Sensorcon 20% discounts thru April 25

[divinh]

Dandydon answered you with the best answer. It shouldn't have to fall on the diver. It should become an industry standard. There's a well known fill station in cave country that pumped a bunch of co unknowingly and didn't have inline sensors. The divers caught it and all was well. That story has circulated cave country so you would think all of the shops would have added inline monitors. Nope. So when I need fills there I go to the fill station(s) that have inline monitors.

If you don't want to pay for a monitor then you need to be willing to ask whoever provides the tanks to also provide a co reader to you. Them having inline isn't good enough necessarily. Not all inline (like mine) shut off the compressor. Some just scream a high pitch. That's ok for me filling in my garage, but many shops' tank monkey is so far from the compressor they may not hear the scream. The owner of the fill station I mentioned above will start his compressor and then drive away for an hour or so to do errands with nobody around to monitor. His compressor shuts down at a certain psi or if the oxygen gets too high, but I'm 95% sure his inline co monitors that are supposed to be in place don't have the ability to shut off his compressor(don't quote me but I'm pretty positive as I was just there the other day). So do your diligence and only accept tanks from a source that provides monitors or have your own.

It seems like, with awareness of CO, divers would speak with their wallets and avoid filling stations that don't have CO monitors. The filling stations that don't use monitors will eventually lose business and either adopt or go out of business. Diver awareness seems key to getting filling stations to adopt.

The reason I'm on this thread in the first place is because I wanted to pay for a tester and I bought one, the Sensorcon. Now, there's uncertainty with its effectiveness as a tool for divers. It's why I sought for clarity on testing methodology. If the Sensorcon can't test directly within a pressurized air stream, can it test with a pocket of captured air? Or will only top-of-the-line suffice, in which case, why not only buy inline monitors with auto shutoffs, as in your case? Was cost an issue? If cost is an issue for divers, then will a Sensorcon suffice? Are there regulatory standards for CO testers that all testers must meet? And regarding the price difference between a low-end vs a high-end, the more expensive cost means more features, but not necessarily less safety? (For example, regulators have a large range in pricing, but the most cheap ones will serve a diver, provided it has passed industry standards.)

Given that not all dive ops have monitors yet, what can a diver do if he/she is going on a liveaboard where air is provided by only one filling station? Bring his/her own tester? Fine. Now, what's a safe tester to use without breaking the bank?

 

[DandyDon]

Now, what's a safe monitor to use without breaking the bank?

Well, a monitor is something on all the time, like an inline monitor for a compressor.

For a tank tester, there are several choices now - some better and more expensive than others. The Sensorcon in a ziplock may not be as accurate as the pricier models, but I think it'll be close enough to alert you to possible dangers. Just make sure it reads zero in clean air and a few digits when you blow on it. If tank test show a 3, consider complaining and maybe canceling, but after all it took to get you onto the liveaboard - it'd probably take more to get you to cancel. If a tank test reads a 30, bail.

I started with the Pocket CO, but wouldn't suggest it to anyone - too many problems. Color changing stickers are okay for a vehicle, but not enough for tank tests.

 

[divinh]

Well, a monitor is something on all the time, like an inline monitor for a compressor.

For a tank tester, there are several choices now - some better and more expensive than others. The Sensorcon in a ziplock may not be as accurate as the pricier models, but I think it'll be close enough to alert you to possible dangers. Just make sure it reads zero in clean air and a few digits when you blow on it. If tank test show a 3, consider complaining and maybe canceling, but after all it took to get you onto the liveaboard - it'd probably take more to get you to cancel. If a tank test reads a 30, bail.

I started with the Pocket CO, but wouldn't suggest it to anyone - too many problems. Color changing stickers are okay for a vehicle, but not enough for tank tests.

Thanks for the correction in the distinction between monitor and tester and providing a sensible methodology. Previous post edited for correct terminology.

 

[Jay]

A question about in-line monitors (with auto-shut offs). DAN AP last week emailed about their campaign re CO - link: DAN Divers Alert Network Asia-Pacific : Membership and Insurance for Scuba Divers (Yes, @DandyDon they heard you before you wrote your post!!). In their text they say "CO contamination usually arises from impurities in the air taken into the compressor or from contaminants generated by the compressor itself." The quote seems to imply the compressor might introduce CO directly into its tank aside from the air intake. This seems wrong to me, and is possibly just a sloppy sentence.

They also fail to specifically mention in-line monitors, although they do say "Regularly check the quality of the air: this can be done by using detector tubes and other non-reusable devices, or with electronic analysers. Alternatively, and required in some regions, air testing by accredited laboratories can be done."

As per DandyDon below, wouldn't the smartest campaign simply be for us divers to insist / only get fills from places with in-line monitors (with auto-shut offs) and where all Operators need to maintain and furnish tank testers??

Yep, yep, yep...!

His suggestion was better: "I'm not saying every diver has to own their own, but at a minimum every dive shop and every dive boat should have one for their customers to use, and should advertise/recommend it's use."

