salt crystals, being very difficult to rinse properly the interiors of the first stage. The other two more recent MK5, with their silicon-packed first stage, never suffered of the same problem.