"The Best." Oxygen Analyzer?

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Boston Breakwater

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Hello, Everyone. I'm in the market for an O2 analyzer. I have been scouring the Internet looking at different companies. Admittedly, I don't know if one company is more reputable than another, or anything about their customer service?
I will use it for "Nitrox." mixes Typically 24% and 26% ranging up to 50% (Sometimes 80%)
I am generally alone, and sometimes in remote locations, so, I would also like to double check, and verify my Oxygen bottles. (Preferably one that would screw right into the D.I.N. valve.)
I was leaning towards this.
OxyCheq Expedition O2 Analyzer
I would greatly appreciate your feedback..........Personal experience, and recommendations.
Edit. When. I typed "The Best."........I realized there may be models way beyond my necessity. I would like to stay in the $300 - $500.00 range. (If, possible.)
Edit. I would almost expect the reading to go from 0% to 100% (Is that not the case?)
Cheers.
How to Find the Best Scuba Oxygen Analyzer - Scuba Diving Gear

A Must Have for Nitrox Divers: Undercurrent 02/2009

Excerpt.
Analyzer Calibration

A Nitrox analyser has an oxygen sensor that generates a voltage that varies according to the percentage of oxygen present, and gives a readout on a voltmeter calibrated in percentages. An analyzer reading is affected by air pressure (weather) and the aging of the sensor cell, so before each dive, it needs to be calibrated at 20.9 percent O2 with clean air passing around it. If you calibrate using pure oxygen instead of air, the sensor readings will be three times more accurate.

Recently, I was on a liveaboard with a diver who was a gas analyst from Siemens. He merely checked his tank each time to see that he didn’t have air. He told me that the analyzer on board was so inaccurate, it was only good for telling whether you got air or something else, but nothing more. He just checked to see if it went over 21 percent but didn’t bother with a final reading. Furthermore, he said, the little oxygen analyzer that I had held so much faith in was almost totally inaccurate. I was shocked. So what was wrong with the simple equipment that was available to us?

The problem stems from gas flowing over the sensor. He pointed out that the gas had to be stationary or controlled to a known rate. By simply increasing the flow, the apparent oxygen content increased. Cracking open a tank valve “just a little’” and holding the cell over it is evidently not accurate enough for him. Temperature also makes a difference, and gas depressurizing from a tank can be very cold.

Some analyzers use the direct-feed hose to the BC, using the regulator first-stage as a flow control. It takes time to get a reading and this seems unpopular with divers impatient to get in the water. Divers will always look for the most convenient method. I have witnessed Nitrox being analyzed by holding the sensor in the mouthpiece of a regulator while the purge button was pressed.

But manufacturers have come up with designs to get a stationary sample of gas at the same ambient temperature and pressure with which the analyzer was calibrated. Some restrict the flow of gas over the cell while others attempt to capture a stationary sample. It seems that the bit of plastic tube that interfaces between the tank valve and the sensor is very important.

If your Nitrox is made by the older partial pressure blending system, you need to know your analyzer is exact, because there you may inadvertently get very high percentages of oxygen, if by mistake.
 

RogueClimber

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Reading through the Deep Blue Diving article linked above I found this statement:

"4. Make sure the level is where you want it – Many recreational divers make use of Nitrox, which tends to be about 21% oxygen. That said, some mixtures can range from 22% to 40%, so check with the manufacturer to figure out whether your reading matches the correct level."
I'm not sure I'd consider their expert advise on anything after reading that....

Analox, Oxycheq, and PalmD are the ones I hear about most often. We use Analox on our boats
 

rjack321

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OP
Boston Breakwater

Boston Breakwater

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grantctobin

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Hello. I've always appreciated your posts. I'm thinking that screwing the sensor into the D.I.N. valve would provide a more "Accurate reading?" Agree, or diagree?
Cheers.
The sensors themselves aren’t accurate enough to notice a functional difference between DIN screw-in, DIN reg inflator hose female to analyzer inflator nipple male, or mushroom held into the valve opening itself. The Divesoft analyzers seem to be a little finicky when it comes to flow rate, but those are out of your stated price range and overkill for your purposes. Aren’t you using a yoke valve on your MOD20 bottle anyway? Or is that your 80% bottle you show pictures of?
 

