Water in SPG

[SlugLife]

I've had water in one of my SPGs before, it mostly just made it harder to read, but otherwise worked fine.

 

[Bob DBF]

Question: if you were on a foreign dive trip and this happened on day one of 8 would keep using it if you couldn’t find a replacement?

Yes. Regardless of water in or oil out, it is a case o-ring failure, the bourdon tube will not be affected. What I would do should not be considered to be best practices. What I do is based on my knowledge of the gear, the dive, and what I know I can get away with.

 

[TetronarceCalifornica]

I don't think water got in. I think oil got out.

Update: I sent the photo of the liquid SPG to the Italian manufacturer, Termo. I asked if they could tell from the photo of the liquid was water or oil. They responded that it is definitely water from leakage.

The oil theory has been defeated.

 

[johndiver999]

Saltwater in a pressure gauge will cause failure, in a few weeks or month. The corrosion will cause the needle to stick or fall off - I have seen it too many times. It may be instantaneous if the water got in there on the last trip, even a few drops and you did not notice it. Buddy's failed like that a few weeks ago in fact, needle only moved to 750 psi - on a full tank.

Playing games with a gauge that you know is compromised is unwise if you care how much gas you have in the tank.

 

[DiveGearExpress]

Mineral oil is placed in some types of gauge housings to dampen the needle movement due to vibration where the gauge is mounted in a panel on machinery that vibrates (for example, compressors). Submersible pressure gauges used in diving do not require dampening and thus I've never seen a oil filled SPG intended for use in SCUBA applications. Certainly no SPG we sell has ever been oil filled, although some of our analog transfill hose gauges have been oil filled. If you see something sloshing around in the housing of the SPG on your SCUBA regulator, then it's water.

Should the bourdon tube inside the SPG body crack (very rare in modern gauges, but does happen) releasing the tank pressure directly in to the housing then absence of any form of over pressure relief could cause the housing to literally explode in to shrapnel or at least the glass/plastic face to be ejected with tremendous force. Properly designed modern SPG housings contain a rubber "blowout" plug in the back or side of the body as a safety device. The rubber blowout plug serves to relieve the abnormal pressure inside the housing created by the failure of the bourdon tube. In theory, once the tube cracks and the blowout plug is ejected, the housing could flood if subsequently submerged. However the SPG itself would not indicate pressure and leak gas and if submerged would bubble furiously out the opening created by the now absent blowout plug. In practice we've sold thousands of these "brass & glass" gauges manufactured by Termo Industria of Italy and we've never had one returned where the tube had cracked and the plug was ejected.

So how does water get inside the forged metal housing if the SPG inself is still properly indicating pressure? There are several different causes: (1) The rubber blowout plug itself or the oring seal between the glass face and body leaks or becomes dislodged from severe impact. (2) The glass face is cracked due to impact. Most (but not all) of the water filled SPGs we inspect show signs of impact on the back or side of the body. (3) However impact is not the only cause of floods... a less common cause is thermal shock to the blowout plug and/or o-ring face seals - allowing the SPG to get very very hot from direct exposure to the sun between the time the regulator is mounted and pressurized, then jumping in to the relatively cool water. (4) Although very rare, either the O-ring or blowout plug are not properly sealing from the factory - in which case the SPG floods with initial or early use. [Note this discussion applies to the Termo brand "brass & glass" metal housing, the PPS sourced SPG (Oceanic, et al) SPG has a plastic housing that itself can also be cracked from impact and leak.]

The water, even sea water, does not immediately affect the operation of the SPG in the short term and the SPG can continue to be used if required to "save-a-dive"; but the SPG must be replaced as the moisture inside the case will cause corrosion of the mechanism and subsequent failure.

 

[TetronarceCalifornica]

Mineral oil is placed in some types of gauge housings to dampen the needle movement due to vibration where the gauge is mounted in a panel on machinery that vibrates (for example, compressors). Submersible pressure gauges used in diving do not require dampening and thus I've never seen a oil filled SPG intended for use in SCUBA applications. Certainly no SPG we sell has ever been oil filled, although some of our analog transfill hose gauges have been oil filled. If you see something sloshing around in the housing of the SPG on your SCUBA regulator, then it's water.

Should the bourdon tube inside the SPG body crack (very rare in modern gauges, but does happen) releasing the tank pressure directly in to the housing then absence of any form of over pressure relief could cause the housing to literally explode in to shrapnel or at least the glass/plastic face to be ejected with tremendous force. Properly designed modern SPG housings contain a rubber "blowout" plug in the back or side of the body as a safety device. The rubber blowout plug serves to relieve the abnormal pressure inside the housing created by the failure of the bourdon tube. In theory, once the tube cracks and the blowout plug is ejected, the housing could flood if subsequently submerged. However the SPG itself would not indicate pressure and leak gas and if submerged would bubble furiously out the opening created by the now absent blowout plug. In practice we've sold thousands of these "brass & glass" gauges manufactured by Termo Industria of Italy and we've never had one returned where the tube had cracked and the plug was ejected.

So how does water get inside the forged metal housing if the SPG inself is still properly indicating pressure? There are several different causes: (1) The rubber blowout plug itself or the oring seal between the glass face and body leaks or becomes dislodged from severe impact. (2) The glass face is cracked due to impact. Most (but not all) of the water filled SPGs we inspect show signs of impact on the back or side of the body. (3) However impact is not the only cause of floods... a less common cause is thermal shock to the blowout plug and/or o-ring face seals - allowing the SPG to get very very hot from direct exposure to the sun between the time the regulator is mounted and pressurized, then jumping in to the relatively cool water. (4) Although very rare, either the O-ring or blowout plug are not properly sealing from the factory - in which case the SPG floods with initial or early use. [Note this discussion applies to the Termo brand "brass & glass" metal housing, the PPS sourced SPG (Oceanic, et al) SPG has a plastic housing that itself can also be cracked from impact and leak.]

The water, even sea water, does not immediately affect the operation of the SPG in the short term and the SPG can continue to be used if required to "save-a-dive"; but the SPG must be replaced as the moisture inside the case will cause corrosion of the mechanism and subsequent failure.

I want to give two thumbs up for DGX response and how they handle their warranty. Great company.

 

[happy-diver]

 

[DiveGearExpress]

Drifting now... Glycerine is mostly used today as the liquid dampener in gauges but in panel mounts on compressors where the gauges are going to be mounted where they will be exposed to heat I prefer mineral oil. The two are not miscible... if you are topping off and uncertain what it is, check by taking a drop of the existing fluid from the gauge and seeing if it mixes with water... if so it's glycerine, if not it's oil. FYI, if the needle doesn't seem to need vibration dampening then there is little benefit and it's probably best not to use either.

 

[billgraham]

As a sidemount or CCR diver with sidemounted bailouts, I've broken a dozen of these. Toss it.

 

[mr_v]

I had the same issue happen to the same brand SPG.

The gauge will function, but I did not feel like diving with a know backup, so I replaced it. If you travel or are on a budget, consider buying a few button gauges as quick replacements. I get my from Piranha for $15:

https://www.piranhadivemfg.com/category/Pony-Bottle-Gauges-310

These work very well!