I need some gas sensors

[manie]

I have looked at the Futurlec range from the FAReast (or wherever), but they seem to requie heavy calibration work before you can really use them. I do not have such facilities...

I have seen Figaro's site, but can't find where to purchase. These seem to be calibrated and linearised etc, so they should be better, depends on price though. Spark Fun shows only one alcohol(ic), hic !,(shorrie), sensor at US $4.00 or so. Good price.

I require CO(carbon monoxide), CO2, Methane sensors, any ideas where to look ?
Manie

 

[slimplynth]

Hello Manie, had a look around and RS have a few that might be of interest.

 

[manie]

slimplynth: Thanks, had a look on RS, then a post on Discover Circuits where it is said that these Figaro's are not really good for detecting gas as their calibration ALSO needs to be done by hand after building and before using them.... there seems to be very little out there one could use straight out like a temperature sensor.....
Manie

 

[slimplynth]

How critical is accuracy though?

I bought a CO detector last year, LCD screen with alarms and bells etc for 30 quid. Can only hope that the 5 year guarentee is worth it's money wonder who'll get my refund/exchange if this is not the case

There's an animated gif halfway down this page. Looking at it, photoacoustic spectroscopy should be very simple to set up

 

[slimplynth]

In my previous years as a Lab rat, we had to monitor Trike concentrations near a vapour degreasing chamber - using a Draeger pump and tube. They are very accurate if the test is performed properly.
They sell a tube to detect almost any gas you can think of.

The glass tube is around 4 inches long, graduated with a ppm scale. You have to score the sealed tube and snap off the end, insert into the pump.

The pump has a counter on the top that increases by one, with every squeeze. The tubes indicate how many squeezes should be performed.

When you have finished squeezing the tube's contents will have changed colour along the length, dependant on the concentration measured.

It would require some imaginative tinkering to picaxe the above .

They also sell this which looks like the dog's dangleys but you just know it's gonna cost ya when they say "telephone our sales department for a price"

 

[Andrew Cowan]

Depends how much you want to spend and the accuracy.

I'm about to order some of futurlec's modules for a high/low indication.

A

 

[manie]

Andrew: I don'treally know about the implementation of these sensors. What is threshold for "normal air" and at what level do you trigger the ventilation system etc. ? If that is easy to ascertain then accuracy in % is of no consequence. All you want is to prevent the chicks getting smothered !!!!! Ventilate, if level/s are down then start maintaining temperature again... Its only a safety feature to prevent dead chicks due to inadequate ventilation because its cold outside... have I explained it OK ?
Manie

 

[Andrew Cowan]

Fair point - you are talking about living things, so it is a tad more important. As they give an analogue output I plan to measue the vale for 'normal air' at switch on. If the analogue value goes up, then levels have risen. However, for living animals, I can see why a calibrated system (or at least a very reliable system) is important.
A

 

[eclectic]

@Manie
Using the RS link from slim's post #2.

The Methane module NGM-2611 is calibrated, and cheap.

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=5389948

http://docs-europe.electrocomponents.com/webdocs/0660/0900766b80660dc3.pdf

The Carbon Dioxide model, 4161, is calibrated, and more expensive.
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=5389897

(How much is a shed-full of chooks worth?)

Could you use the two gases as “indicators”, of general air condition?
(Obviously basing threshold values on Veterinary advice)

e

 

[manie]

EC: You would only require to have a "fairly" good trigger point to ventilate for clean air, regardless of what temperature state is. Chicks get cold for a couple minutes while you exhaust/inhale, then they get warm again from body heat. At what analogue sensor value do you trigger if you "calibrate" a starting point in known fresh air. If I establish that then the futurlec sensors are perfect. They have cheap LPG one also that can monitor the gas fired heater for gas leaks. Probably best to just get some and set a "mid-point" trigger value. At least you monitor "something" as opposed to NO GAS SENSING at all, which is worst here ?
Manie

 

[slimplynth]

Andrew: I don'treally know about the implementation of these sensors. What is threshold for "normal air" and at what level do you trigger the ventilation system etc. ? If that is easy to ascertain then accuracy in % is of no consequence. All you want is to prevent the chicks getting smothered !!!!! Ventilate, if level/s are down then start maintaining temperature again... Its only a safety feature to prevent dead chicks due to inadequate ventilation because its cold outside... have I explained it OK ?
Manie

Are you planning to calibrate them with ventilation at it's best.. all fans on.. windows open. Suppose you could calibrate for absolute worse case scenario.. by filling bags with the relevant gases.. CO from a car exhaust, vinegar + sodium bicarb for CO2, methane from a cooker.

