Nitrox users-- do you own an O2 analyzer/meter?

[DA Aquamaster]

I purchased an Analox, because it does not require a flow meter, and is water and shock "resistant". (nothing is water and shock proof). Let face it, it will be used at or near water, and often on the deck of a boat where it will be dropped. So getting one that needs to be babied just did not make sense.

I agree with you that if it around a boat it will get soaked and banged around but that if you have an analyzer you need to have it with you.

One option if you go with a less expensive and less water and shock proof model is to keep it in a padded waterproof box. My ECII lives in a 6" by 9" Underwater Kinetics box. It is kind of a snug fit but is still small enough to throw in the dive bag with the rest of the dive gear and the cost is only about $20-$25.00.

 

[DA Aquamaster]

Saving the money with a DIY kit sounds awefully tempting. I'm no electrical engineer, but I'm pretty handy. Are they as reliable as the ready-bought models?

Many commercial models use the same sensor and the kits are just as reliable and just as accurate (within 1%) as most commercial models. They are however not always quite as easy to calibrate. Some commerical models either auto calibrate or calibrate with a push of a button without having to be connected to a separate 21% or 100% source. In contrast the PM128 based kit analyzers require some user adjustment of the potentiometer.

Ideally I calibrate my EC II off a tank of 21%, but I can also calibrate with the sensor exposed to the open air if I do not have a known tank of air available. With the sensor connected to a tank, there is a slight increase in pressure at the sensor with the Expedition style restrictor and sensor attachment. So when calibrated at 20.9% it will then read 20.6% in open air with the lower ambient pressure. So if I calibrate with the senor exposed to the open air, I adjust the potentimeter to read 20.6 rather than 20.9. Point 3 is not a lot of difference at 21% but it adds up to a percent or two difference when testing deco mixes of around 50%.

So in short, they can have some eccentricities that you need to be aware of, but then after building it yourself, you are also more knowledeable about how it works and knowledge is not something that you can get from just opening a box.

 

[bedmund]

The one I use is the one I build from Oxycheq plans a couple of years ago. Works great and was very easy to construct. However right now it needs a new sensor. :33:

 

[Dive-aholic]

I'm still not seeing the point of spending upwards of $200 for an analyzer unless all you dive is nitrox. And I don't think it's necessary to always dive nitrox. Not all dives are worth the extra cost of O2. Is it worth paying $10 extra for 5 more minutes on a dive? Sometimes it is, but not often. But that's a discussion for another thread. You need to evaluate how much use you'll get out of it to see whether the cost is justified or not. If we're diving under 60', we'll usually run out of air before our NDL is up, and the extra few minutes doesn't justify the added expense. We've even planned multilevel wreck dives starting at 90 feet and nitrox only gave us a few more minutes at depth, a slight ascent gave us more. Again, not worth the $10 extra per tank, at least not on that particular wreck. You just need to evaluate the type of diving you'll be doing and decide whether you need the analyzer more or something else more.

If a LDS is selling nitrox, they should have analyzers available. Mine does, and all the records are in the nitrox log book, which is required to be filled out. If I walked into an LDS to get nitrox and they didn't have an analyzer, then I wouldn't do business with them, at least not with nitrox. I also calibrate their analyzer to the room air and with a tank filled with plain air.

I wouldn't mind owning my own analyzer. I just have other toys I'd rather have first. However, I will definitely be looking into the DIY models. $100 is easily justified.

 

[miketsp]

I own an analyzer and I have been in situations where mine was the only one available to a group of divers. All of the other divers assumed that the boat would have one and when it did not I used mine, and let the other divers on the boat use it as well. If I had not had mine we all would have been in a less than ideal position.

I built mine from a kit at RC Dive Technology kits are available from other sources as well.
..snip..

I'm not too sure I would be happy about lending a home-built analyzer to other divers even if I had faith in it for my own use.
The complications in the eventuality of an accident with any of the other divers could be a real pain even if in the end it was proved that the analyzer was correct.

 

[bedmund]

I'm not too sure I would be happy about lending a home-built analyzer to other divers even if I had faith in it for my own use.

The duct tape on mine usually causes others on the boat to think twice about asking to borrow it.

 

[miketsp]

The duct tape on mine usually causes others on the boat to think twice about asking to borrow it.

Nice technique to discourage interest. A friend of mine does the same with a top end digital camera. It's all covered in bits of duct tape & insulating tape. Even a thin strip across the main display as if it was cracked. It makes it look really old and smashed up. Even though he's been robbed a couple of times, the thieves didn't even think of taking the camera.

