AnotherThreadAboutCOanalyzers

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Dominick Gheesling

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So I just did some comparisons of different Manufacturer's units as I am going to need a CO analyzer.

I am definitely interested in these Sensorcon units. I've seen some posts recommending them and the price point is very attractive.

Here is what I just found today:

OXYCHEQ expedition: +- 2ppm or +- 1%

NUVAIR Pro CO: +- 5%

Palm CO: +1ppm or +5% after factory calibration

Sensorcon Inspector: +- 10% at ambient conditions

Per DAN: "A realistic standard that is safe, achievable and practical for most divers is 5 ppm. Many inexpensive, portable CO analyzers measure from zero to 25 ppm, with a 1 ppm resolution, making them suitable for detecting safe levels of CO in the dive environment."

Someone please feel free to correct my math as math is certainly not my strongsuit:

If Meter reads 5ppm then:

+1% would be 5ppm x .01 = 5.05ppm (Qxycheq)
+5% would be 5ppm x .05 = 5.25ppm (NuvairPro/Palm)
+10% would be 5ppm x .10 = 5.5ppm (Sensorcon Inspector)


Is the Sensorcon Inspector accurate enough?
 
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rddvet

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In my experience the sensorcon sucks. I got rid of mine. A ton of people on here like them, but I don't know why other than they're cheap. The unit will give false negatives and positives based on flow. It is very finicky and needs the appropriate flow rate to be somewhat accurate. Add to that I believe they have to be calibrated every so often (don't quote me on that as I sold mine 4 years ago). I put mine up against my oxycheq (which imo should be the standard to compare all other units to). I would get wildly different results. I would get 14ppm on the sensorcon, then test again and get 3, then I'd get 0. All the while I would test against the oxycheq (which I keep plumbed into my fill station nromally), which would be at zero. I have a friend that has a tank containing CO (he uses to teach new students the importance of CO testing). I got 5 different readings from 0-30 on my sensorcon. The oxycheq was dead on at 19 every time.
I honestly put no trust in the sensorcons and think they're so finiicky you can't rely on them. When mine was so off, I contacted Sensorcon. It took about 5 emails to get a response. At first they danced around the answer. When I pushed back the rep said that their unit was never intended to be used for diving applications and it was an afterthought when they saw testing was becoming more common in the diving world. So they started marketing them to diving as well. But the rep confirmed to me that the unit was originally meant for ambient air testing, and any significant flow of gas will cause false readings. When I get some time I will search for the email and copy/paste it if I can find it. Everytime I post my experiences with sensorcon I always get push back here from people that think it's amazing.
IMO, buy the best CO tester you can and don't worry about the cost difference. You will likely never find CO, but when you do the unit pays for itself. With the sensorcon, I never felt comfortable enough that I would put my or my wife's life on the line by trusting it was accurate. I'd recommend Oxycheq first, and palm second. I've been running my oxycheq for 9 years now. I sent it back to oxycheq once when it was having an issue. THey changed the sensor and recalibrated as part of the repair and it wasn't overly pricey. Add to that the fact that Oxycheq's customer service is excellent, and it makes them worth it.
 

divinh

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I have a Sensorcon, purchased before going on a liveaboard, because I was potentially going to cabin by the engine room. I was mainly concerned about exhaust leaking in the room, not so much testing the tanks. Upon arrival, they put me in the room at the bow, so I tested and didn't read anything. For me, the Sensorcon's value is in having a portable CO detector when staying at unknown places.

As for using it as a tank tester, most of what I read had to do with using a bag to collect the air and testing it that way. A direct burst of air into the sensor probably wouldn't work as well, as it is designed to test ambient air, as noted.
 

Jack Hammer

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I like the Sensorcon, pretty simple to use and mine have been accurate. It is important to limit flow though or that accuracy is all over. This really shouldn't be an issue for anyone who has used most handheld O2 units that are without a flow limiter. Just crack the valve barely but enough for a slow consistent flow, just like with my O2Eii. Then wait a few seconds.

The Analox was great except the sensors were around $275 and need to be changed every 2 years.

I've had great experiences with the Oxycheq unit too, simple and accurate.

Stay away from the (forget brand name) unit with both O2 & CO that connects to phone. I dont know anyone who hasn't had issues with it.

Haven't used the Nuvair.

Used the Palm, it was ok, I didnt care for it. My friend liked his.
 

DandyDon

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If Meter reads 5ppm then:

+1% would be 5ppm x .01 = 5.05ppm (Qxycheq)
+5% would be 5ppm x .05 = 5.25ppm (NuvairPro/Palm)
+10% would be 5ppm x .10 = 5.5ppm (Sensorcon Inspector)
Yeah, dealing with PPM can be confusing, but your math looks right.