You're still stuck with the problem of figuring out what the opitimum values are going to be get the perfect balance between temp and air condition.

The RS products look fairly cheap compared to the cost of the chicks, it could be well worth buying several to monitor at different locations.

If all monitoring stations report similar values it doesn't matter what the individual % figures are. You'll soon gather enough consistent data to fine tune your system. Even if you're just monitoring it at first and logging everything, your graphs will show you when the ventillation is on/off and how the data collected from your sensors changed.

 

[manie]

slimplynth: I've ordered CO/Air/LPG from Futurlec along with some other goodies to make the shipping cost worthwhile. I've also thought of just "doctoring" some bags of air and using the old "snozzle" olphac aparatus ("nose-it") as indicator of what is clean/acceptable/bad/lethal and use those figures to trigger events. As at present there is ZERO such refinement in the chook-house and a number of thousands of chicks have been raised, so this can only be an improvement, regardless of whether trigger thresholds are absolutely correct or not. I'll look at the datasheets to see what I can gleen with regard to output level interpretation.... This project is certainly excercising the grey-matter department I tell you, but thats probably why i enjoy it AND WHY DIPPY MAYBE DOES NOT ??? (He has to steer me from time to time and Manuka's heart rate is up and down at times also....)

Nonetheless, we're getting there, V_2_0 PCB will have serin/serout on HSERIN/OUT pins when next I build it for instance. We new guys sometimes DO LISTEN !! LOL LOL LOL
Manie

 

[manie]

The Futurlec CO sensor datasheet (attached) shows pulsing of the heater circuit, but apparently you can just have it ON also. Is there any benefit in pulsing it, besides saving on power input ?

This will determine whether I require an additional 08M to drive this pulsing or not..

Manie

 

[Dippy]

I thoroughly enjoy it.

High/Low? Dunno. probably just for saving power.
It seems that the graph flattens, so maybe they are saying that there is no point measuing longer than 90seconds so save your batteries.
Without playing with one I can't say 100%.
Sounds fun.

 

[manie]

Dippy:

I thoroughly enjoy it.

Explain ? Or is it that natural "sharp" edge getting keen ?

The main problem here is the OVERWHELMING amount (lack)of actual data (facts) on the "data"sheet.... or is it that the active bit on the sensor will get damaged when "on" the whole time ?

Manie

 

[eclectic]

Dippy: Explain ? Or is it that natural "sharp" edge getting keen ?

The main problem here is the OVERWHELMING amount (lack)of actual data (facts) on the "data"sheet.... or is it that the active bit on the sensor will get damaged when "on" the whole time ?

Manie

I think I know what Dippy means,
but I won't elaborate on a public forum. ;-)

And, back to reality, the heater resistance is 33 Ohms.
Watch out for the current!

e

 

[Dippy]

Explain? Umm.. I thoroughly enjoy the Forum and all the interesting and mind-stretching subjects that crop up.

Yes, it is hefty on juice. Most heated ones are.
How are you going to power it? Ideal job for switched mode

There are better ones around but I suspect they won't be cheap.

The Data Sheet is better than the usual Chinese stuff.
And it's certainly enough to 'tease' you into buying one maybe?

I haven't got a clue how much these things cost, but unless you can find someone who has used exactly this device you'll be waiting a long time.

I have only ever used methane etc sensors from Maplin and RS. That was years ago but they had a similar operation. And with those the preheat time wasn't so long. Not sure if they sell that kind of thing anymore.

