Continued Carbon Monoxide - Cozumel
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OP
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Fascinating Iya, thanks! Some of it beyond me, but it's nice to read about quality work being done by someone who knows what's going on.
I think I read somewhere in some of these discussions that the Toxirae 3 has a two year life expectancy, altho you may well get more than that as closely as you watch you equipment. I think that CO sensors are commonly rated to 5 years nowadays. I don't have my Anaox CO analyzer yet but it certainly looks promising and I suppose the sensor is as easily replaced as in the O2 analyzer with the same body.
I spoke with Patti at Analox in California today and they are out there after selling all they took to Dema, until Jan 4. When you have someone coming that way from the states, you may want to see about having one brought to you.
I think I read somewhere in some of these discussions that the Toxirae 3 has a two year life expectancy, altho you may well get more than that as closely as you watch you equipment. I think that CO sensors are commonly rated to 5 years nowadays. I don't have my Anaox CO analyzer yet but it certainly looks promising and I suppose the sensor is as easily replaced as in the O2 analyzer with the same body.
I spoke with Patti at Analox in California today and they are out there after selling all they took to Dema, until Jan 4. When you have someone coming that way from the states, you may want to see about having one brought to you.
RubberDucky
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Check this post from the Shopping for Carbon Monoxide (CO) tank testers thread:
http://www.scubaboard.com/forums/5332656-post15.html
Also, the "Specifications" section of the EII CO Carbon Monoxide Analyzer page on the Analox website lists something similar for their device:
Code:
Sensor warranty: 1 year
Electronics warranty: 2 years
OP
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Thanks RD. One major difference is the sensor for the Analox unit is probly user replaceable, while the one for the Toxirae 3 is not - but I really expect actual life on modern sensors to be more like 5 years with calibrations.
The ToxiRAE3 sensor can be replaced, I must send it to Singapore though. The QRAE2 sensor I can do my own replacement. Technically if it is only soldering, its a piece of cake. RAE has another small one, its called T2, which is a disposable unit. BW I think has disposable one too.
I paid US$185 ( I think ) for ToxiRAE3 FOB Singapore. What you need to do is to order fresh stock. Once the unit has the sensor installed and powered, technically its a 2 year life. RAE 2 years is based on this, as told by the techie in Singapore :
-8 hours shift a day. Belt worn at work location.
So assuming 260 days a year at work location, its 4,160 hours burn-out life, which is OK for me.
I got Nitrox/Oxygen meter from Swiss by Eumis, its called Oxy-Spy. They do not install the sensor when shipping the unit. User must install it.
The CO sensors either plays with voltage variation, current variation or resistance variation that is all to it.
Resistance Variation Type :
http://www.appliedsensor.com/pdfs/CO_AK01.pdf
Current / ampere variation , micro amps :
http://www.kwjengineering.com/wp-content/uploads/2008/05/rco1000-rco1000f.pdf
Take note on the spec sheet on LOWER DETECTION LIMIT & RESOLUTION. It stated
" depends on circuitry". I am not surprised this sensor manufacturer stated that fact. This is 0.1 micro ampere ( μA is a millionth of an ampere ) per 1 PPM of CO. I bet making the circuit for the display part for this detector is not going to be cheap.
Current / ampere variation, common 4-20mA
Carbon monoxide sensor CO
Current or voltage type output :
http://www.titanproducts.com/download/datasheets/145.pdf
Few methods for CO detection :
http://www.cambridgeconsultants.com/downloads/library/jwh_publication.pdf
Unfortunately I do not know what type of output is my RAE sensor using.
If one is so anal about precision, one must also calibrate the electronics and not only do sensor replacement. All measuring instruments must be calibrated after a certain time. The sensor is only 50% of the system but the most "unstable" one that is.
Why I like products like RAE is because it has a filter before the sensor. Cross contamination is an issue for industrial environment, for divers maybe not so a problem but its is good to have that filter because :
AA. 2-stroke outboard engine is a dirty bastard, especially the older non high pressure fuel injection type ( Johnson Etec and Mercury Optimax are high pressure 2 stroke ). I do not know Mexico law but poor country ( same as Indonesia ), don't expect stringent clean air act like California.
Combustion engine exhaust will contaminate sensor :
http://www.raesystems.com/~raedocs/.../AP-222_CO_Detection_for_Engine_Companies.pdf
Page 1 : CALIBRATING CO SENSOR, right side of page. Sorry I am unable to copy and paste the summary. I am an IT dummy...
