One SPG only..?

VeniVidi · Oct 4, 2004

Dear all,

As far as I have learned, there is only one submersible pressure gauge (on the left hand side) required in a DIR configuration.
Can anybody explain me why redundancy is not applicable for SPGs since they deliver the most vital information a diver requires? I am thinking of the emergency case when one has to shut off the left tank and abort dive with the right tank. Then there is nothing one can control the residual gas supply.

I have never understood this concept for why I always dive with two SPGs. If someone can tell me if I there is a misconception from my side, I would be grateful for anybody who is (cap)able to illuminate me...

Rubis · Oct 4, 2004

Some questions for you :

1) What do you think is the primary pressure control system you have ?

2) What are you going to do when you have a failure on the left post ? Are you going to go on with your dive ? Do you dive solo ? How do you manage your gas ?

Boogie711 · Oct 4, 2004

What Rubis is getting at, just in case she's being too cryptic:

Your SPG IS your backup pressure gauge. Your primary pressure gauge is your brain. DIR is about mental awareness - you know your breathing rates, and you know your depth and average depth up until that point in the dive, right? So therefore you should know how much gas you have before you even look at the gauge anyway.

Secondly, if your gauge DOES die (due to a left post shutdown or anything else) the dive is over. Knowing the amount of gas doesn't change anything - you still follow the same deco pattern, since you will be carrying enough gas for your dive, plus enough gas for a friend/emergencies. Since that doesn't change, there's no reason to know how much gas you have remaining. The only answer that matters is "enough."

Therefore, the second SPG is completely unnecessary.

The Kraken · Oct 4, 2004

How about determining your depth for you decompression stage?

VeniVidi · Oct 4, 2004

Rubis:
Some questions for you :

1) What do you think is the primary pressure control system you have ?

2) What are you going to do when you have a failure on the left post ? Are you going to go on with your dive ? Do you dive solo ? How do you manage your gas ?

Hi Rubis

Thanks for your swift reply. Now I am a little bit confused as the questions you addressed are exactly those I want to get answered. Maybe I do not understand what you are exactly up to so I answer your questions as follows:

1) The primary pressure control system being the left-handed SPG, whereas the right-handed one representing the back-up. In my case I check up both regularly, also in order to detect some potential failure of any of the two SPGs.

2) If there was a failure on any of both side I would abort the dive. Now gas management is outlayed with the "rule of thirds", especially when diving solo.

If you need more details, let me know.

jonnythan · Oct 4, 2004

Boogie answered the question well.. I'm not sure why you brought up solo diving, though.

VeniVidi · Oct 4, 2004

The Kracken:
How about determining your depth for you decompression stage?

Hi Kracken

Maybe there is a misunderstanding: The question has nothing to do with the depth gauge (var. depth meter) but with the residual pressure in your tank(s).

Rubis · Oct 4, 2004

VeniVidi:
Hi Rubis

Thanks for your swift reply. Now I am a little bit confused as the questions you addressed are exactly those I want to get answered. Maybe I do not understand what you are exactly up to so I answer your questions as follows:

1) The primary pressure control system being the left-handed SPG, whereas the right-handed one representing the back-up. In my case I check up both regularly, also in order to detect some potential failure of any of the two SPGs.

2) If there was a failure on any of both side I would abort the dive. Now gas management is outlayed with the "rule of thirds", especially when diving solo.

If you need more details, let me know.

Boogie answered the questions. And another hint for 1) was : all back-up equipement is on the left. SPG is on the left.

And solo is not DIR. Again Boogie answered your question

The Kraken · Oct 4, 2004

Never mind . . . I had a brain fart.
It's Monday. It's Morning. Nuff said . . . .

novadiver · Oct 4, 2004

VeniVidi:
Dear all,

As far as I have learned, there is only one submersible pressure gauge (on the left hand side) required in a DIR configuration.
Can anybody explain me why redundancy is not applicable for SPGs since they deliver the most vital information a diver requires? I am thinking of the emergency case when one has to shut off the left tank and abort dive with the right tank. Then there is nothing one can control the residual gas supply.

I have never understood this concept for why I always dive with two SPGs. If someone can tell me if I there is a misconception from my side, I would be grateful for anybody who is (cap)able to illuminate me...

I'm not DIR but I only use the one pressure gauge (on the left post) because if there is a left post shut down I go to emergency procedure and turn off that post . after that it's all knowing my SAC rate and looking at my watch. and depending on the problem you can turn the left post back on to see if the problem has cleared ( freeze up only)

One SPG only..?

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