An actual legitimate use for spare air???

[johndiver999]

Wow what kind of SPGs do you use and why do you keep using them?!

The only mech SPG's issue I've had in 50 + years are spool issues, leaking. A 200 psi deviation is manageable and should never cause an alert diver to be low on air.

Maybe you are lucky. I can't count the number of times I have seen a plastic spg leak and allow water into the case. Most recent was a buddy around 5 months ago. It flooded on the first dive and he used it for the remainder of the day.

I (right now) have a aqualung plastic spg that has not leaked, but the needle goes no lower than 200 psi. I use it occasionally and would not loan it out, but it always seems to work over the normal pressure range.

 

[Divin'Papaw]

Maybe you are lucky. I can't count the number of times I have seen a plastic spg leak and allow water into the case.

Plastic SPG?! Do people actually use those things? I’ve only ever used brass and glass SPG. A plastic SPG sounds like an incredibly bad idea right from go. I honestly had no idea they existed.

 

[johndiver999]

I watch my gauges often enough to know if they were ever stuck, but I wouldn't be at 100 feet with 700psi, let alone 200.

You sound very conservative. 700 psi is around 18 cu-ft (I think) in an 80 cu-ft tank. Obviously if 18 is too little,then a spare air would be out of the question for you. I'm curious, what is the minimum pressure you reach before starting an ascent from 100 feet?

It sounds like you are VERY cautious about the possibility of running too low on air. It would never want to criticize someone for using conservative safety protocols.

Do you exercise an equal degree of caution with respect to a response to a catastrophic failure of the regulator - like say a blown LP hose or something? What protocols are implemented for that unlikely occurrence?

 

[johndiver999]

Plastic SPG?! Do people actually use those things? I’ve only ever used brass and glass SPG. A plastic SPG sounds like an incredibly bad idea right from go. I honestly had no idea they existed.

The first three gauges on a quick leisure pro search are all plastic (if you ignore the mini gauge). they are more common and cheaper than the fancy, heavy metal ones.

Scuba Diving Gauges and Compasses - Buy at LeisurePro

 

[Divin'Papaw]

The first three gauges on a quick leisure pro search are all plastic (if you ignore the mini gauge). they are more common and cheaper than the fancy, heavy metal ones.

Scuba Diving Gauges and Compasses - Buy at LeisurePro

Fancy You mean reliable?

When I’ve ever bought on SPG I’ve only ever bought B&G. Since that’s all I buy I’ve never needed to replace one in 15+ years of diving. Given the cost of Scuba why would anyone skimp on an SPG??? I mean really?? The saying penny wise pound foolish comes to mind.

 

[MaxBottomtime]

You sound very conservative. 700 psi is around 18 cu-ft (I think) in an 80 cu-ft tank. Obviously if 18 is too little,then a spare air would be out of the question for you. I'm curious, what is the minimum pressure you reach before starting an ascent from 100 feet?

It sounds like you are VERY cautious about the possibility of running too low on air. It would never want to criticize someone for using conservative safety protocols.

Do you exercise an equal degree of caution with respect to a response to a catastrophic failure of the regulator - like say a blown LP hose or something? What protocols are implemented for that unlikely occurrence?

I like spending the last portion of a dive in shallow water. If I'm diving from a boat, I will often go through my photos while making a long safety stop. If I'm diving at 100 feet, I typically leave the bottom around 1,000psi.

I've had two blown hoses in 2500 dives. One was at five feet so I just stood up. The other was at the surface. If I had a hose blow at depth I would likely have enough air to make an uneventful ascent. It would either be when I still had plenty of gas or when I had 1,000psi. Either way, I could ascend without a SpareAir or pony.

If I dive below 100 feet, I'm probably on doubles and deco bottles.

 

[AfterDark]

Maybe you are lucky. I can't count the number of times I have seen a plastic spg leak and allow water into the case. Most recent was a buddy around 5 months ago. It flooded on the first dive and he used it for the remainder of the day.

I (right now) have a aqualung plastic spg that has not leaked, but the needle goes no lower than 200 psi. I use it occasionally and would not loan it out, but it always seems to work over the normal pressure range.

Oh that explains it; luck has nothing to do with gear selection. All mine are brass chromed like my regulators; not to big on plastics for dive gear.

Try buying some good used SPGs on the vintage dive gear on Ebay that are metal, I think you'll have better luck, I know I do! My oldest SPG was between 30 40 years old when it finally started leaking and had to be replaced. I bought a newer but still used SPG about 10+ years ago on Ebay and haven't done anything but dive with it since.

 

[Bob DBF]

Spare air is nothing more than a false sense of security to the diver.

Only if the diver magically believes the Spare Air can deliver more air than it contains.

The problem with the Spare Air is that it is never the answer if you are properly planning and executing a dive

If you properly plan an execute a dive, there is no need for any redundant air.

Plastic SPG?! Do people actually use those things?

Manufacturers have been producing them from the '70's, there are probably more in use than the brass and glass. I've been using one I picked up in 1980 and it still works just fine. I've got others, some are brass and glass, just saying.


If one decides to carry redundant air, it is incumbent on one to properly determine what volume of air is proper to carry for their dive plan. 3 cuft may be too much and 40 cuft may be too little, depends.

 

[johndiver999]

I like spending the last portion of a dive in shallow water. If I'm diving from a boat, I will often go through my photos while making a long safety stop. If I'm diving at 100 feet, I typically leave the bottom around 1,000psi.

I've had two blown hoses in 2500 dives. One was at five feet so I just stood up. The other was at the surface. If I had a hose blow at depth I would likely have enough air to make an uneventful ascent. It would either be when I still had plenty of gas or when I had 1,000psi. Either way, I could ascend without a SpareAir or pony.

If I dive below 100 feet, I'm probably on doubles and deco bottles.

That sounds pretty reasonable to me, thanks.

 

[AfterDark]

Maybe you are lucky. I can't count the number of times I have seen a plastic spg leak and allow water into the case. Most recent was a buddy around 5 months ago. It flooded on the first dive and he used it for the remainder of the day.

I (right now) have a aqualung plastic spg that has not leaked, but the needle goes no lower than 200 psi. I use it occasionally and would not loan it out, but it always seems to work over the normal pressure range.

Most any mech gage is more accurate in the mid range of the gage. If a working 5000 psi gage reads 3000psi it's probably close. At either end of the scale accuracy drops off a bit.