Continued Carbon Monoxide - Cozumel

[RubberDucky]

I had two different Coz Ops send me test results from the main fill station after this thread started, in two different formats. I'll attach both, but I have come to think that they are worthless as the samples are possibly taken right after the filters are changed and when the compressors are first started, which is how I would do samples for public disclosure. Only an inline monitor really gives good info, and - I'm still going to check my tanks even if I see them filled then & there. The more I learn, the more I fear.

You'll notice that there were only 4 tests over 2 years at that...! :shocked2:

Agree - those samples are completely worthless in regards to CO (and maybe everything else on the list). Do those samples reflect the blatantly oily air in the tank that our DM Carlos let me smell (distinct smell), taste (distinct taste), and test for CO (ok)? No, they do not. Do those samples reflect the 30ppm avg of carbon monoxide I repeatedly found in a tank filled by Meridiano 87 earlier this year? No, they do not. That was my first trip with a CO detector, and that was maybe the 10th - 15th tank I'd ever tested.

I wonder how many people here than run dive ops would knowingly dive a tank with 30ppm of CO? Apparently all of them, because if you're not testing your air, you simply would not and could not know otherwise. You know bad air can happen, yet you're willing to risk it for yourselves and your own loyal customers, most of whom are unaware of the potential danger.

Perhaps if I too had sucked down countless tanks of air over the years without issue then I would not see the need for improving on things that appear to be working just fine. It goes back to the adage "if it ain't broke, don't fix it". Past experience, however, cannot predict the future. I cannot prove based on experience alone that I will find another bad tank in the next 10 - 15 tanks I test any more than you can prove that you will not. Dive ops: please, stop living in Candyland and get off the Internet for 10 minutes and learn how to use a hand held CO detection device.

 

[John Doc]

Dan--

It may seem like few people care about testing CO in tanks, but lurkers read this thread and their awareness is being raised (I know this for a fact). Some may even get a CO tester without posting about it. You're making progress that may not be readily apparent, but it's progress nonetheless.

I am one of those lurkers. After reading about the divers that had bad tanks in Cozumel. I went out and bought a tester before we went down there last month. It's a small investment and sure gives you piece of mind. Thanks Don keep up the good work.

John

 

[cruiser]

Picked up 2 tanks from the LDS. 0 ppm CO in each

 

[DandyDon]

Agree - those samples are completely worthless in regards to CO (and maybe everything else on the list). Do those samples reflect the blatantly oily air in the tank that our DM Carlos let me smell (distinct smell), taste (distinct taste), and test for CO (ok)? No, they do not. Do those samples reflect the 30ppm avg of carbon monoxide I repeatedly found in a tank filled by Meridiano 87 earlier this year? No, they do not. That was my first trip with a CO detector, and that was maybe the 10th - 15th tank I'd ever tested.

I am one of those lurkers. After reading about the divers that had bad tanks in Cozumel. I went out and bought a tester before we went down there last month. It's a small investment and sure gives you piece of mind. Thanks Don keep up the good work.

John

Which testers are y'all using...?

Picked up 2 tanks from the LDS. 0 ppm CO in each

Always reassuring. Don't get bored with all of the -0- readings in a row. It's just a good practice, and when you do get a significant reading, shoot a video clip like RB did. I just did not think to do so. :blush:

 

[John Doc]

We were using the portable Analox unit.

 

[RubberDucky]

Which testers are y'all using...?

The ToxiRAE 3. I used the instructions posted by forum member suprane here. It did its job wonderfully and I'd recommend it to anyone.

This is the setup:

1. ToxiRAE 3 CO detection device (0ppm - 500pm - very important!)
2. calibration gas (bottle of CO, 10ppm, good for 3 years)
3. regulator for the gas (screws into the top of the CO tank, goes up to 600 PSI. I think the bottle of calibration gas I bought was 250 - 300 PSI brand new. I left this attached to the calibration gas cylinder for a few days and it leaked a little bit as a result. So, don't leave this connected when not in use)
4. BC connector (this hooks into the LP hose on your BCD when you are testing your air)
5. plastic tubing (you can get this at a hardware store such as Home Depot. Take the BC connector and black plastic connector piece (with its 1 inch plastic tubing that comes with it) from the ToxiRAE 3 with you so that you know which size of plastic tubing will fit very snugly over both)

The BC(D) connector and plastic tubing are not mandatory. They are only for the convenience of quickly testing gas, as opposed to placing the device inside a bag, filling the bag with air from the tank, and waiting a few minutes (or however long it takes, I'm not really sure).

Before using the device, it must be calibrated, which means that you are configuring it to detect CO at very low levels. This is why the calibration gas is a very low 10ppm of CO, and why this model of ToxiRAE 3 will test as low as 0ppm. Instructions come with the ToxiRAE 3 that detail how to do this. What I forgot to include in the picture is a black rubber hose that ships with the regulator. One end attaches to the top of the regulator, and the other can be attached to the black plastic piece shown connected to the top right of the ToxiRAE 3. That little black plastic piece with about an inch of plastic tubing comes with the device.

