Question "Bouncy" Submersible Pressure Gauge

[JonnieB]

So I recently replaced a well-used SPG due to it being "bouncy, " i.e. the needle bouncing 20 bar negative on inhalationg and returning to point on exhalation. On the final dive of use, it read a full 210 bar on the surface and after 10 minutes diving was reading 100 bar. (One-hundred bar normally is 40-50 minutes for me.) So I replaced the SPG with a new one. It appears to be functioning normally, but I still get a twenty bar needle bounce per breath cycle, especially when the tank is low. (And yes, both with the new and old SPG, the valve is always open allmthe way.)

Any suggestions on what my be causing this? Could it possibly be the valve itself,, or some problem with the HP port of the first stage? Thank you for any advice or suggestions.

 

[rongoodman]

Try the SPG on a different regulator and see how it does? I've never seen one do anything like that.

 

[johndiver999]

You probably want to remove the hose from the first stage and then clean and or check the tiny hole in the first stage and the upstream end of the hose. A tiny piece of salt or corrosion can partially block the little holes

 

[MarkA]

What is between the air in the cylinder and the SPG. And what could cause the SPG to drop by approx 20 bar during a breath.

Between the high pressure air in the cylinder and the high pressure air in the first stage there is the cylinder valve, the filter and any version of auto closure. I have seen an SPG drop during a breath when the cylinder valve was only opened 1/2 turn (try a different cylinder). There are threads on this board showing blocked filters causing issues and the auto closure causing issues. Also some weird ones where other things blocked the gas path.

If the restriction was between the high pressure area in the first stage and the SPG (e.g. blocked little hole). It is unlikely the SPG would register a drop during a breath.

A good reason for 2 good breaths before entering the water looking at the SPG not to move.

 

[Johnoly]

"bouncy, "

Kinda like the sticky compass needle. There you are headed the wrong direction for several minutes til it spins 90 degrees, self corrects and now you are off course.

Open trash lid, throw it in as hard as you can for it's final bounce, open DGX(?) website & order.

 

[lexvil]

Kinda like the sticky compass needle. There you are headed the wrong direction for several minutes til it spins 90 degrees, self corrects and now you are off course.

Open trash lid, throw it in as hard as you can for it's final bounce, open DGX(?) website & order.

Then check the air path.

 

[Subcooled]

So I recently replaced a well-used SPG due to it being "bouncy, " i.e. the needle bouncing 20 bar negative on inhalationg and returning to point on exhalation.

Sounds like restricted air flow. Something is clogged. Did you properly open the tank valve? If this happens with your new SPG too, check the 1st stage.

 

[grantmac]

Regulator problem

 

[JonnieB]

What is between the air in the cylinder and the SPG. And what could cause the SPG to drop by approx 20 bar during a breath.

Between the high pressure air in the cylinder and the high pressure air in the first stage there is the cylinder valve, the filter and any version of auto closure. I have seen an SPG drop during a breath when the cylinder valve was only opened 1/2 turn (try a different cylinder). There are threads on this board showing blocked filters causing issues and the auto closure causing issues. Also some weird ones where other things blocked the gas path.

If the restriction was between the high pressure area in the first stage and the SPG (e.g. blocked little hole). It is unlikely the SPG would register a drop during a breath.

A good reason for 2 good breaths before entering the water looking at the SPG not to move.

I'll have a look at the filter; it's an Aqualung reg so does have ACD. The SPG needle doesn't really bounce with a full cylinder - usually towards the last quarter of the dive when cylinder pressure is low.

 

[JonnieB]

Kinda like the sticky compass needle. There you are headed the wrong direction for several minutes til it spins 90 degrees, self corrects and now you are off course.

Open trash lid, throw it in as hard as you can for it's final bounce, open DGX(?) website & order.

I did buy a new SPG but still bouncing 5-10 bar at the end of a dive, when tank pressure is low. Will try it on a different first stage.