Spg backup to transmitter

[Nemrod]

I might not feel comfortable using some cheap off-brand tiny knockoff button gague. But if you wanted to use something like that and wanted a more reliable solution, just use a regular SPG on a 6" hose. Yeah, it's a bit more money, but much more reliable and more flexible in terms of mounting for optimal visualization.

What is good for the goose is good for the gander, if you have other than anecdotal data that can provide proof that the mini (one inch face) gages are any less reliable than a standard spg I would be interested. I did drop one with the full weight of the bottle behind the impact and it cracked the glass. Then the glass popped out at 100 feet, this being on my solo pony, but the gage continued to work, just another anecdotal story.

Regarding TXs and SPGs in general, I doubt there is any "study" that would prove or disprove one being more or less reliable than the other. An SPG has a spool with two O rings, the TX has batteries and electronics and can be subject to interference. Seems like an even trade and if anything weighted to the advantage of the SPG. That being an opinion based on anecdotal observation.

 

[doctormike]

What is good for the goose is good for the gander, if you have other than anecdotal data that can provide proof that the mini (one inch face) gages are any less reliable than a standard spg I would be interested. I did drop one with the full weight of the bottle behind the impact and it cracked the glass. Then the glass popped out at 100 feet, this being on my solo pony, but the gage continued to work.

I have no evidence of that at all. Indeed, I'm pretty sure that no one in this thread has anything other than anecdotal evidence for any of these presumptions, but that doesn't mean that it's not worth discussing.

I guess I was just saying that if you (1) wanted to backup your TX with an SPG, and (2) you were concerned about the reliability of button SPGs in particular, it's pretty easy to just use a regular SPG on a short hose instead of a button SPG, right?

Regarding TXs and SPGs in general, I doubt there is any "study" that would prove or disprove one being more or less reliable than the other. An SPG has a spool with two O rings, the TX has batteries and electronics and can be subject to interference. Seems like an even trade and if anything weighted to the advantage of the SPG. That being an opinion based on anecdotal observation.

Maybe I lost the original point of this thread, but I thought we were discussing the advisability of a SPG backup to a TX. Not the choice BETWEEN an SPG and a TX.

 

[Nemrod]

I have no evidence of that at all. Indeed, I'm pretty sure that no one in this thread has anything other than anecdotal evidence for any of these presumptions, but that doesn't mean that it's not worth discussing.

I guess I was just saying that if you (1) wanted to backup your TX with an SPG, and (2) you were concerned about the reliability of button SPGs in particular, it's pretty easy to just use a regular SPG on a short hose instead of a button SPG, right?



Maybe I lost the original point of this thread, but I thought we were discussing the advisability of a SPG backup to a TX. Not the choice BETWEEN an SPG and a TX.

@doctormike, I was just really messing with you. I know, I know and I have no argument against you, you are as usual, most logical sir.

James

 

[doctormike]

@doctormike, I was just really messing with you. I know, I know and I have no argument against you, you are as usual, most logical sir.

James

Of course! And I love these discussions... I'm not here to win, I'm here to learn. Thanks so much for indulging me...

 

[lostsheep]

What is good for the goose is good for the gander, if you have other than anecdotal data that can provide proof that the mini (one inch face) gages are any less reliable than a standard spg I would be interested. I did drop one with the full weight of the bottle behind the impact and it cracked the glass. Then the glass popped out at 100 feet, this being on my solo pony, but the gage continued to work, just another anecdotal story.

Regarding TXs and SPGs in general, I doubt there is any "study" that would prove or disprove one being more or less reliable than the other. An SPG has a spool with two O rings, the TX has batteries and electronics and can be subject to interference. Seems like an even trade and if anything weighted to the advantage of the SPG. That being an opinion based on anecdotal observation.

I sure hope the design engineers did some kind of “study” to validate their product ; someone knows the MTBF for each.

 

[Nemrod]

I sure hope the design engineers did some kind of “study” to validate their product ; someone knows the MTBF for each.

Maybe they did. Most all SPGs come from the same place in Italy. They have been making the same basic produts forever for everybody. Who knows where all of the bits and pieces that go into a TX come from or if they always are sourced via the same pipeline. A chip from here, a transistor from there, next month just the opposite, and then the receiver in the computer, how reliable is that, it is a two part system? You are right, you might think there would be such data. Are TXs CE? If so that may be a way to get to the data? I do not know however, SCUBA manufacturing companies seem especially adept at hiding anything like actual data or useful information about anything from the consumer. After all, we are too stupid to install a new exhaust valve in a second stage body in their opinions ---- . Like whatever would we cattle do with such complicated and highly technical information?

When an spg fails it usually does not stop reading the pressure. It may fill with water, it may have a leak in the spool or even the hose might start to sweat. Rarely a hose actually blows, in which case I guess we are SOL. Because then it will stop reading .

 

[Scuba fryd]

I use two PPS on my SM regs and no analog gauges at all. Works very well and no issues at all.

You can add button spg directly to first stages for redundancy.

What's a pps

 

[Rayk]

What's a pps

Pelagic Pressure Systems. Manufacturer of widely used transmitter.

 

[SlugLife]

For context, I do "recreational" SideMount. I subjectively like having a normal SPG on a short-hose, because it lets me check tank-pressure somewhat accurately during equipment setup without using my dive-computer.

The redundancy is nice I suppose, but not necessary for my diving. However, if my AI failed and I had a button gauge, I'd continue the dive mostly normal, but turn just a little early, because it can be hard to tell the difference between a few hundred PSI. The fact that a button gauge is a pain to read is mostly irrelevant, because we're talking something that's likely to affect much less than 1% of your dives.

And if I'm just doing normal open-water recreational diving, there's still the fact that I have two tanks to work with, so even if I'm not really getting an accurate read on one tank, I still have the other tank as a backup.

 

[DirtFish]

Sidemount, AI Shearwater Swift for the win. I do use 2 Shearwater computers though.