Diving nitrox when you don't own an analyzer

[Jim Lapenta]

I have owned my own analyzer for a few years now. But I rarely dive nitrox. I do teach the class though and need it for that. Sensors are an issue. I have replaced mine twice. I check the analyzer against a shop's that I use for fills and since they do PP blending will find out when they are mixing for someone and just go down and analyze a few tanks to keep in practice and make sure my unit is working. I built it from a kit. The El Cheapo is a great little analyzer and fun to build.

 

[mala]

Be careful with that. Calibration works for a range. If you calibrate at 100% and then analyze 32% you will not get an accurate reading in that range. Better to just calibrate with 21% to get a closer to accurate reading at 32%. This usually will mean your 100% reading will be over 100%.

if the cell reads 100% with 100% 02 and 21% with air you can assume the readings between are correct.

if you calibrate on air and then get a reading from a tank of 32% all you know is the analyser will read up to 32%.

 

[Token]

If the ean32 is supplied on the boat, the chances are that they will have an analyser you can use. Boats like to have a nitrox fill log hence an onboard analyser. Its worth giving them a call to find out though.

This has been my experience. Unless you're out in the boondocks, any operation you can trust to provide nitrox should have a reliable analyzer.

 

[scubadada]

I have nearly 500 dives on nitrox since being certified in 2002. I have never owned an analyzer. I always analyze the tranks myself or watch it done in front of me and then I always label them myself. So far, so good...

 

[Searcaigh]

Currently I am checking my analyser with air and one of my deco bottles that has 50%

 

[Scared Silly]

While I agree you do not need to own an analyzer but relying on the shop's can be a crap shoot simply because they get used a lot and there is typically only one. I have seen them go belly up and then watched as the shop scrambled to get another. I analyzed our cylinders and those of a couple of other divers who were there but other divers were not so lucky til later that day when the shop got theirs fixed.

For instance, once in Utila they brought NITROX cylinders from their sister shop for us to use but did not have an analyzer. So said they could not give us the cylinders until were analyzed. No problem, I had mine. Another time in Bonaire a half a dozen people were all in line to get their NITORX cylinders for the morning. We were the next three. They were all waiting to use the analyzer then pressure gauge (which also had issues). I had both (plus CO). We were in and out before the first group got theirs done.

Now here is a really good question. When "checking" out a NITROX cylinder you record the O2 contents and most often the pressure. Yet when you get a cylinder with air neither are done. So how many check the pressure with an air cylinder? Conversely how many check the O2 content for an air cylinder that supposedly contains 21%

 

[TSandM]

The El Cheapo is a great little analyzer and fun to build.

Being in the middle of doing so, I would like to offer my take on this: I built Radio Shack kits for years and had a ball. I never expected to receive this kit and discover that you even have to cut the proper holes in the BOX through which to place the display and buttons. Be prepared for a significant DIY project, including cutting accurate holes in hard plastic. It's not just soldering something together.

 

[Drin]

Be prepared for a significant DIY project, including cutting accurate holes in hard plastic. It's not just soldering something together.

I think "significant DIY" is quite often in the eye of the beholder. One large hole for the display , one for the power switch, one for the calibration potentiometer and one for the jack to the O2 sensor. All done with a Dremel in less than 15 minutes.

-Adrian

 

[divengolf]

Good advice here.

If you're going to buy an analyzer, buy a CO analyzer. O2 analyzers are commonly available, but not CO. I've only been on one liveaboard what routinely monitors for CO (the Spree out of Key West), but I've not been on them all. Analox makes a good CO analyzer.

 

[bracko]

I've never seen an operation that didn't have an analyser. it would be a significant risk for any diving operation to hand over tanks without knowing the O2 mix.