Diving myths taught for safety?

[thorshammer]

Has anyone mentioned turning the SPG away from your face when you turn the tank on? I do it out of habit but in 43 years I've never seen one explode.

I was taught to turn and hold the SPG against the inside of the BC while slowing cracking the valve.

 

[boulderjohn]

I was taught to turn and hold the SPG against the inside of the BC while slowing cracking the valve.

I teach students my own understanding about it, which is that when SPGs were first introduced, there was a problem with some of the glass covers popping off--not an explosion really. I tell them that technology has improved. I tell them I have never heard of it happening, and I doubt that I ever will. Still, it makes sense not to be staring into it as it happens, just in case. Pointing it away at the instant you begin to turn on the gauge, or at the BCD, is a small measure of safety.

 

[thorshammer]

I sort of wonder how applicable this rule is to a flying in a pressurized airplane. Sure the aircraft could have an issue and lose pressurization (all the masks dropping) but if that happens you might have bigger problems to worry about than DCS.

It's there due to the fact that airplane cabins are pressurized from 5000-8000 ft. Not so much in the event of total cabin pressure loss.

 

[TMHeimer]

I learned to have the 2nd stage purge open briefly when turning gas on so the gas has somewhere to go other than right into the SPG.

 

[spoolin01]

So safety stops are mandatory?

Optional.... Mandatory...

That's why I liked it as a myth - the notion of the safety stop as binary variable.

...

Since that original research for the tables, further research indicates that safety stops are more valuable than that early research showed. One study that you will find on the DAN website showed that stops were more important than the ascent rate. Consequently, I will do stops for all but pretty shallow and and short dives. No, I don't have a specific cutoff.

Interesting bit. I figure the message is: the deeper and longer you go, the more that averaging-up the 'area above the curve' is prudent.

 

[Bob DBF]

I teach students my own understanding about it, which is that when SPGs were first introduced, there was a problem with some of the glass covers popping off--not an explosion really. I tell them that technology has improved. I tell them I have never heard of it happening, and I doubt that I ever will. Still, it makes sense not to be staring into it as it happens, just in case. Pointing it away at the instant you begin to turn on the gauge, or at the BCD, is a small measure of safety.

In the event of the bourdon tube failure, 3000# air is released into the gauge. New gauges have a pressure blowout which will relieve the pressure, some older ones didn't. I never had it happen to me, but did have a piece of gauge fly by me back in the late '60's.

It's always a good idea with any HP air, to turn the air on slowly and look away, just in case there is a problem, your eyes will not be involved.


Bob
-------------------------------------
I may be old, but I'm not dead yet.

 

[BDSC]

I'll be at the DAN headquarters next Wednesday when they have their bi-monthly presentation. I'll be sure to get their take on the silent bubble thing. I would assume the studies you have seen on that are most likely from DAN research. This month they are going to talk about your heart condition and diving.

So I was at the DAN meeting last night and spoke with the head researcher for DAN. I asked him about the value of safety stops and had they done research on such. I specifically asked about the "bubbles". His answer was that for deeper recreational dives, no doubt safety stops are a benefit. However, he said if your dive profile is conservative and you are well within you decompression limits (like shallow dives typically), then doing a safety stop has very little benefit as far as helping with "silent bubbles". If there is any benefit in that type of situation it's simply to slow down the diver on their accent.

As a matter of fact he said that most people believe that you "bubble" each time you dive but he said studies show that is not the case at all. On some dives no bubbling occurs. And, of course, it can all vary between different divers and the same diver on different days.

 

[bl6394]

So I was at the DAN meeting last night and spoke with the head researcher for DAN. I asked him about the value of safety stops and had they done research on such. I specifically asked about the "bubbles". His answer was that for deeper recreational dives, no doubt safety stops are a benefit. However, he said if your dive profile is conservative and you are well within you decompression limits (like shallow dives typically), then doing a safety stop has very little benefit as far as helping with "silent bubbles". If there is any benefit in that type of situation it's simply to slow down the diver on their accent.

As a matter of fact he said that most people believe that you "bubble" each time you dive but he said studies show that is not the case at all. On some dives no bubbling occurs. And, of course, it can all vary between different divers and the same diver on different days.

Thanks for following up that. Really nice - all the work that DAN does for the diving community.

 

[BDSC]

Thanks for following up that. Really nice - all the work that DAN does for the diving community.

It's kinda funny. When Neal sees me coming and I say, "I have a question for you", he says "What thread on ScubaBoard is this question about?"

 

[rstora01]

Breath holding or even skip breathing can cause a build up of CO2 in your body, which can lead to bad headaches or worse a blackout.
No body will stop someone if they insist on it but it's not recommended for safety reasons. Why push things to an extreme? Relax and
enjoy yourself.