Does this really ever happen? How often has /does a regulator actually fail?

[Luis H]

I suspect that as time goes well past skipping a recommend service interval, your risk of failure goes up. Then again, it seems like shortly after servicing, your failure risk goes up a good deal. Wonder where the sweet spot is?

Richard.

Typical failure rate distribution.

The typical statistical failure rate follows a curve that we call (in engineering) a bath tub distribution. Think about the shape of a bath tub. On the far left and the far right the raised walls represent high number of failures. In the center the flat bottom represent very low failure rate.

The large numbers of initial failures is called "infant mortality" and it occurs to new or recently serviced equipment/ machinery. There are a number of reasons for infant mortality on equipment, just a few examples: human error during assembly, new unproven parts, defective new parts, new parts that don't play well together (due to tolerance build up, etc), parts that need to break-in together, and a number of combinations of any of the above.

Once a piece of equipment is working properly and is past the infant mortality period (also called the break in period in some equipment) the failure rate normally drops dramatically (this is typical for most well design equipment/ machinery). This is the reason why, in engineering, we have the saying: "if it ain't broke, don't fix it".

Note: the actual break-in period (or period for potential "infant mortality") varies a lot depending on the type of equipment.

Then at some point the failure rate starts to rise again due to end-of-life types of failures. In the case of pneumatic equipment (like scuba regulators), this types of failures are caused by material degradation (like rubber O-rings and the soft seats). Also normal wear is another typical end-of-life type of failure.

Any of the rubber components, like the exhaust valve, diaphragm, hoses, have a life expectancy that can range from a few years to well over 40 years if stored carefully and properly maintained. But they will decay with exposure as a function of time, and can cause "end-of-life types of failure.

Typical end-of-life type of failure will take many years to occur on pneumatic equipment like regulators, unless there is accidental contamination (from salt water flooding, rust from a tank, etc) or other abuse. Just a few drops of salt water (from not drying the tank valve connection) can accumulate and cause enough corrosion to totally disrupt the normal life expectancy of the regulator.

Note: most end-of-life type of failure can be avoided by monitoring and inspecting the regulator (see: http://www.scubaboard.com/forums/regulators/346813-regulator-inspection-checklist-rev-7-a.html)

The risk of failure normally doesn't go up gradually as a function of time. It normally flattens with a very low rate until materials start to degrade (normally takes a long time). But accidents and poor normal maintenance (cleaning the salt water off) can ruin the failure rate distribution.

The failure rate described above, (what should be typical) can be totally ruined due to a number of accidents caused by human error, etc (like forgetting to use a dust cap and flooding the regulator) or from poor rinsing and fresh water soaking the regulator.


Notice that my discussion did not address the type of failure (minor free flow, versus catastrophic air shot-off, etc) and that in some parts I was trying to describe failure rates as it applies to most generic pneumatic equipment. Scuba regulators are just one type of pneumatic regulator.

 

[Trace Malinowski]

Hey Trace,

I wouldn't refer to those two guys as my buddies! Or, are you trying to be polite?

markm

With any luck I'll never know if this is paranoid or prudent, but I never dive with all recently serviced regs. Whether it's my pony or sidemount, if one was just serviced , the other one has been around for a while.

flots.

Mark,

Those were two of my best friends. Each wanted me to go to the other guy for gas. That was at the height of my freediving career so they figured I was good for a while. It did make funny video. One guy clearly was like "But, I have the reel. The reel is important. Get Chris to stop filming." Chris was signaling, "I know. I know. Go to Tobias. This is great footage!"

Flots,

You are absolutely right. In fact, it's even good practice to cave dive with completely different makes and models of regulators according to the old-timers just in case an idiot serviced both incorrectly. Different brands often are not done at the same place. But, like you pointed out you always want to dive with one that you know works. I was going to dive with one Dive Rite that I knew worked and the recently serviced Zeagle. But, Chris didn't want to mess with the feng shui of two matching regulators for video aesthetics. He promised me that he gave me the best rebuilds EVER! Not.

I forgot that I needed to unscrew the 2nd stage cover and reseat a diaphragm once. I was diving with several recreational divers all of whom swam away as I worked on it. This after I showed them I was taking it apart and what I was doing. They were like, "Cool! That's what a 2nd stage looks like! Thanks! Toodles!"

 

[kensuf]

I've seen people think they were out of air because their valves were not open all the way. Perfectly functioning and well maintained reg, just the k valve was only open 1/4 turn. There was even a fatality last fall here in Florida because a diver thought he was out of air (1/4 turn).

IMHO, this is an example of why your valves should be open all the way...

 

[Luis H]

I suspect that as time goes well past skipping a recommend service interval, your risk of failure goes up. Then again, it seems like shortly after servicing, your failure risk goes up a good deal. Wonder where the sweet spot is?

Richard.

In reference to the "recommended service interval".

I should add that I have not seen any evidence that the "recommended service interval" has much if any technical merit (but there is one possible exception).

In other threads, there has been a lot mentioned about the financial incentive (to the dive shops and therefore the manufacturers) of the frequent service intervals, so I don't need to repeat it here.

The only exception to why the yearly or biannual could have some technical merit is if the manufacturers are trying to be proactive about poor regulator care (from the diver) and possible human (diver) error during the regular cleaning of salt water, etc. This exception is a bit of a stretch, but I am giving the manufacturers the benefit of the doubt.

