carbon monoxide in tanks - cozumel

[MMM]

I'm afraid that would be the vast majority of them!

Badly worded question and supposition. The vast majority do or do not test?

 

[DandyDon]

Badly worded question and supposition. The vast majority do or do not test?

Most don't. When I used to try asking about quarterly tests as required by Padi, I usually got excuses. Padi no longer requires, but then I learned that those were not a dependable source anyway.

When Dive Palanacar had the recent incident, they could not find a CO tester to check their tanks.

I doubt that any compressor on the island there and few in the Caribbean have an inline monitor with auto cut-off.

It's test your own or just hope.

 

[jfcl01]

Suprane

thanks for all the work, educating us on your CO monitor...I am considering the toxi-rae...
my question-do you know of any other options for calibrating? I am wondering if I could take it somewhere, or send it in...rather than the big outlay for the gas and reg. I wonder this because my diving is limited to 2-4 dive trips per year (and it's usually 2 trips of about 12 days each)

 

[DandyDon]

Suprane

thanks for all the work, educating us on your CO monitor...I am considering the toxi-rae...
my question-do you know of any other options for calibrating? I am wondering if I could take it somewhere, or send it in...rather than the big outlay for the gas and reg. I wonder this because my diving is limited to 2-4 dive trips per year (and it's usually 2 trips of about 12 days each)

It'd be nice if your dive club or LDS would get involved, huh - at least with calibrating? I don't know that the detector is something one would want to loan out.

It's hopped that the LDSs with Analox inline monitors will calibrate their new personal tester, but - it may not be any cheaper.

 

[Ayisha]

Oh really now?! There shouldn't be any. 10-15% is legal in most of the few countries that regulate, UK is 3%, Mexico doesn't regulate - but that sucks. If it could be 5-6 ppm, on a bad day what's to stop it from being 15-20? Damn! :shocked2:

Please be careful about expressing the allowable amount of CO as a percentage. 10% translates to 100 000 ppm while even 3% translates to 30 000 ppm - waaaay off the chart! The regulations are between 3 and 15 Parts Per Million, as you stated later in your post. That is a maximum of 0.0015%. It is an extremely small amount and that is why it is expressed in PPM. I am quite sure that you know that and just slipped in the post, but I just wanted to make sure that other people that may not know don't get confused.

 

[DandyDon]

Thanks Ayisha - my bad. Changed

 

[IyaDiver]

Gentlemen,

Fisrt of all I ( we ) must thanks SwampDiver and the rest of the guys here who has been pushing hard telling us how important CO monitoring is. Last year I been researching on suitable CO meter and if it weren't for SwampDiver who has wrote about it in great details going back years ago, i would not have known fine details about CO meter until I buy them.

So now I got Toxi RAE 3. CO , type is 0-500PPM. Model is PGM-1700 , firmware 1.7 and this is not a disposable unit.
Second unit is a QRAE 2 Diffusion model ( C0 + oxygen )

Here is the sample of both units response to CO from my cigarette smoke, if this can help anyone to have a better picture.

Photo 1
I started the stopwatch on the blackberry. I blew cigarette smoke on the units twice.
NOTE : The smoke spread is not probably equal to both units.
QRAE 2 reads 13 ppm, Toxi RAE3 reads 4ppm. Time passed 8.67 seconds
Sensor placement is lower in QRAE 2 and higher in ToxiRAE 3. Sensor size is bigger ( area ) in QRAE2 than in ToxiRAE 3, this may result in QRAE 2 reading higher and faster.

Photo 2
I placed a lighted cigarette close to the units, in fact the wind direction was to the units. QRAE 2 reads 23PPM and ToxiRAE 3 reads 30ppm. Time passed 1:33.87


Photo 3
Stop cigarette smoke but living room still has the trace of cigarette smoke.
QRAE 2 reads 14PPM and ToxiRAE 3 reads 4PPM. Time passed 1:45.43


Photo 4
Stop cigarette smoke but living room still has the trace of cigarette smoke.
QRAE 2 reads 5PPM and ToxiRAE 3 reads 0 PPM. Time passed 2:08.15


Photo 5
I went to my bedroom to get CO free air.
QRAE 2 still reads 2 ppm and Toxi Rae reads 0 PPM. Time passed 4:36.98


Photo 6
I blow emergency breathing oxygen ( must be 100% 02 but never test ) to units, QRAE2 reads 0 PPM and ToxiRAE 3 reads 0 PPM. Time passed 6:18.49

This is not a very scientific test but its shows that the QRAE2 when used in open air, is more sensitive and reads faster than ToxiRAE 3. Looking at the sensor port size, it makes sense.

ToxiRAE 3 reading within 12 seconds ( as stated in manual ) seems true for now. Until I get my 10 PPM CO calibration gas, I do not know if 12 seconds or perhaps faster is the time required to get maximum reading and a stable one. One thing for sure, it respond fast when CO is aimed at it. I did blow cigarette smoke directly into it with the supplied small hose that has an adaptor that will click on the sensor, it went like 40something PPM...

ToxiRAE 3 reads back to zero PPM fast is also probably because manufacturer blanks out 0-3PPM reading on some models ( SwampDiver told me and I checked with manufacturer , its true). This is to prevent nuisance readings.

Here is what I was told by the dealer :

I have gotten a lot of information back from our internal guys on this topic and your source is correct in saying that all mfg will have what is called a ‘dead band’ in their units for certain sensors.

For RAE the deadband is confirmed to be 0-3 ppm. You will not get any reading in this range for all RAE units with CO sensors.

So my understanding on the dead band is, you will read a decreasing reading even at 3,2 and 1 PPM but most likely can't read increasing reading 1,2 and 3PPM , perhaps an immediate jump to 4 PPM.

Hope this is useful.

Cheers,
IYA

 

[swamp diver]

I have gotten a lot of information back from our internal guys on this topic and your source is correct in saying that all mfg will have what is called a ‘dead band’ in their units for certain sensors.

For RAE the deadband is confirmed to be 0-3 ppm. You will not get any reading in this range for all RAE units with CO sensors.

So my understanding on the dead band is, you will read a decreasing reading even at 3,2 and 1 PPM but most likely can't read increasing reading 1,2 and 3PPM , perhaps an immediate jump to 4 PPM.

Hope this is useful.

Cheers,
IYA

The 'dead band' or 'blanked out' region in a sensor is essentially to reduce nuisance calls in an occupational setting from sensor drift due to high ambient heat or low background but safe levels of the contaminant in question.

It is much simpler than you allude to in that the blanked out band is the same whether the reading is increasing or decreasing.

For diving applications where some national standards now only allow a maximum CO concentration of 3 ppm in compressed air (Britain) one does not want a display blanked out from 0 to 3 ppm.

Here are the blanked out bands for various models of CO monitors:

Rae Systems ToxiRae 3: NONE. This unit reads 0, 1, 2 ppm, etc.
Rae Systems ToxiRae 2: 0 to 3 ppm
Rae Systems QRAE 2: ?0 to 1 ppm (if you can see 2 ppm in the photo above it is not blanked out)

BW Technologies Gas Alert Extreme: 0 to 2 ppm

Pocket CO Non-diving model: 0 to 4 ppm


Unless living in a jurisdiction where the maximum CO specification is 3 ppm all of these units except the ToxiRae 2 will suffice for our purposes although it is better to know if there is 2 ppm CO in one's breathing air than not.

Stick with the ToxiRae 3 as there is no blanked out band, at least with those units sold in Canada and the USA.

 

[jfcl01]

Swamp Diver rocks.

 

[IyaDiver]

Peter,

I willl play more with my RAE and report back.

Thanks
IYA