Buy one. Have a go. Learn, enjoy and then you'll be able to tell others the best way to use it.... and don't forget to calibrate it. Now there's a title for a new thread

 

[Andrew Cowan]

The LPG type from futurlec are the types maplins use to sell. I never got around to playing with them back then, however.

I've ordered an LPG and CO2 sensor aswell, so I'll let you know how I get on.

A

 

[papaof2]

power requirements

The Futurlec CO sensor datasheet (attached) shows pulsing of the heater circuit, but apparently you can just have it ON also. Is there any benefit in pulsing it, besides saving on power input ?

This will determine whether I require an additional 08M to drive this pulsing or not..

Manie

My read of the datasheet graph is that you cycle the 5v and 1.4v heating votages alternately "the high voltage and the low voltage work circularly" and the difference between the signal levels across RL at 5v for 60 seconds and 1.4v for 90 seconds is related to the CO concentration. The reading takes place over a couple of minutes: "output signal measurement is made within one or two complete heating period (2.5 minute from high voltage to low voltage)". Maybe check for 5 minutes (two full heating cycles) every half hour?

Other bits from the datasheet:
- calibration is sensistive to both temperature and humidity
- the calibration procedure requires having the sensor powered for 48 hours

If you have a source of CO and a household CO monitor, you can probably come up with "safe" and "not safe" values - more important for your application than an absolute measurement CO ppm.

With an estimated life of 5 years, be sure to buy extras if you use this device - it may be obsolete in 5 years :-(

John

 

[manie]

With an estimated life of 5 years, be sure to buy extras if you use this device - it may be obsolete in 5 years :-(

Now I really feel better !............. at least in 5 years time, the Picaxe "44yz6" will have these sniffing sensors and functions on-board, Hippy will write the code internally, should you want to use it the command will be something like:

Main:
gosub sniff

goto main

sniff:
w0= #CO
w1=#CO2
return

I can dream can't I ??

Edit:
Thinking of it.... in 5 years time I'll be obsolete too.........

 

[Andrew Cowan]

In 5 years, they'll be a minature hippy inside every chip!

gosub hippywriteprogram

A

 

[manuka]

Just out of interest, what staffing levels (and at ~what pay rates) does this chook house operation require anyway? Could someone with a good nose just be assigned to monitor conditions? Isn't 1200 Rand a month (~US$120) a typical farm labourer's income? That's almost orders of magnitude cheaper than European/US/Australian farm rates- when naturally the incentive to go high tech. can be strong. NZ dairy farms usually only have a couple of (often extremely well paid!) guys milking 100s-1000s of cows twice daily, with milking "sheds" set up more like space shuttles.

I'm naturally not against automation, BUT it's worth keeping things in perspective- especially given such low RSA rates of pay. When local labour is cheap, technical solutions (with their associated specialist overheads) may be an overkill. These high current gas detectors may require heavier duty power supplies, & back up UPS facilities, and ...

Aside from the classic Indian dishwasher misunderstanding (when a cheap human was supplied instead of a costly machine), consider a short term roadworks "STOP-GO" sign man who could be both far more cost effective AND also responsive to unusual traffic conditions than an automated system.

 

[manie]

Stan: Rates mentioned are true (more or less), BUT.... automation does not strike, nor get drunk, nor just stay away, nor fall asleep on the job, nor " I forgot.." once taught properly, nor pull a "W_in-do--'s" on ya and stop for no reason at all, if they do any of the above it can usually be traced/audited/fixed and/or renewed/updated etc...... automation reliability is far superior to human action of the kind suggested, even my home brew one ! Does that make sense ? Anyway, I think you asked, "how much are a couple thosand chooks worth ???"

Manie

 

[slimplynth]

Just out of interest, what staffing levels (and at ~what pay rates) does this chook house operation require anyway? Could someone with a good nose just be assigned to monitor conditions?

I'd guess that stale air detection by a human is very subjective and varies from person to persson - you'd get used to it eventually. Additionally, methane (natural), CO and CO2 are odourless. Methane and CO2 are greenhouse gases so will raise the temperature, which could affect bird egg development and increases the viability of some bird parasites' eggs.

On a tangent, does anyone remember that "You Bet" program in the 90's (UK), hosted by Mathew Kelly.

