SPG vs tank checker gauge

[AfterDark]

And that is the reason I trust my pressure transmitter over any analog gauges. The pressure transducers are much more reliable and accurate.

Ok sure, got proof of that statement? Try comparing it to another one of the same model on the same tank and get back to us. Unless gauges, any gauges are periodically calibrated deviation will occur over time.

 

[broncobowsher]

Reminds me of the saying that "A man with a watch always knows what time it is. A man with two watches is never sure."

Except the man with 1 watch is always 10 minutes late and can't figure out why he misses everything. meetings, planes, trains, etc. Also thinks all the clocks he passes alone the way are wrong as well.

 

[kelemvor]

Reminds me of the saying that "A man with a watch always knows what time it is. A man with two watches is never sure."

Probably why people rarely use watches for timekeeping these days. A cell phone that regularly gets it's time updated from a standard source is far better.

As for guages, you can calibrate pretty much any pressure guage. Do to it right, you need something like a fluke pressure calibrator. Pressure Calibrators | Fluke Pressure Calibration Tools A shop Might have the right tool but I think I'd just replace the gauge. So far, my digital gauges with transducers have remained accurate. At least, they still report the same pressure as my tank checker and the diveshop's tank checker.

 

[Sam Miller III]

From my files.......

Diving death - Catalina island dive park

Regulator ; SCUBA Pro Mark IV
1974 Catalog Page17
Last catalog which Mark IV appeared
( 46 years ago ! (Time flies )