Rose Robinson

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Hello, Everyone. I'm in the market for an O2 analyzer. I have been scouring the Internet looking at different companies. Admittedly, I don't know if one company is more reputable than another, or anything about their customer service?
I will use it for "Nitrox." mixes Typically 24% and 26% ranging up to 50% (Sometimes 80%)
I am generally alone, and sometimes in remote locations, so, I would also like to double check, and verify my Oxygen bottles. (Preferably one that would screw right into the D.I.N. valve.)
I was leaning towards this.
OxyCheq Expedition O2 Analyzer
I would greatly appreciate your feedback..........Personal experience, and recommendations.
Edit. When. I typed "The Best."........I realized there may be models way beyond my necessity. I would like to stay in the $300 - $500.00 range. (If, possible.)
Edit. I would almost expect the reading to go from 0% to 100% (Is that not the case?)
Cheers.
How to Find the Best Scuba Oxygen Analyzer - Scuba Diving Gear

A Must Have for Nitrox Divers: Undercurrent 02/2009

Excerpt.
Analyzer Calibration

A Nitrox analyser has an oxygen sensor that generates a voltage that varies according to the percentage of oxygen present, and gives a readout on a voltmeter calibrated in percentages. An analyzer reading is affected by air pressure (weather) and the aging of the sensor cell, so before each dive, it needs to be calibrated at 20.9 percent O2 with clean air passing around it. If you calibrate using pure oxygen instead of air, the sensor readings will be three times more accurate.

Recently, I was on a liveaboard with a diver who was a gas analyst from Siemens. He merely checked his tank each time to see that he didn’t have air. He told me that the analyzer on board was so inaccurate, it was only good for telling whether you got air or something else, but nothing more. He just checked to see if it went over 21 percent but didn’t bother with a final reading. Furthermore, he said, the little oxygen analyzer that I had held so much faith in was almost totally inaccurate. I was shocked. So what was wrong with the simple equipment that was available to us?

The problem stems from gas flowing over the sensor. He pointed out that the gas had to be stationary or controlled to a known rate. By simply increasing the flow, the apparent oxygen content increased. Cracking open a tank valve “just a little’” and holding the cell over it is evidently not accurate enough for him. Temperature also makes a difference, and gas depressurizing from a tank can be very cold.

Some analyzers use the direct-feed hose to the BC, using the regulator first-stage as a flow control. It takes time to get a reading and this seems unpopular with divers impatient to get in the water. Divers will always look for the most convenient method. I have witnessed Nitrox being analyzed by holding the sensor in the mouthpiece of a regulator while the purge button was pressed.

But manufacturers have come up with designs to get a stationary sample of gas at the same ambient temperature and pressure with which the analyzer was calibrated. Some restrict the flow of gas over the cell while others attempt to capture a stationary sample. It seems that the bit of plastic tube that interfaces between the tank valve and the sensor is very important.

If your Nitrox is made by the older partial pressure blending system, you need to know your analyzer is exact, because there you may inadvertently get very high percentages of oxygen, if by mistake.

Hello Boston Breaker,

Check nuvair.com and look at the 02 Quickstick, the new model is green in color.
I love mine.

Rose
 

rjack321

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Hello. I've always appreciated your posts. I'm thinking that screwing the sensor into the D.I.N. valve would provide a more "Accurate reading?" Agree, or diagree?
Cheers.
All flow restrictors work the same way (with an orifice). 2L gas across the sensor face and it makes no difference if you use a DIN flow restrictor or a BC nipple, or develop the "knack" for cracking the valve just so. I'm not sure what kind of precision you expect but +/- 1% is all you need anyway. Accuracy is much more dependent on the age of the sensor than on anything else.
 
OP
Boston Breakwater

Boston Breakwater

"Outlaw." Solo Diver
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The sensors themselves aren’t accurate enough to notice a functional difference between DIN screw-in, DIN reg inflator hose female to analyzer inflator nipple male, or mushroom held into the valve opening itself. The Divesoft analyzers seem to be a little finicky when it comes to flow rate, but those are out of your stated price range and overkill for your purposes. Aren’t you using a yoke valve on your MOD20 bottle anyway? Or is that your 80% bottle you show pictures of?
Hello. My dedicated Oxygen 40 cubic bottles are "White." using a dedicated Apeks Tungsten D.I.N. The brushed aluminum dedicated "Nitrox." bottle has an Apeks "Black Sapphire that is an A-clamp. ( I bought it as a collectors item....the box was damaged so badly, I decided to use it.) All of my bottles have D.I.N. valves, there is an insert in the valve to accommodate the A-clamp. A new First, and Second stage (D.I.N.) is coming for the "Nitrox." bottle.
Cheers.
 

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