Author Topic: Carbon Monoxide  (Read 1035 times)

Offline ontariomike

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Carbon Monoxide
« on: May 11, 2017, 02:22:39 PM »
I've just completed my version of Sandy Campbell's 3 1/2 inch horizontal boiler. The smallest drill I have is a #78 .016 diameter for my jet. My carbon monoxide detector alarm started an hour after I ran it. It seems like I'm getting incomplete combustion? I'm using Sandy's burner design which works well, I get steam in about 10 minutes. I'm near Windsor Ontario and don't know where to get a smaller jet to see if that is where the problem is coming from.
Any suggestions will be appreciated.

Mike
« Last Edit: May 11, 2017, 07:00:58 PM by ontariomike »

Offline steamboatmodel

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Re: Carbon Monoxide
« Reply #1 on: May 12, 2017, 12:03:54 AM »
Hi Mike,
Can you get more air into the mix?
I pinch most of my gas jets from camping equipment, so don't know what size the hole is.
Gerald.
« Last Edit: May 12, 2017, 12:08:16 AM by steamboatmodel »
Be wary of strong drink. It can make you shoot at tax collectors--and miss. Lazarus Long

Offline SandCam

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Re: Carbon Monoxide
« Reply #2 on: May 12, 2017, 12:24:33 PM »
I've just completed my version of Sandy Campbell's 3 1/2 inch horizontal boiler. The smallest drill I have is a #78 .016 diameter for my jet. My carbon monoxide detector alarm started an hour after I ran it. It seems like I'm getting incomplete combustion? I'm using Sandy's burner design which works well, I get steam in about 10 minutes. I'm near Windsor Ontario and don't know where to get a smaller jet to see if that is where the problem is coming from.
Any suggestions will be appreciated.

Mike

Hi Mike,

It's nice to see another member building one of my designs albeit with a few small alterations, however, there appears to a couple of issues which need addressing.

Gerald is quite correct... you need a LOT more air in the mix as things stand at the moment.

Trouble is that is not really possible with the current burner design.

The main problem is your gas jet is far too big... the burner was designed to use a number 8 'Colman' gas jet which has an orifice of 0.25mm (0.0099") which will allow 108gm/hr to flow through at 20psi.

Your 0.4mm (0.016") would allow around 288gr/hr to flow at the same 20psi pressure.
This is approx 2.65 x as much gas and would require the same proportion of additional air to get the Primary air/gas ratio correct... and that can't happen with the existing burner design.

Unfortunately, neither is it just a matter of turning down the gas feed valve since the flow rate through a given jet dia also dictates the gas stream velocity... and this velocity governs the amount of Primary air drawn in via the side holes in the jet tube (Venturi effect)... I.E turning down the feed to your large jet would also reduce the stream velocity to a value too low to draw in the required Primary air... NET result a very rich mix.

Correct Primary gas/air mix (ratio) is vital or the burner will never operate correctly... it is not just a matter of introducing more Secondary air (via the holes around the outer burner body) either... if the Primary gas/air mix (ratio) is incorrect to begin with no amount of Secondary air will correct the problem.

Looking at your posted photo/picture I also notice that you have installed the jet tube IN-LINE with the burner body rather than at 90degrees... this also will have an effect, albeit less dramatic, on how the gas/air is mixed prior to reaching the underside of the ceramic element... at 90 degrees the gas stream would swirl around the chamber beneath the ceramic, thus mixing air an gas more evenly, whereas In-Line would direct the stream directly at the centre of the ceramic with minimal mixing... thus, potentially, adding to the problem and possibly an more uneven burn pattern.

I would advise you firstly to reduce the jet size to the correct Number 8 size since this will at least get the Primary air/gas proportions in the correct ball park and, secondly, also to consider mounting the jet tube at 90 degrees to the burner body which will certainly improve the gas/air mix issue.

The gas jets I use (as do the majority of UK/EU manufacturers and at least 1 American company) were originally manufactured by 'Calorgas' who eventually sold their camping gas division to 'TAYMAR'...... who were then bought out (taken over) by 'COLEMAN'.... an American company.

These gas jets are available (mail order) from the following (amongst others): -

www.roundhouse-eng.com

www.polymodelengineering.co.uk Then look under the 'BRUCE ENGINEERING' section.

sizes commonly available are: -

                                                                                        flow at 20psi gm/hr

Number 5 which has a 0.2mm dia jet bore                                      68                       

Number 8 which has a 0.25mm dia jet bore                                   108

Number 12 which has a 0.3mm dia jet bore                                   156

Number 16 which has a 0.35mm dia jet bore                                 213

All jets have 1BA thread.

The NUMBER system shown is still used in the UK/EU since this ties in with the original 'Calorgas' numbering system.
and you Know how us Brits just hate to change things...

I hope this helps you overcome the Carbon Monoxide issue.

If I can be of any further help feel free to contact me here, or directly via PM or email.

Best regards.

Sandy. ;D

Offline ontariomike

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Re: Carbon Monoxide
« Reply #3 on: May 12, 2017, 12:34:02 PM »
Thanks for your quick response Sandy. I'm going to follow up on your excellent and detailed advice and will let you know how it works out.

Mike :cartwheel:

PS I just ordered the #5 and 2 pieces of the #8 jets from Mini Steam. My cost with over $39 shipping and exchange on the Canadian dollar is over $95. Still cheaper than poisoning my self. eh
Regards
Mike
« Last Edit: May 12, 2017, 01:07:47 PM by ontariomike »

Online Jo

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Re: Carbon Monoxide
« Reply #4 on: May 12, 2017, 02:38:00 PM »
Silly question: You are using that burner in a well ventilated area aren't you?

If you are not it would account for the CO alarm going off and you will not get the burner mix right  ::)

Jo
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Offline Steamer5

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Re: Carbon Monoxide
« Reply #5 on: May 13, 2017, 01:13:38 AM »
Hi Sandy,
 Following along with Mikes trials & tribulations, besides being thankful that I'm sitting down on reading the postage, & I thought we paid thru the nose!, I was wondering if rather than a 90 degree bend to do the mixing is it possible to include a mixer in the primary gas flow?
Sorry can't recall your drawing so was thinking of something that would allow the burner to be in a line.

Cheers Kerrin

PS Mike, interesting to hear that you have a CO detector in the shop
Get excited and make something!

Offline ontariomike

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Re: Carbon Monoxide
« Reply #6 on: May 13, 2017, 12:41:17 PM »
Carbon monoxide detectors where mandated by the provincial government here in Ontario a few years ago. I had to purchase one and stuck it on a kitchen shelf years ago and forgot about it. My shop is well ventilated and it took me a while to figure out why this alarm kept going off. It gives a digital reading and I could watch the count going up when I placed it by the boiler. When my new jets arrive I'll test it again.

Thanks
Mike