 

[scubadobadoo]

I'm still not seeing the point of spending upwards of $200 for an analyzer unless all you dive is nitrox. And I don't think it's necessary to always dive nitrox. Not all dives are worth the extra cost of O2. Is it worth paying $10 extra for 5 more minutes on a dive? Sometimes it is, but not often. But that's a discussion for another thread. You need to evaluate how much use you'll get out of it to see whether the cost is justified or not. If we're diving under 60', we'll usually run out of air before our NDL is up, and the extra few minutes doesn't justify the added expense. We've even planned multilevel wreck dives starting at 90 feet and nitrox only gave us a few more minutes at depth, a slight ascent gave us more. Again, not worth the $10 extra per tank, at least not on that particular wreck. You just need to evaluate the type of diving you'll be doing and decide whether you need the analyzer more or something else more.

If a LDS is selling nitrox, they should have analyzers available. Mine does, and all the records are in the nitrox log book, which is required to be filled out. If I walked into an LDS to get nitrox and they didn't have an analyzer, then I wouldn't do business with them, at least not with nitrox. I also calibrate their analyzer to the room air and with a tank filled with plain air.

I wouldn't mind owning my own analyzer. I just have other toys I'd rather have first. However, I will definitely be looking into the DIY models. $100 is easily justified.

I agree. It really depends on how often you plan on using Nitrox. Heck, I got Nitrox certified to dive "longer" in GC and the boat I was on didn't allow nitrox. If you have never been to GC, it's really easy to get extremely deep, very quickly with no bottom and some ops don't want to use nitrox (even with experienced divers) because of the obvious danger involved.

For some, even getting nitrox certified doesn't make sense. One can even argue that the added safety margin with nitrox is only theoretical, but I am sure I will get flamed on that one. If it exists, it is only fractional. The fact is, from what I have read and learned about nitrox, the same amount of people get bent using nitrox on nitrox tables as get bent on air using air tables. Nonetheless, I'll use nitrox and assume that the theoretical safety margin exists. It certainly makes perfect scientific sense.

Interesting quote from the PADI Nitrox manual...""It's innacurate, however, to suggest that enriched air is safer than air." :11:

Also from the same manual..."There is some risk reduction (mathematically)...but probably not a realistic, significant safety improvement from a practical point of view."

Or this one..."..reducing nitrogen is unlikely to produce a meaningful safety improvement." :06:

A ton of these quotes can be found on page 4, but pay for your course BEFORE you read the manual or YOU might not take it. Just Joking!

However, using nitrox certainly has a more immediate risk involved and that is a strong argument for owning your own analyzer...But I guess MY POINT is that if it isn't worth it for some to get nitrox certified then it certainly isn't worth it for most to have an expensive analyzer.

Just some thoughts regarding nitrox, risk, and the ADDED cost of a fractional safety advantage.

 

[Uncle Pug]

The DIY analyzers are just as good as the commercial versions. All they are is a volt meter. They read the volltage level of the sensor (the expensive part that needs to be replace every two years) and that is calibrated to represent O2 percent. The greater the fraction of O2 the higher the voltage the sensor will produce and the higher the reading will be. Very simple really.

That said.. I can't see any reason for most folks to buy, build or carry their own analyzer much less analyze gas just before the dive. If you are mixing it yourself then you will have an analyzer and have analzyed and labelled your tank ahead of time. If you are like most folks and buy your gas fills then you will have to analyze it at the shop using their analyzer and sign the log book showing that you have done so and then label the tank. If you are on a boat and they are supplying the tanks then you would analyze and mark your tank when you receive it. If the shop or boat where you a getting your nitrox doesn't have an analyzer with a fresh sensor then you probably shouldn't be getting nitrox from them in the first place.

If you are cutting your profiles so closely that a percent one way or the other makes a difference then you are cutting your profiles too close IMO!

 

[MyDiveLog]

I trust my local dive shop, and know that they have a well maintained analyzer that I can use to check Nitrox mixes. This, however, wasn't the case on a dive trip about a year ago -- the time when I most want to dive Nitrox to get in as many dives as possible. The dive resort took FOREVER to find their Nitrox analyzer and, when they did, everyone had to queue up to use it, wasting a lot of time. Some of the divers brought their own (I didn't have one then), and were able to skip the whole hassle. I bought one basically for trips, keeping it in a helium-filled bag between trips to prolong the life of the analyzer.