In a nutshell there were people who claimed to be able to perform extraordinary feats. A panel of celebrity judges had to gamble on whether or not the feat was achievable. One has always stuck in my mind... this French bloke was able to use his nose to tell the temperature of 10 glasses of water, accurate to one decimal point. I doubt he'd be intrested in a job sniffin chicken shhh poop for $120 a month though

 

[Andrew Cowan]

Plus, are you going to have a team of guys on shift 24/7?

A

 

[manuka]

Splutter- for you city boys here's how it goes => the baas (boss man) just trains up a few capable hands & PAYS THEM a decent bonus for the higher tech work. No doubt with such cheap labour (& 20k chooks) the operation has 24/7 staffing anyway, & the status gained by workers would be welcome too.

Footnote: Bumper apple crop in NZ this year, with pickers (many of whom are "imports" from Pacific Islands, as insufficient Kiwi staff) earning ~US$100 daily-most Westerners wouldn't get out of bed for such low gross earnings (before tax, deductions & expenses). It's certainly hard to relate RSA farm worker incomes to this...

 

[manie]

It's certainly hard to relate RSA farm worker incomes to this...

Also hard to relate the RSA farm worker OUTPUTs to this... I'm sure there is no comparison Stan...

Just to straighten things a bit.. In SA, you want as much as POSSIBLE automation, otherwise its a case of "ooooppppssss, sorry..."

 

[eclectic]

@manie.
Just some thoughts from a city dweller.

The Picaxe Canary hack? A possibility?

Self contained CO alarms are cheap.

How about buying a couple, disconnecting the speaker,
then, interfacing the alarm output to a Picaxe?

Caveat. What is the CO susceptibility of Chooks : Humans?

e

Yes I know.
The Canary was for Methane, but it's the principle.

 

[manie]

Andrew, Stan, EC: The CO sensor is only for those winter days/nights (can be really cold) when the gas heater is going. Just monitoring temperature can result in oxygen depletion if you don't "force" ventilate, it has not happened yet but remains a possibility.

Anyways, Futurlec (believe this !!) wants me to fax

a SIGNED copy of my credit card

, HUH ?? since when, do they think I'm daft ? So I'm cancelling the order and buying elsewhere !

Rev-Ed: You don't supply gas sensors maybe, do you ? One thing I can say for sure from down South is, EVERY order from Rev-Ed so far was METICULOUSLY executed and delivered in good time. Well done Tech-Supplies !

 

[eclectic]

Andrew, Stan, EC: The CO sensor is only for those winter days/nights (can be really cold) when the gas heater is going. Just monitoring temperature can result in oxygen depletion if you don't "force" ventilate, it has not happened yet but remains a possibility.

Anyways, Futurlec (believe this !!) wants me to fax , HUH ?? since when, do they think I'm daft ? So I'm cancelling the order and buying elsewhere !

In that case, have another look at posts
2, 4, 9, 11, 28. and possibly others.

Get something that works.
It won't cost as much as 2000 chooks.

e

 

[Andrew Cowan]

I completely misunderstood the scale of this - I assumed it was for 2 or 3 chooks, and thus a $50 is way too much. If you have several hundred, definitely go for a quality, calibrated bit of kit.

A

 

[manuka]

Just several hundred? It's apparently more like 20 thousand! We're talking commercial...

 

[Andrew Cowan]

Definitely worth spending lots on those gas sensors, then.

A

 

[slimplynth]

finger lickin good

Crikey, thats some chicken coup.. do you collect the methane from the manure for energy?

 

[KIGX]

Instead of using solar panels to recharge your remote batteries you can use methane power.

Come to think of it, you could probably just jam a couple of electrodes into the nearest manure pile and run directly off that...

 

[manie]

Like Westy said, its commercial in the early stages. Currently 5000 chicks at a time, will expand to 20 - 25 thousand soon, which means there is 220V power there, so a good power supply is in order, no need to recharge, Picaxe will monitor backup 48AH 12V car batteries to maintain charge levels in case of power outage. (And with Escom's past record, outage is a fact of life in mid-winter !)