And this is why DAN, the agencies, and the operators in general are not supporting this very important need. Even with all the good by DAN, they all depend on freely flowing money driving the business & sport. The solution is not that bad tho. All they have to do is agree that Compressors need to have inline CO monitors with auto cutoffs and all Operators need to maintain and furnish tank testers. They did it with Nitrox because that supported additional classes, cards, and compressor fees, but there is no profit in uncovering CO risks. Their general goal is to keep injuries down enough to be blamed on Travelers Flu.

How much would the solution cost? Pennies per tank.

From DAN AP's email - link is in first sentence above.

 

[DandyDon]

yes, @DandyDon they heard you before you wrote your post!!

Oh, I have mentioned DAN before. Once years ago I even called to ask what they could do about the CO risk, tried asking for the Chairman, and was amazed that he took my call - and agreed with my remarks, verbally at least. That one has long since retired, I think.

or from contaminants generated by the compressor itself." The quote seems to imply the compressor might introduce CO directly into its tank aside from the air intake. This seems wrong to me, and is possibly just a sloppy sentence.

Nope, not a mistake. Overheated compressors can partially burn their own lubricating oil adding CO.

As per DandyDon below, wouldn't the smartest campaign simply be for us divers to insist / only get fills from places with in-line monitors (with auto-shut offs) and where all Operators need to maintain and furnish tank testers??

Nice idea but not likely. Test your tanks, let them know you're testing, complain if you even find a small amount, whine & gripe because they don't do more.

 

[Dan]

I think this sersorcon is good enough for testing / monitoring CO level to be below OSHA PEL of 50 ppm, the limit of CO concentration in the breathing air for human to breathe for 8 hours, Chemical Sampling Information | Carbon Monoxide | Occupational Safety and Health Administration

I carry the setup below after reading @DandyDon post on CO long time ago.

Just checked the hotel room CO level by pumping the rubber bulb several time. CO level went up from 1 to 5 ppm and level off there (an order of magnitude lower than the OSHA PEL). I’ll check my tanks tomorrow.

As you can see in the setup (above), down stream of the rubber bulb has a T fitting to vent off the over pressure (as your hand squeezing the bulb) and there is a one-way check valve to insure the air going from the tube onto the sensor, not the other way around (sucking outside air near the sensor and tube fitting, which would be diluting the air flowing onto the sensor). The pumping frequency is 1-2 seconds over a 15-20 second period to provide a sufficient sample for the Inspector’s sensor.

 

[Jay]

In their text they say "CO contamination usually arises from impurities in the air taken into the compressor or from contaminants generated by the compressor itself." The quote seems to imply the compressor might introduce CO directly into its tank aside from the air intake.View attachment 458275

Nope, not a mistake. Overheated compressors can partially burn their own lubricating oil adding CO.

(But) Wouldn't that burnt lubricating oil be adding the contaminant CO via the air-intake? (or am I miss-understanding the mechanics of a typical compressor - in which case an in-line monitor would not be picking up CO via this source).

I think this sersorcon is good enough for testing / monitoring CO level to be below OSHA PEL of 50 ppm, the limit of CO concentration in the breathing air for human to breathe for 8 hours, Chemical Sampling Information | Carbon Monoxide | Occupational Safety and Health Administration.

Don't forget those are 1ATM

 

[Dan]

(But) Wouldn't that burnt lubricating oil be adding the contaminant CO via the air-intake? (or am I miss-understanding the mechanics of a typical compressor - in which case an in-line monitor would not be picking up CO via this source).

Don't forget those are 1ATM

If compressor is like piston engine, using several oil-lubricated metal-ring seals that form thin film on the cylinder cavity and the air in the compressed cylinder gets too hot, as the piston sliding up & down the cylinder, compressing the air, to the point of incomplete combustion of the oil, the product of the incomplete combustion is CO.

The Sensorcon CO sensor reads accurately at / very near 1ATM. That’s why the kit comes with a T fitting (circled in red in the close up picture, below), where most of the sample gas from the rubber bulb is mostly vent out as you squeeze the bulb.

 

[DandyDon]

First about the advice to use the Analox dome. Has anyone really tried this? I took a locally filled air tank, tested it with my Analox CO meter and it read 0 ppm. Then I put the dome on the Sensorcon and again tested the same tank and the readings went up to 30 ppm. Then I used the Ziploc plastic bag method and the Sensorcon read 2 ppm. I suspect the air pressure is affecting the sensor somehow. After all it's not designed to test pressurized tanks. In any case the readings that I found are all over the place and unreliable so I plan to return it and swallow the restock and shipping fee.

Yes, I think we overlooked flow rate pressure affecting the Sensorcon readings. If you drop the unit into a gallon ziplock, then fill the bag from the tank, you should get a good reading. However directing tank gas into the unit seems to give false positive readings. Still a good, economical choice, but not under any pressure.

 

[DavidFL]

I bought a Sensorcon during the earlier part of this thread using the discount. Followed the other conversation in the thread about testing under a flow from a tank and experienced similar results using the dome from my DIY El-Cheapo O2 analyzer. I subsequently bought a Cootwo, but i'm keeping the Sensorcon. Have learned a lot about the CO I'm exposing myself to on my bike rides on the highway shoulder, and plan to keep the Sensorcon on all the time in live-aboard staterooms and some hotel rooms. I will use the Cootwo for tanks, but the Sensorcon and plastic bag method as a backup.