After it's been calibrated, it's really simple to test the air in your tank. Just clip the black plastic piece onto the front of the device as shown, and hook the BC connector into the low pressure (LP) hose on the BCD (you must disconnect it from the inflator first of course). Then, after you've turned the device on, if my memory serves me correctly you just need to push a button or 2 to set it to "bump gas testing" mode, then turn the air on in your scuba tank. It seems to me it generally only took a few seconds before I started getting readings.

I've probably made the whole process sound more difficult than it is, but if I wrote detailed instructions on how to drive a car (open door, sit down, close door, put foot on brake, insert key, turn key, let go of key, take off e-brake, etc etc), that would also sound complicated despite the fact that it's second nature to most of us and didn't take long to learn at all. Honestly it's not difficult, and the instructions that come with the ToxiRAE 3 are very straightforward and easy to follow.

Happy testing!

 

[swamp diver]

and waiting a few minutes (or however long it takes, I'm not really sure).

Happy testing!

Thanks for the nice review.

What you are asking above is the response time for the sensor which is usually listed in the monitor's specifications under the T90 which is the time to reach 90 percent of the reading.

The T90 listed for the ToxiRae 3 is < 12 seconds, the Analox unit < 15 seconds, and the BW Tech Gas Alert Extreme somewhere about 30 seconds. I'm not sure about the Pocket CO although the scuba instructions do say to leave it in the bag for 3 minutes.

The advantage of a fast sensor or low T90 is one can check multiple tanks very quickly on a dive boat.


One other small point is to purchase a 0.5 lpm rather than 1.0 lpm calibration gas regulator which will half the volume of gas used during calibration and bump checks.

 

[DandyDon]

TOne other small point is to purchase a 0.5 lpm rather than 1.0 lpm calibration gas regulator which will half the volume of gas used during calibration and bump checks.

I think that this is the site you suggested for ordering calgas BuyCalGas.com - GASCO Precision NIST Traceable Calibration Gas Carbon Monoxide, Need Help? Call: (866) 905-9795 and I recall you said to phone to request 10 ppm since it is not listed on the menu but is available at the same price. Too bad LDSs and other local suppliers are not carrying it as shipping is $32 for 1 or $36 for 12 on the 10 Liter tanks, not much more on the 17 Liter tanks that cost the same before shipping.

I notice that the Regulator for the 10 Liter is Shaving Cream or Trigger Aerosol; would that work? Spend more on calgas, but not need the $100 reg.

The 17 Liter requires a 71-Series, 72-MFV/17, CV-2 Regulator, of course.

 

[swamp diver]

I think that this is the site you suggested for ordering calgas BuyCalGas.com - GASCO Precision NIST Traceable Calibration Gas Carbon Monoxide, Need Help? Call: (866) 905-9795 and I recall you said to phone to request 10 ppm since it is not listed on the menu but is available at the same price. Too bad LDSs and other local suppliers are not carrying it as shipping is $32 for 1 or $36 for 12 on the 10 Liter tanks, not much more on the 17 Liter tanks that cost the same before shipping.

I notice that the Regulator for the 10 Liter is Shaving Cream or Trigger Aerosol; would that work? Spend more on calgas, but not need the $100 reg.

The 17 Liter requires a 71-Series, 72-MFV/17, CV-2 Regulator, of course.

The best thing to do is find a calibration gas supplier in your neighborhood as the shipping will be incorporated into the price. I pay about $US65 for 34 litres all in and that is with shipping and customs brokerage from Florida where Gasco is located. You can call Gasco in Florida and ask who their distributor is nearest you.
http://www.gascogas.com/gas.htm

Here is another supplier from the west coast.
Carbon Monoxide Calibration Gas, CO Calibration Gas, Industrial Gas Supplier

The shipping of the cylinders is considered hazmat due both to the pressure and contents which is why the cost is increased.

The 10 litre bottles with aerosol are meant for a quick check on the calibration but not for calibration itself. One inflates a small balloon with the amount of gas needed for the bump check and then releases it into the monitor to check on its current accuracy. If within spec one can continue to use the monitor but if out of spec a full formal calibration is needed. These small aerosol containers are what we use in the field for daily checks on the instrument accuracy rather than carrying around a big bulky calibration bottle with regulator. Only thing though is you cannot take them on a passenger aircraft.
Squirt® Gas Bump Tester

Again the faster the sensor the less gas one uses to bump check or calibrate these monitors. The ToxiRae3 takes a minute to complete its calibration cycle while the BWT Gas Alert Extreme takes 2 minutes to calibrate which is double the gas volume. Faster sensor and low-flow regulator conserves calibration gas.

 

[swamp diver]

Don you mentioned your LDS has an Analox CO Clear installed on the shop compressor which means they have a bottle of calibration gas and regulator. If they have one of the older Analox CO Clear fixed monitors they were calibrated using 20 ppm CO but the newer ones use 10 ppm CO calibration gas. While the 10 ppm gas is ideal for calibration purposes the 20 ppm will suffice.

You can adjust the calibration gas concentration accepted by the ToxiRae 3 and the BWT Gas Alert Extreme units from 5 to 50 ppm.

You could buy one of these portable units and then pay your LDS for a calibration every 3 to 6 months rather than purchasing your own calgas and regulator. Ten to fifteen dollars for a calibration would be a fair price.