CO and Nitrox Testing Hardware Simplified

[TomZ]

Please, this thread isn't to debate the merits of Gas analyzing, Nitrox or Carbon Monoxide. It's just a how-to of my latest process. There are other threads for debating the merits of testing.


My current hardware:

The El Cheapo II from Qxycheq is a DIY kit. If you have soldering skills, you can save some money. The boxes are cheap ones from Piranha Dive Mfg. The CO analyzer is the Analox unit. The BC hose adapter is from Oxycheq also. I've been using the Nitrox analyzer first, then unscrewing the oxygen sensor from the black dome and holding that over the CO analyzer dome. It worked, but didn't seem 'correct'. I was considering different size tubing and adapters to step the hose barb on the adapter to a hose that would fit into the Analox dome, like the bump test straw :headscratch: .



Then this idea surfaced:

The straw fits snugly right into the barbed end of the BC adapter!!!




Even better:

The vinyl hose fights right over the straw. I just have to pull the hose off the barb, and instantly, it's ready to test CO. I'm rather pleased with myself, lol. The best part is this requires no additional equipment, or even modification of existing items. Oh yea, no more cash outlay either.

I like using the adapter because it restricts the flow to a very low level, wasting little gas. If your BC and reg is already installed by the dive op, you don't need to disconnect the reg. The Quick Disconnect on the BC hose is simple, just remember to double check your inflator after the gas checks, to insure proper operation.

 

[DandyDon]

Don't stick the hose in so deep as to hit the sensor...!

 

[Peter_C]

Does the black part you are supposed to press against the tank on the CO analyzer unscrew? I have always wondered if the Analox units could use the BC adapter screwed directly on. One BC adapter into a Y fitting would allow you to test both at once easily.

The Quick Disconnect on the BC hose is simple, just remember to double check your inflator after the gas checks, to insure proper operation.

Hopefully that is part of the dive buddy checks BEFORE even getting into the water.

 

[TomZ]

Don't stick the hose in so deep as to hit the sensor...!

No worries Don, I don't think you CAN push the straw in deep enough to hit the sensor. I tried. Closer inspection of the dome reveals a stepped hole. The actual hole leading to the sensor is very small. There is no way you could hit the sensor. Luckily for me putting the straw there is idiot resistant.

Does the black part you are supposed to press against the tank on the CO analyzer unscrew? I have always wondered if the Analox units could use the BC adapter screwed directly on. One BC adapter into a Y fitting would allow you to test both at once easily.

The Analox dome is a push fit with an 'O' ring. I considered a 'Y' set-up, but figured juggling the two testers wasn't going to work. However, if you slightly enlarge one of the two holes in the Oxycheq dome, the bump test straw would fit into it, then you could push the other end of the straw into the Analox dome. If you can figure how to manage the two testers, this would enable simultaneous testing.

Hopefully that is part of the dive buddy checks BEFORE even getting into the water.

Absolutely. Just wanted to make sure no errors were made from my advice.

 

[DandyDon]

No worries Don, I don't think you CAN push the sraw in deep enough to hit the sensor

Neat looking rig. It's good to check every tank for O2 as well. I have seen divers who thought they were air who had been on 36% on a deep dive.

I just combined some recent posts into one comprehensive update if you'd like to see it: http://www.scubaboard.com/forums/ba...9-carbon-monoxide-tank-risks-protections.html

 

[TomZ]

Neat looking rig. It's good to check every tank for O2 as well. I have seen divers who thought they were air who had been on 36% on a deep dive.

I just combined some recent posts into one comprehensive update if you'd like to see it: http://www.scubaboard.com/forums/ba...9-carbon-monoxide-tank-risks-protections.html

Good info Don. Being a n00b, I'm really glad I stumbled onto the Analox unit. Piranha had it for a good price just before Christmas. Maybe if these units become more popular, the price will drop.

 

[02HOG]

This looks interesting but for those of us who are not DIY able is there a single device out there that can be used for both CO and Nitrox testing?

 

[DandyDon]

This looks interesting but for those of us who are not DIY able is there a single device out there that can be used for both CO and Nitrox testing?

That idea comes up from time to time, reminding me how when answering machines were common and could be combined with a portable phone base - I always kept them separate so I'd only have one break down at a time and in need of replacement. It would require two sensors of course, separate settings, etc. They might but I don't see it.

You can special order low range analyzers at some manufacturers that can deal with 2 gases, your choice, but it's pricey. I think someone found an O2-CO combined unit on another thread, but it was larger that the Pelican box I carry my two sensors in and cost more.

For the best deal on the 2 units, you might look at this thread: http://www.scubaboard.com/forums/analox-analysers/414979-best-deal-new-post.html

 

[TomZ]

Don,

I asked one of the Oxycheq people about a dual CO/02 analyzer. It seems having the two sensors in close proximity sets up a RF electromagnetic field that causes interference between them. He also said the voltage requirements for the two sensors were different, causing a different set of problems. I suggested a bridge rectifier circuit for the power problem, and posed some ideas about RF shielding, but he didn't seem interested.

 

[koozemani]

Thanks for the thread.