BB. Diesel engine, lots of soots and particulate.
CC. Any flybridge boat with a stern cockpit, say like a typical Viking 60 footer sportfish, will produce a noticeable station wagon effect when boat is trying to plane. Diesel fume will circulate at stern cockpit at that sub 12 knots vessel speed.
Yes, keep any kind of CO or 02 detector in a dry box and do not leave hanging in ambient air.
Another thing I like and honestly it is more troublesome to use, is the BCD type clip airflow limiter/regulator. We are trying to find very low level of CO. Say 3 PPM, that is 3/1,000,000.
A belt worn ToxiRAE 3 will read surrounding CO level at whatever the ambient atmospheric pressure is. A calibration cup is given and it has a bleed hole. One need 0.5 to 1 liter per minute airflow into the sensor, if one is to accurately sense a diver's tank. That bleed hole is designed to allow air flow to discharge and not increase partial pressure.
In any measuring situation, repeatability is the most important value. Even though the sensor already 'drifted", the reading will stay at that drifted level if the test procedure can be done the same way at all times. Calibration will take care of this drift.
What we do not want is an erratic reading. One need to remove the possibility of any inaccuracy caused by variation in the testing method.
Analox stated this in the EII CO owner manual :
WARNING
Very high flows may pressurise the sensor and inaccurate readings or sensor damage will result.
This shows that the sensor will re-act to higher partial pressure. Too much pressure will "pancake" the sensor too...
.
I also have the Analox O2EII , it uses the same method for sensing air as the CO cousin, that half ball thingy with a hole. Opening a tank valve to get a flow going but one will not get the same air flow at all times. FOR CO READING, I prefer BCD clip flow limiter mini regulator, more work but should be better repeatibility. Since the test is all about safety, 60 seconds extra work is no big deal. The result is what we are after.
What I would like to own ( my dream ) is a CO detector that has these features for a wall mounted unit and a portable one :
WALL MOUNTED & PORTABLE
- Filter for cross contamination. All my RAE has this.
http://www.raesystems.com/~raedocs/App_Tech_Notes/Tech_Notes/TN-121_CO_Sensor.pdf
WALL MOUNTED
- 0.5 to 2 micron particulate micron filter from Swagelok, I already have this to protect my dew point sensor.
Tee-Type Filters - Swagelok
To why I insist to have such fine filter is because a filter cartridge of any compressor on its own, only has that filter patch ( the round one ) as particle filter and that is probably not any tighter than 20 micron. My Bauer P41 uses foam type not cloth type filter patch and I am sure its no better than 20 micron too. To why I am so paranoid about particle filtration is because of the nature of the filter media itself, that 13X molecular sieve and whatever dust activated carbon will produce/introduce into the air stream.
13X when over saturated will "foam". I did some testing. I kept 5 spent Bauer P41 cartridges in my office, just keep it on the floor. Initial intend was to measure water content in grams when a spent filter is being kept exposed to 80% humidity for a long time. So I got extra weight from the filter over time, that is good news because that meant my filter cartridge is not 100% "dead" when I removed it from service. What I later discovered is the 13X foaming up as per attached photos. This according to Bauer techie is the root cause of Bauer's PMV ( pressure maintaining valve ) failures.
I asked this question 15 over years ago during a simple Bauer technical seminar :
" What is that white powdery stuff stucked and corroded my PMV internals....I tot it was salt but I licked it and it wasn't salty..."
He said : " You dumb a$$, that is the media over saturated...
"
The dumb ass part was a joke guys...hahahha. This was the time when Bauer User Manual was probably not having temperature compensation information very emphasized. I recalled Bauer P21 ( P Zero ) has rather fantastic tank filling capability as per manual , back then.. and the practice of using a baby P21 for 80 tank fill at 30C ambient were so common. No smell means......keep pumping...hahahah.
Later I discovered that a wetted activated carbon can juiced out sulphuric acid.
This is my #1 suspect for the corrosion of the PMV. That 13X "foam" by product did not corrode my P41 filter cartridge aluminum body.
Why I will be using a Swagelok 2 micron filter later during my compressor mod is because of this "foaming" of 13X and potential dust. I will not over-used my filter cartridge for sure, but cleaner air is always better. If one look at 13X safety data sheet, one will see that potential dust also exist even when it is not water vapor saturated, same as activated carbon. How good a dive regulator 1st stage sintered filter at caching those possible dust, I don't know. I am sure it is not all the way down to 2 micron because pressure drop or flow resistance will be high at such fine filtration and at such high pressure.
