Pressure gauge reliability

[Bigd2722]

The benefit of having a second SPG is not that it allows you to continue a dive in the event of a failure. The benefit is that you can determine when one of the SPGs has failed in a fashion that causes it to falsely indicate more gas than is actually present, because in that case, the two instruments will not agree.

you can have too much of a good thing. A person with one watch always knows the time, a person with two watches is never sure.

 

[AfterDark]

I've only used mech SPGs during my 46 years of diving. I just retired a mechanical SPG last year and replaced it with one of the same type and vintage (that means I bought it used on Ebay). I got 45 years out of the one I retired so I figure another one that was used lightly will take me to my retirement from diving in less than 45 years..
I have a another SPG the same type on a second regulator set I use on my ID's.

The one SPG failure I had didn't cause me to abort the dive because I noticed it during the pre-dive check and switched to my second regulator set. However had I discovered it during the dive I would have continued the dive. After 46 years of diving I know how long a given amount of air will last for me at any rec depth.

AIs, I consider the technology to be too unreliable for my liking. As I've pointed out in past posts, testing computer type technology is what I do for a living. The results of the testing does not encourage me to want to own an AI.

I haven't got a lot of faith in my PDCs either for the same reason.

 

[packrat12]

After a lively debate about whether the SPG will be replaced by a Wireless Air Integrated computers, I am curious how many people have actually experienced failures of either type of gauge. Feel free to post your tales of terror, and keep in mind that this is not scientific and does not necessarily contradict your blind faith in your preferred technology.

One of the problems with this poll is how a failure is recorded. I have had 1 SPG failure where the hose failed. That was in 1000 dives or so. A weekend diver may have 1 failure but in 100 dives or so. They are not the same. Brass and Glass SPGs have been in use in the diving industry since the 1970's or before. I know by the early 1980's they were almost considered standard gear. How many millions of dives have been on a B&G SPG? How many dives have been on wireless AI or AI? I would suspect that a small fraction of the total number of dives. As a result, any poll just asking "Have you had a failure" will be greatly skewed in favor of wireless AI or AI. You will notice that many divers here state that their gauge failed after xx years. Few computers are still in use at even 1/2 the age of some B&G SPGs. Mine, which were relegated to secondary backups in late 2013 were 32 and 24 years old. They are still perfectly functional but I have replaced them, of all things with a wired AI system. My oldest computer is less than 20 years old and was retired in 2013. I have had 2 issues with my new computers before and during a dive. So I guess we can call 2 failures in 20 dives at the time.... Neither caused a dive to be called though, but nor did my SPG as I used a spare hose.

All gear needs to be properly serviced. I suspect that the hoses and o-rings of a SPG are one of the most neglected areas. They just work though. Even from comments I have seen regarding wireless AI from NetDoc, he has a battery replacement schedule that is very intense. This is done to ensure the wireless AI should work properly throughout the dive. This definitely does not follow the KISS principle. It may work for him and others but I would call it out that since he must take extra steps to prevent failures, the gear cannot be called more reliable than a B&G SPG that sits in a box until needed and will function without intervention, even over a period of years.

A short term interruption on AI in recreational diving may not be a dive ending event. It also may indicate a more critical failure which needs to end the dive.... Diver choice here. In a technical dive, even a short term interruption may be a critical failure and the dive should be turned. I would consider any interruption or issue with syncing a failure on wireless AI. I would call any time I cannot get accurate information from my gear a failure. If it cannot follow the KISS principle then it should not be considered reliable. I should not be fighting my gear as I am getting ready to begin my dive.

 

[Edward3c]

In 37 years I've only had one failure, in water, that's when the gauge unscrewed and fell off.

 

[CT-Rich]

I thought this would be a good alternative thread to the Will WAI ever replace the SPG? That discussion had deteriorated into a bit of mud wrestle (I'll admit to participating with a somewhat trollish glee in that thread....)

I have never claimed that this was anything scientific, but it has gotten people to offer experiences more than unfounded opinions. I have a AI integrated console unit myself, which I have mixed feelings about (the strongest one is that it is paid for and therefore remains part of my kit). SPGs are one of the lowest tech components in diving and even if goes through a catastrophic failure will not put a diver in any significant danger. For those that feel it is not ready for prime time, I will grant you that may be true. On the other hand, those that are condemning a bad experience ten years ago may also be unfairly marking it.

Looking at the data collected so far, out of the 40 or so respondents, neither system is free of incidents. And the majority of failures really has had limited impact on actual dives. From what's been posted, I think for most applications it is a wash from a safety perspective and if you are interested in Electronically logging your dives, may provide some interesting data.

 

[Centrals]

The benefit of having a second SPG is not that it allows you to continue a dive in the event of a failure. The benefit is that you can determine when one of the SPGs has failed in a fashion that causes it to falsely indicate more gas than is actually present, because in that case, the two instruments will not agree.

Two is one and one is none
So you use two transmitters in the double as well.

 

[Diving Dubai]

I confess that while I have wireless AI transmitters I still retain my SPG and on my stages have a button spg (as well as A Transmitter)

Overkill? Not really. At first I kept my SPG while "I gained trust" in my AI and then never took it off. I use my conventional SPGS just to check tank pressure while setting up. All my Transmitters are on quick disconnects and short hoses (to stop damage from over zealous boat crews and other divers)

I've used my AI computer long enough to have faith in it, It always syncs and never drops out. The only issue ever was my wife setting her computer to my transmitter. But you can't blame the equipment for that.

 

[Hawkwood]

Had it happen once. My wife's SPG failed while we were diving.

The indicator needle had separated.

We just continued the dive. She was much, much better on air consumption than me, so we just kept closer together, and came back with more showing on my gauge than we might normally have done.

Have zero experience with a AI computer and have no desire. I'm a cheap bastard.

 

[Bigd2722]

I have had a Suunto hoseless AI computer for approximately 15 years. In all that time I have had 2 incidents where it didn't sync. This wasn't a problem, because I had a 2nd matching computer (bought because I was doing a liveaboard in Galapagos) and always had a back up. For the last 2 years, I have carried a b&g unit because while the computers won't seem to die on me, they are getting old. Currently I dive with one computer and the spg. Can's say that either way is better, but I still rely on the Suunto for all the dive log info.

 

[TMHeimer]

My needle got stuck during one dive at 1000 PSI. I knew something was wrong though be it a shallow 20+ foot dive. Got it replaced.