SPG or AI, Who’s Right?

[Littlerayray]

I dive with two transmitters and two computers. They always appear to agree. I don't trust a mechanical pressure gauge. They were good when there was no alternative. Why do people hold them away from themselves when turning a tank on? Just askin' ...

This was an old practice because if there was unseen damage the lens could now up now there is a pressure relief valve on the back and you shouldn't turn the face away from you as this would cause the burst plug to shoot towards you

 

[hroark2112]

This was an old practice because if there was unseen damage the lens could now up now there is a pressure relief valve on the back and you shouldn't turn the face away from you as this would cause the burst plug to shoot towards you

I carry an explosion-proof chamber at all times and turn on my SPG inside that.

Safety First!!!

 

[txgoose]

Just this past weekend, wasting time, I checked six gauges on the same tank. A Mares at ~2750, an Oceanic at ~2900+, an Oceanic at ~3100-, a Tusa at ~2900, an XS Scuba at ~2850, and a Genesis at ~2850. I am interested in testing them again closer to the magic 500psi. I have no experience with AI to speculate on how six transmitters might do in the same test.

(EDIT: The last two frames are of the first two gauges, simply to show no appreciable pressure drop from the testing.)

Six_guages_six_pressure_readings

• txgoose
• May 2, 2018

Six gauges and six pressure readings. The last two frames are just to show no measurable (with...

 

[MXGratefulDiver]

^^^^^ ... what he said

I own several reg sets, and have done the same experiment to see how my gauges would read. There was a roughly 300 psi difference between the highest and lowest reading. Mechanical gauges are notoriously inaccurate.

To answer the OP ... go with the lowest reading. You'd rather come back with an extra 10 bar than to find yourself at your safety stop when your tank pressure will no longer let you inhale ...

... Bob (Grateful Diver)

 

[caruso]

If the spg is in a boot then you don't need to worry about the release valve shooting out the back and hitting you it would be confined by the boot.

 

[Littlerayray]

If the spg is in a boot then you don't need to worry about the release valve shooting out the back and hitting you it would be confined by the boot.

My boot has a hole and that hole allows that little orange insert to come flying out with whatever pressure is in the bottle

 

[Littlerayray]

There's even a warning to not have that plug covered

 

[divinh]

So if your SPG has a relief plug, then it's best to have the face facing you and the bottom facing against the BC, to absorb a burst? (I was originally taught to hold the face against the BC to prevent glass flying everywhere, in case of bursts.)

 

[caruso]

So if your SPG has a relief plug, then it's best to have the face facing you and the bottom facing against the BC, to absorb a burst?

Yes of course like they posted above, the relief valve pops out the back and if there's a hole in the boot which appears to be the rule, guess where it's going?

I don't know about putting it against the BCD perhaps the pin might damage the bladder but that's just an assumption I'm making.

 

[Littlerayray]

So if your SPG has a relief plug, then it's best to have the face facing you and the bottom facing against the BC, to absorb a burst? (I was originally taught to hold the face against the BC to prevent glass flying everywhere, in case of bursts.)

Yes the glass/plastic face on modern spgs are not meant to burst hence the relief plug I would just hold the spg face towards you and the rear pointed towards the ground