Back to wish list :
- Sensor sensitivity as used in Analox wall mounted CO detector, it is a 1-10PPM sensor.
The logic is simple. Lets use the 4-20mA sensor output as the reference. Assume output is linear. 16 milliamps represent the sensor maximum CO sensitivity values in PPM.
For a 10 PPM sensor, that is 1.6 milli amps per PPM of CO.
For a 500 PPM sensor, that is 0.032 milli amps per PPM of CO.
Surely it is easier to be more accurate over the years on the display side of the design to have a 10 PPM sensor instead of a 500PPM one.
Sensor used in the portable Analox EII CO is 1-50PPM, this is also a very tempting specification.
PORTABLE CO DETECTOR and if possible WALL MOUNTED DETECTOR
- Must be IP67 rated like my ToxiRAE3, not like the Analox EII CO which I suspect is IP65 at best. IP67 means 1 meter submerged for 30 minutes, waterproof standard.
We divers are in water world for God sake, IP68 if possible will be a treat.
IP65 unit when it fell, say into a camera fresh water rinse box means good-bye.
The other beauty of IP67 is it is more or less gas tight. Electronics like a CO or 02 detector/meter is basically a digital voltage or amperage meter. One does not need sea water ingress, with the salt laden humidity the sea will throw at you, the copper used on all electronic connection will oxidized and bad or intermittent contact will occur. Either CO values will drift or reading will be erratic. Part of my income comes from tinkering with my client's million dollar yachts and maintaining near-zero voltage loss on a yachts DC electrical system connection, and that is indeed a nightmare, thanks to the evil salty laden high humidity air. If manufacturer can get nitrogen injected into a CO/02 meter and keep it in there like all good binoculars, I will pay extra US$10 for that dry inert gas.
Next will be the filter must be made from Gore-Tex membrane. Gas in .........yes, water in...... no. I will pay extra US$10 for that and this will be a true IP67 rating all the way to the sensor. I think my ToxiRAE3 sensor can not survive 1 meter water immersion, the electronics compartment maybe.
- It must vibrate, produce high decibel alarm and LED/light blinking like my ToxiRAE 3 for alarm. This way we can hang it near a compressor intake when such needs a rise. Multi function it shall be.
Note on IP67 rating. Icom M604 Marine VHF radio ( mounted not portable ) has that rating, its is not difficult to do. A wall mounted CO detector can also be placed on a Live On Board vessel, so its a bonus to have IP67 rating.
Dang, I like to dream of these toys ...
I paid US$185 ( I think ) for ToxiRAE3 FOB Singapore. What you need to do is to order fresh stock. Once the unit has the sensor installed and powered, technically its a 2 year life. RAE 2 years is based on this, as told by the techie in Singapore :
-8 hours shift a day. Belt worn at work location.
So assuming 260 days a year at work location, its 4,160 hours burn-out life, which is OK for me.
I got Nitrox/Oxygen meter from Swiss by Eumis, its called Oxy-Spy. They do not install the sensor when shipping the unit. User must install it.
The CO sensors either plays with voltage variation, current variation or resistance variation that is all to it.
Resistance Variation Type :
http://www.appliedsensor.com/pdfs/CO_AK01.pdf
Current / ampere variation , micro amps :
http://www.kwjengineering.com/wp-content/uploads/2008/05/rco1000-rco1000f.pdf
Take note on the spec sheet on LOWER DETECTION LIMIT & RESOLUTION. It stated
" depends on circuitry". I am not surprised this sensor manufacturer stated that fact. This is 0.1 micro ampere ( μA is a millionth of an ampere ) per 1 PPM of CO. I bet making the circuit for the display part for this detector is not going to be cheap.
Current / ampere variation, common 4-20mA
Carbon monoxide sensor CO
Current or voltage type output :
http://www.titanproducts.com/download/datasheets/145.pdf
Few methods for CO detection :
http://www.cambridgeconsultants.com/downloads/library/jwh_publication.pdf
Unfortunately I do not know what type of output is my RAE sensor using.
If one is so anal about precision, one must also calibrate the electronics and not only do sensor replacement. All measuring instruments must be calibrated after a certain time. The sensor is only 50% of the system but the most "unstable" one that is.
Why I like products like RAE is because it has a filter before the sensor. Cross contamination is an issue for industrial environment, for divers maybe not so a problem but its is good to have that filter because :
AA. 2-stroke outboard engine is a dirty bastard, especially the older non high pressure fuel injection type ( Johnson Etec and Mercury Optimax are high pressure 2 stroke ). I do not know Mexico law but poor country ( same as Indonesia ), don't expect stringent clean air act like California.