SCUBA Pro Mk VI -- Automatic Self Locking Yoke
Life time one owner guarantee of all parts
$118.25
~~~~~~~~~~~~~~~~~~~~~~~~~~
Page 23
Pneumatic Pressure Gauge
Pt # 133 Tank Pressure gauge.....$20,00
Pt # 133-2 filler attachment …. ,,,.$18.00
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For many years I was a credentialed well known Professional Diving consultant expert diving witness
I was also on retainer to Impact General on all legal maters related to diving equipment and accidents and often testified in a court of law. as required.

One interesting Impact General case involved in was:

Fienberg vs SCUBA Pro, US Divers Aquatic Center etal (1982= 38 years ago}

All involved were personal friends
I called Dick Bonin, President of SCUBA Pro = He understood & had ample insurance coverage
I met with John Cronin GM of US Divers= Not happy but do what you are contracted to do
Met with my best friend at the Aquatic Center (AC) Ron Merker who was very up set as only Ron could be
(Ron was Dr. Bills basic instructor but " He didn't learn anything from Ron" )

The tragedy involved Dr, Fienberg a social friend of Cronin.
Cronin had sold Fienberg a PFV "out the back door" from US Divers
A Mark VI purchased used but "overhaled" from the AC

The victim went diving at the then new Catalina dive park with his daughter -- all was well until the end of the dive.

The scenario as I presented was was this:
He began his assent - became entangled in kelp-- struggled
He yanked on his PFV CO2 inflator -- didn't fire -didn't inflate
His Mark VI disengaged from the tank
He lost his life in a few feet of water entangled in kelp'

His body was recovered by life guards

The equipment was lab & field tested by the late Dr Glen Egstrom of UCLA--
(Also personal friends of mine and the defendants Bonin, Cronin & Merker)

Dr Egstrom testing disclosed
1) The CO2 had been factory installed with the mechanism in the fired position
2) The SCUBA PRO SPG reading was inaccurate by 200 + PSI
3) The Mark VI disengaged with excessive breathing demands and low pressure
3) The Mark VI had not been overhauled - and was in need of over haul

The court ruled in favor of the plaintiff in the amount of $250,000.00
Not what I and others expected with the loss of a Doctors life due to faulty equipment.
'
SDM 111 .

SPGs & Tank Checkers are mechanical devices and are subject to wear and tear and of course inaccurate readings
When introduced to the diving world in 1954 they were the were the state of the art and were often used in conjunction with a J (reserve) valve.

Some will possibly read high others will read low. Divers should have PRIDE aka Personal Responsibility In Diving Efforts -- but most don't !

Sam Miller, III

 

[Nathan Doty]

I used to fly small planes. We dipped the tanks as part of preflight. They had a fuel gauge in the dash. The FAA requires, again REQUIRES, a fuel gauge be accurate at exactly 1 point, and that is when it reads empty. So we dip the tanks... Anything with a needle is a ballpark estimate.

 

[Lostdiver71]

Ok sure, got proof of that statement? Try comparing it to another one of the same model on the same tank and get back to us. Unless gauges, any gauges are periodically calibrated deviation will occur over time.

I have multiple transmitters and have checked them against each other! All 3 were within 50 psi of each other an a full 3500 psi tank, I need to do the same thing on a tank that only has about 600 psi and let you know what I get.

 

[NAM001]

And that is the reason I trust my pressure transmitter over any analog gauges. The pressure transducers are much more reliable and accurate.

WE HAVE OPPOSING OPINIONS I have had 4 AI usnits and they all are shot by tghe end of the first or second year. all off by about teh same 300 psi on either teh high or low end. I have thrown 2 away and just found 2 more in a drawer. I have never ever had a faulty reading SPGYes there is some error between then both they alway read with in a few pounds of each other and agree with the fill stations gages on both the 500 range and 3000 range. At this point I will never use one as a primary source sensor. I would throw them in the trash before letting any one use them. I would give them away but I would not condemn any one to using one of them. I assume they are being built better than in the distant past 2000-2010. I have had one read 400 psi when the tank was empty and the rest were off in the high end or both high and low ends.

 

[Lostdiver71]

WE HAVE OPPOSING OPINIONS I have had 4 AI usnits and they all are shot by tghe end of the first or second year. all off by about teh same 300 psi on either teh high or low end. I have thrown 2 away and just found 2 more in a drawer. I have never ever had a faulty reading SPGYes there is some error between then both they alway read with in a few pounds of each other and agree with the fill stations gages on both the 500 range and 3000 range. At this point I will never use one as a primary source sensor. I would throw them in the trash before letting any one use them. I would give them away but I would not condemn any one to using one of them. I assume they are being built better than in the distant past 2000-2010. I have had one read 400 psi when the tank was empty and the rest were off in the high end or both high and low ends.

We are allowed to have opposing opinions! I have seen many pressure gauges that were accurate and many that were not over the years. My transmitters are a few years old and I have had no problems with them, only had to change batteries.

 

[ATJ]

I have been planning to test my transmitters and SPGs for some time. This thread prompted me to finally do it.

I have three sets of regs: main, pony and backup. Each has a transmitter and an SPG. Note that the pony set is a yoke so I can't test on the 300bar tank.

The transmitters give far more precision and I could only estimate where the needle was on the SPGs. This is particularly true for the near empty tank.

Note that the only accurate way to compare is with both on the same regs at the same time. Checking one, purging, putting the next reg set on will result in a slight loss of air.

I first compared the transmitters to the SPGs on three different tanks.

Full 300bar 12L
Main TMT: 301
Main SPG: 300

Backup TMT: 299
Backup SPG: 305

Full 232bar 15L
Main TNT: 232
Main SPG: 232

Backup TMT: 231
Backup SPG: 235

Pony TMT: 232
Pony SPG: 237

Near empty 232 15L
Main TMT: 16
Main SPG: 15

Backup TMT: 16
Backup SPG: 15

Pony TMT: 16
Pony SPG: 15

Next I moved the Pony TMT and then the Backup TMT to my main regs to compare the transmitters side by side.

Full 300bar 12L
Main TMT: 300
Pony TMT: 301

Main TMT: 299
Backup TMT: 300

Full 232bar 15L
Main TMT: 231
Pony TMT: 232

Main TMT: 229
Backup TMT: 230

Near empty 232 15L
Main TMT: 16
Pony TMT: 16

Main TMT: 16
Backup TMT: 16

 

[2airishuman]

As pointed out upthread, SPGs that read incorrectly can be part of an accident chain.

It is common for them to off by 100 PSI even when new. Any more than that, or any sticking however minor, and I discard them.