If a diver takes good care of his/ her regulator (good cleaning, not allowing to get salt water inside, etc), there is no technical reason why a regulator would need to be torn apart every couple of years.

The "recommended service interval" goes against the principle of: "if it ain't broke, don't fix it".

Note: I do not service any of my regulators based on an arbitrary time interval. I service them exclusively based on what we refer to OQE (Objective Quality Evidence). OQE can be any observable or measured physical evidence of the status of the equipment. In this case can be any visible evidence of corrosion, IP drift, dirt in the intake filter, minor leaks, etc.

I check my regulator on a regular basis and before every dive. I often check for leaks by pressurizing the regulator and closing the tank valve. If the pressure drops (even in a 24 hour period) there is a leak. If the leak is very small I may not do anything about it at the moment, but I keep track of it.

---------- Post added June 22nd, 2014 at 07:55 AM ----------

I should add, that I can only remember one regulator failure of my own (free-flow under the ice), but then again I was pushing the limits while experimenting and I wasn't as careful as I should have been.

 

[markmud]

Hey Luis,

Your post #34 is right-on.

I follow some of the same protocols as you. Your OQE regimen is perfect.

Two things that I do that is different from the industry standard are:
1) I soak my regs in fresh water while under pressure. They are never hosed off---and they are never dunked in water without the system being pressurized.
2) Before a tank switch or refill procedure, my tank valve and first stage are rinsed with fresh water.

Every time a tank is changed or filled directly after a dive, the mating surfaces between the first stage and tank valve is covered with salt water. Some of that water will migrate into the "pressure side" of the mating surface and then that droplet of salt water will migrate through your entire regulator system.

I soak my regs underwater while under pressure to avoid water infiltrating through the second stages (reverse flow infiltration). And, as I have seen before, to avoid accidently soaking the reg with the dust cap off.

I also do the valve-turned-off leak down test as you described; however, I plug an IP gauge to my inflator hose to get a faster indication of a leak-down issue.

The results:

Dolphin SCUBA in Sacramento performs my service work. I have them perform a reg inspection and function test every year and an overhaul every 2 to 3 years. During the function and corrosion inspection, they take apart a few hoses, and they remove the cintered filter to inspect for signs of water intrusion or other FOD. It should be noted that we dive between 10 days (my wife) and 25 days per year. We don't use our equipment on a daily basis. We have not had corrosion issues inside our 5 regulators. They have been spotless.

Am I overthinking the contamination threat to my regs? Probably.

I was instructed to clean regulators under pressure by a charter boat captain who took my wife and I to Oriskany. He is also an instructor and a former military diver.

markm

---------- Post added June 22nd, 2014 at 10:12 AM ----------

Hey Luis (for the second time this morning),

I just read your post #31. Very good read.

My dad was a fighter pilot (Fly Navy). When I was a kid, he was showing me some new F-8 Crusader jets that his squadron had received. I asked if the skipper had given him one of the new planes. He told me he refused to fly them for the reasons that you described in your post #31. He also swore that he would never fly in a brand new or newly rebuilt helo for the same reasons. He likes an a/c that has a proven track record for reliability and its OQE record was properly documented (aka: inspections).

markm

 

[tr3a]

How often has /does a regulator actually fail?

Not talking about an out of air situation.

I'm talking a situation where you have plenty of air in your tank and you simply can not breathe off your reg.

Also to expand on this, how many of these regs were actually maintained properly?


Yes, Cozumel -- rental AL tanks had standing water inside. After inverting (head down vertical) first stage was completely choked off with wet AL oxide sludge. 2000 psi in cyl. Regulators well kept & serviced (new filters just prior to trip)
Rental cylinders on location, who knows

 

[KevinG58]

At the surface back swimming out from shore while shore diving in Bonaire, my main dive buddy had the 2nd stage come off the hose, resulting in some gas lost. Since we were at the surface, not a big deal; kind of interesting watching the ocean boil for a moment there.

Underwater, could've been bad news.

I think it had just recently been serviced.

Richard.

Mine blew off during initial setup of the rig for the day, but I had dived it the day before. Cause for much introspection on the meaning of life and review of maintenance practices and pre-dive checks. No one to blame but myself as I was the last to touch it when I swapped out the LP hose.

 

[randy88k5]

Back in the '80s, my father had his Tekna regulator fail to deliver air at depth, twice. Both times he had two independent first stages, and was able to switch to the alternate.

It was unclear if it was serviced incorrectly or damaged after being serviced.

 

[Rainer]

I've only ever had one issue. Came up to my 70' stop, went to switch to my 50% bottle, and as soon as I pressurized the reg, the second stage fell apart (I'd just used the same reg on a dive two hours before). Basically the front faceplate just blew off. No idea what caused it. Regs were all well maintained. Shared deco gas from 70' to 30', went to backgas, then switched to my O2 bottle at 20'. No big deal and everything was handled admirably in the team.

 

[snowmaker]

I've seen a few regs fail. All in cold water and they all failed open. They all also emptied the divers tank in just a few minutes. Once saw a divers primary start free flowing and then they backup did the same. All these failures expect one where diving in water around 38 degrees. I believe cold water played a major roll in expect one.

With that said I have never had a reg failure myself and overall the number of failures is low compared to the number of dives I've been on.