Combustion engine exhaust will contaminate sensor :
http://www.raesystems.com/~raedocs/.../AP-222_CO_Detection_for_Engine_Companies.pdf
Page 1 : CALIBRATING CO SENSOR, right side of page. Sorry I am unable to copy and paste the summary. I am an IT dummy...
BB. Diesel engine, lots of soots and particulate.
CC. Any flybridge boat with a stern cockpit, say like a typical Viking 60 footer sportfish, will produce a noticeable station wagon effect when boat is trying to plane. Diesel fume will circulate at stern cockpit at that sub 12 knots vessel speed.
Yes, keep any kind of CO or 02 detector in a dry box and do not leave hanging in ambient air.
Another thing I like and honestly it is more troublesome to use, is the BCD type clip airflow limiter/regulator. We are trying to find very low level of CO. Say 3 PPM, that is 3/1,000,000.
A belt worn ToxiRAE 3 will read surrounding CO level at whatever the ambient atmospheric pressure is. A calibration cup is given and it has a bleed hole. One need 0.5 to 1 liter per minute airflow into the sensor, if one is to accurately sense a diver's tank. That bleed hole is designed to allow air flow to discharge and not increase partial pressure.
In any measuring situation, repeatability is the most important value. Even though the sensor already 'drifted", the reading will stay at that drifted level if the test procedure can be done the same way at all times. Calibration will take care of this drift.
What we do not want is an erratic reading. One need to remove the possibility of any inaccuracy caused by variation in the testing method.
Analox stated this in the EII CO owner manual :
WARNING
Very high flows may pressurise the sensor and inaccurate readings or sensor damage will result.
This shows that the sensor will re-act to higher partial pressure. Too much pressure will "pancake" the sensor too...
.I also have the Analox O2EII , it uses the same method for sensing air as the CO cousin, that half ball thingy with a hole. Opening a tank valve to get a flow going but one will not get the same air flow at all times. FOR CO READING, I prefer BCD clip flow limiter mini regulator, more work but should be better repeatibility. Since the test is all about safety, 60 seconds extra work is no big deal. The result is what we are after.
What I would like to own ( my dream ) is a CO detector that has these features for a wall mounted unit and a portable one :
WALL MOUNTED & PORTABLE
- Filter for cross contamination. All my RAE has this.
http://www.raesystems.com/~raedocs/App_Tech_Notes/Tech_Notes/TN-121_CO_Sensor.pdf
WALL MOUNTED
- 0.5 to 2 micron particulate micron filter from Swagelok, I already have this to protect my dew point sensor.
Tee-Type Filters - Swagelok
To why I insist to have such fine filter is because a filter cartridge of any compressor on its own, only has that filter patch ( the round one ) as particle filter and that is probably not any tighter than 20 micron. My Bauer P41 uses foam type not cloth type filter patch and I am sure its no better than 20 micron too. To why I am so paranoid about particle filtration is because of the nature of the filter media itself, that 13X molecular sieve and whatever dust activated carbon will produce/introduce into the air stream.
13X when over saturated will "foam". I did some testing. I kept 5 spent Bauer P41 cartridges in my office, just keep it on the floor. Initial intend was to measure water content in grams when a spent filter is being kept exposed to 80% humidity for a long time. So I got extra weight from the filter over time, that is good news because that meant my filter cartridge is not 100% "dead" when I removed it from service. What I later discovered is the 13X foaming up as per attached photos. This according to Bauer techie is the root cause of Bauer's PMV ( pressure maintaining valve ) failures.
I asked this question 15 over years ago during a simple Bauer technical seminar :
" What is that white powdery stuff stucked and corroded my PMV internals....I tot it was salt but I licked it and it wasn't salty...
"He said : " You dumb a$$, that is the media over saturated...
"The dumb ass part was a joke guys...hahahha. This was the time when Bauer User Manual was probably not having temperature compensation information very emphasized. I recalled Bauer P21 ( P Zero ) has rather fantastic tank filling capability as per manual , back then..
and the practice of using a baby P21 for 80 tank fill at 30C ambient were so common. No smell means......keep pumping...hahahah.Later I discovered that a wetted activated carbon can juiced out sulphuric acid.
This is my #1 suspect for the corrosion of the PMV. That 13X "foam" by product did not corrode my P41 filter cartridge aluminum body.
