Exploding SPG gauge faces?

[MikkelBC]

I've heard anecdotal stories of exploding gauges and the need for pointing them way from us while pressuring the octopus.

I've seen a gauge face pop once, it fluttered away without any apparent risk or even a significant disturbance. Was from the '70's. Also seen a button gauge face fail, once again, fairly gentle explosion and would seem horribly unlikely to be hurt by. (intentional irony in gentle explosion, the plastic face flew a couple feet)

Why are we traumatizing new divers with this titbit of task loading? Anyone seen one or read of one going off in a way that might cause injury in recent years? (at least more injury than any other hose failure.)

Regards,
Cameron

I also teach my students that they should not point the SPG at their face while opening the tank. I think it makes a lot of sense, because if not, a lot of people will choose to look directly at the SPG while opening in order to see the pressure in the tank. Even a 'gentle explosion' can cause severe damage to an eye if it is looking directly at it from a short distance.

 

[TMHeimer]

What is a CD?

It all began with the introduction of the Mar Mac SPG in the 1950s
Certainly SOME ONE can guess why it was recommended that the SPG was turned away or shielded by a cupped hand

The Mar Mac had three distinct problems associated with it

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SDM

PADI Course Director

 

[Sam Miller III]

Once again why was the Mar Mac subject to exploding ?

It all began with the introduction of the Mar Mac SPG in the 1950s

Certainly SOME ONE can make a guesstamate why it was recommended that the SPG was turned away or shielded by a cupped hand

The Mar Mac had three distinct problems associated with it
(one was it would blow out when the air was turned on - Why? )
(Perhaps ask your fuzzy faced Instructor or Shop owner)
1
2
3
SDM

 

[Colliam7]

Why are we traumatizing new divers with this titbit of task loading? Anyone seen one or read of one going off in a way that might cause injury in recent years?

Several years ago, I was on a dive boat off the NC coast, motoring to the second site of a two-tank charter. It was a hot, sunny day, and the 10+ divers were sitting forward, in the shade of the upper deck. There was a loud 'bang' and a second noise immediately afterward, when the face of a SPG blew off a (pressurized) reg on a cylinder of the port side at the stern, and slammed into a rig on the starboard side, then richoceted off and ended up on the deck. The force of the 'explosion' was pretty impressive. We generally agreed that, had it hit someone, it would have definitely caused injury.

I have students check the depressurized position of the SPG needle, then turn the face of the SPG away when they pressurize the reg. I honestly don't think this adds any particular task loading. And, after my one experience, I think it is a reasonable precaution.

 

[Sam Miller III]

@Colliam7
Several years ago, I was on a dive boat off the NC coast, motoring to the second site of a two-tank charter. It was a hot, sunny day, and the 10+ divers were sitting forward, in the shade of the upper deck. There was a loud 'bang' and a second noise immediately afterward, when the face of a SPG blew off a (pressurized) reg on a cylinder of the port side at the stern, and slammed into a rig on the starboard side, then richoceted off and ended up on the deck. The force of the 'explosion' was pretty impressive. We generally agreed that, had it hit someone, it would have definitely caused injury.

I have students check the depressurized position of the SPG needle, then turn the face of the SPG away when they pressurize the reg. I honestly don't think this adds any particular task loading. And, after my one experience, I think it is a reasonable precaution.
~~~~~~~~~~~~~~
I have never experienced or heard of an exploding SPG face since Mar Mac ceased production of their units and modern SPGs appeared in the market place.

It is well known that Kalifornia sun is bright and shines from sun up to sun down 24X7 365 days a year, It is also known that it never get excessively hot in dear old Kalifornia-- and of course according to the song "It never rains in SoCal" I have on many occasions dove in very sunny and extremely HOT Baja and mainland Mexico where the roads are bumpy or non existent and never experienced a SPG problem

Why do you suspect the SPG exploded on the boar that you were on ? Heat ? Motion? Age? Usage?

And while you are at it you are an experienced diver who religiously post so what is your best guess on the following:

The Mar Mac had three distinct problems associated with it
(one was it would blow out when the air was turned on - Why? )
(Perhaps ask your fuzzy faced Instructor or Shop owner)
1
2
3
Cheers from California where it all began and where Mar Mac, the first SPG was produced

SDM

 

[Akimbo]

... I have students check the depressurized position of the SPG needle, then turn the face of the SPG away when they pressurize the reg. I honestly don't think this adds any particular task loading. And, after my one experience, I think it is a reasonable precaution.

Interesting. Did you notice if there was a blowout plug in it? I just re-checked all the metal and plastic SPG housings I have, some of which are over 30 years old. They all have rubber-like blowout plugs. It is crazy not to have them but I don't know if there are any industrial safety regulations that mandate them. Most industrial gauges are not gas tight, except for Glycerin filled.

An exploding plastic SPG would be really dangerous because the plastic would shatter and create Shrapnel projectiles in every direction.

 

[DerekR]

Strange how archaic actions are continued in training, without current merit, simply because we've always done it that way. Since it is far more common for an SPG to have a blow-out plug than not, if you actually suffer a catastrophic failure, the back of the SPG becomes the dangerous side - not the face. To point the face away from yourself puts you at more risk of being hit by a flying plug. Check your equipment regularly and it won'y matter which direction the SPG is facing.

 

[Akimbo]

Strange how archaic actions are continued in training...

That is the risk whenever someone tries to condense a concept into a rule. "Never do X because..." is a learning experience, is likely to be remembered, and properly applied. "Never do X." is lazy and perpetuates myths.

 

[divad]

Check your equipment regularly and it won'y matter which direction the SPG is facing.

How do you check for a leaking Bourdon tube?

 

[Pinecube]

Certainly SOME ONE can make a guesstamate why it was recommended that the SPG was turned away or shielded by a cupped hand

The Mar Mac had three distinct problems associated with it
(one was it would blow out when the air was turned on - Why? )
(Perhaps ask your fuzzy faced Instructor or Shop owner)
1
2
3
SDM

I'll take a whack at it...
1) No pressure relief/blowout
2) Regs used to have larger openings in the HP ports causing more air to hit the SPG at once.
3) Materials that didn't account for temperature. Becoming too brittle in the cold or more malleable in the heat... Or maybe just a case of materials contracting/expanding at different rates causing issues between the lens and the case?

It wouldn't be the first time a product from California didn't account for the weather elsewhere in the world. Are Tesla's still shipped to with windshield washing fluid only rated to 0F?