Is the Sensorcon Inspector accurate enough?
For keeping you from getting poisoned, yeah it'll work. It won't be accurate enough to bear witness in a court of law, but you just want to avoid injury or worse.

Leave it on 24/7 so it can also protect you from your hotel room, cabin, car, etc. I got a new one on special last time instead of having my old one refurbished with a new sensor and new battery, but the old one has been on 24/7 for over three years now and still alerts to CO exposure in a closed garage test, as dangerous as that can be. The company claims that the unit's programming will adjust for sensor drift. Maybe it will or won't, but it'll keep you safe enough.
In my experience the sensorcon sucks. I got rid of mine. A ton of people on here like them, but I don't know why other than they're cheap. The unit will give false negatives and positives based on flow.
Yeah, flow rate can give you false readings. I prefer a gallon ziplock.
I think that you have to explicitly write carbon monoxide for @DandyDon to be alerted to the conversation.
Maybe they were avoiding that? :eyebrow:
 

rddvet

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I like the Sensorcon, pretty simple to use and mine have been accurate. It is important to limit flow though or that accuracy is all over. This really shouldn't be an issue for anyone who has used most handheld O2 units that are without a flow limiter. Just crack the valve barely but enough for a slow consistent flow, just like with my O2Eii. Then wait a few seconds.

The Analox was great except the sensors were around $275 and need to be changed every 2 years.

I've had great experiences with the Oxycheq unit too, simple and accurate.

Stay away from the (forget brand name) unit with both O2 & CO that connects to phone. I dont know anyone who hasn't had issues with it.

Haven't used the Nuvair.

Used the Palm, it was ok, I didnt care for it. My friend liked his.

i loved the analox until I needed a sensor too. As for the sensorcon issues, I did it just like I would an oxy analyzer without a limiter. I would check the samples multiple times and found varying results from back to back samples very often. I ended up trying it with a flow limiter which helped alot, but it still wasnt highly accurate so I gave up on it. i specifically bought it for use at dive sites so I wouldnt have to take my oxycheq off my fill station, wo wanted aomething without a flow limiter.
I also used my friend’s co containing tank to do alot kf testing of the sensorcon. When you have tanks with 0 or up to 3 ppm you really dont see the issues since most of the time it’ll show zero. When you test it against a bump gas the varying results becomr very evident.
 

BlueTrin

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So I just did some comparisons of different Manufacturer's units as I am going to need a CO analyzer.

I am definitely interested in these Sensorcon units. I've seen some posts recommending them and the price point is very attractive.

Here is what I just found today:

OXYCHEQ expedition: +- 2ppm or +- 1%

NUVAIR Pro CO: +- 5%

Palm CO: +1ppm or +5% after factory calibration

Sensorcon Inspector: +- 10% at ambient conditions

Per DAN: "A realistic standard that is safe, achievable and practical for most divers is 5 ppm. Many inexpensive, portable CO analyzers measure from zero to 25 ppm, with a 1 ppm resolution, making them suitable for detecting safe levels of CO in the dive environment."

Someone please feel free to correct my math as math is certainly not my strongsuit:

If Meter reads 5ppm then:

+1% would be 5ppm x .01 = 5.05ppm (Qxycheq)
+5% would be 5ppm x .05 = 5.25ppm (NuvairPro/Palm)
+10% would be 5ppm x .10 = 5.5ppm (Sensorcon Inspector)


Is the Sensorcon Inspector accurate enough?
Using the same logic, the thresholds should be:
- 5 /1.01 = 4.95
- 5 / 1.05 = 4.76
- 5 / 1.1 = 4.54

Because if you measure 4.54 + or - 10% then you are anywhere between 4.54 * 0.9 and 4.54 *1.1.

So for the purpose of testing for CO you’d take the most conservative value which is to assume that it would be 10% higher than measured?

Realistically you’d probably discard anything that reads too close anyway?
 

rjack321

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Using the same logic, the thresholds should be:
- 5 /1.01 = 4.95
- 5 / 1.05 = 4.76
- 5 / 1.1 = 4.54

Because if you measure 4.54 + or - 10% then you are anywhere between 4.54 * 0.9 and 4.54 *1.1.

So for the purpose of testing for CO you’d take the most conservative value which is to assume that it would be 10% higher than measured?

Realistically you’d probably discard anything that reads too close anyway?
Realistically anything over zero is cause for concern. You don't splice hair over this, its easy to make gas with NO Co and if any is present that means the fill station is suspect.
 
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