Why I will be using a Swagelok 2 micron filter later during my compressor mod is because of this "foaming" of 13X and potential dust. I will not over-used my filter cartridge for sure, but cleaner air is always better. If one look at 13X safety data sheet, one will see that potential dust also exist even when it is not water vapor saturated, same as activated carbon. How good a dive regulator 1st stage sintered filter at caching those possible dust, I don't know. I am sure it is not all the way down to 2 micron because pressure drop or flow resistance will be high at such fine filtration and at such high pressure.
Back to wish list :
- Sensor sensitivity as used in Analox wall mounted CO detector, it is a 1-10PPM sensor.
The logic is simple. Lets use the 4-20mA sensor output as the reference. Assume output is linear. 16 milliamps represent the sensor maximum CO sensitivity values in PPM.
For a 10 PPM sensor, that is 1.6 milli amps per PPM of CO.
For a 500 PPM sensor, that is 0.032 milli amps per PPM of CO.
Surely it is easier to be more accurate over the years on the display side of the design to have a 10 PPM sensor instead of a 500PPM one.
Sensor used in the portable Analox EII CO is 1-50PPM, this is also a very tempting specification.
PORTABLE CO DETECTOR and if possible WALL MOUNTED DETECTOR
- Must be IP67 rated like my ToxiRAE3, not like the Analox EII CO which I suspect is IP65 at best. IP67 means 1 meter submerged for 30 minutes, waterproof standard.
We divers are in water world for God sake, IP68 if possible will be a treat.
IP65 unit when it fell, say into a camera fresh water rinse box means good-bye.
The other beauty of IP67 is it is more or less gas tight. Electronics like a CO or 02 detector/meter is basically a digital voltage or amperage meter. One does not need sea water ingress, with the salt laden humidity the sea will throw at you, the copper used on all electronic connection will oxidized and bad or intermittent contact will occur. Either CO values will drift or reading will be erratic. Part of my income comes from tinkering with my client's million dollar yachts and maintaining near-zero voltage loss on a yachts DC electrical system connection, and that is indeed a nightmare, thanks to the evil salty laden high humidity air. If manufacturer can get nitrogen injected into a CO/02 meter and keep it in there like all good binoculars, I will pay extra US$10 for that dry inert gas.
Next will be the filter must be made from Gore-Tex membrane. Gas in .........yes, water in...... no. I will pay extra US$10 for that and this will be a true IP67 rating all the way to the sensor. I think my ToxiRAE3 sensor can not survive 1 meter water immersion, the electronics compartment maybe.
- It must vibrate, produce high decibel alarm and LED/light blinking like my ToxiRAE 3 for alarm. This way we can hang it near a compressor intake when such needs a rise. Multi function it shall be.
Note on IP67 rating. Icom M604 Marine VHF radio ( mounted not portable ) has that rating, its is not difficult to do. A wall mounted CO detector can also be placed on a Live On Board vessel, so its a bonus to have IP67 rating.
Dang, I like to dream of these toys ...
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Just returned from a week in Roatan at CocoView Resort. Did 14 dives, all nitrox. Two tanks had 1 ppm carbon monoxide, the rest had 0 ppm carbon monoxide. Used my Analox tester. CocoView seems to have a well maintained tank fill area.
OP
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Just returned from a week in Aruba. Did 5 shore dives with nitrox tanks from S.E.Aruba Fly & Dive and tested all tanks for carbon monoxide with my Analox CO analyzer. One tank toggled between 0 ppm and 1 ppm CO, the other 4 tanks tested 0 ppm CO.
divengolf
Contributor
Did Solmar V to Socorro Is. in April with the new Analox CO tester. Most tanks were zero; a couple were 1 ppm. There was a lot of interest from both other passengers and the dive deck crew in what I was doing.
DandyDon: Thanks for all your work on this topic. Plus a big thanks to Patti and Analox for getting this product to market.
Now if we could just get tank fillers to install in line testers.
DAN ought to be all over this.
DandyDon: Thanks for all your work on this topic. Plus a big thanks to Patti and Analox for getting this product to market.
Now if we could just get tank fillers to install in line testers.
DAN ought to be all over this.
OP
- Messages
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It becomes more reassuring that you bothered with the tank checked when you see 5ppm on some tanks - a lot more so when you see 17! Speaking from my limited experiences; I'm sure we'll hear some horror stories this summer.
Speaking from my limited experiences; I'm sure we'll hear some horror stories this summer.I actually talked with the top man there about this. Very pleasant, very agreeable, nothing happened.
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