Electronic Flue Gas Analyser

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It’s Original but Not Antique

What you have sounds quite different from what the original designer has described. Have you bought a cheap clone/fake, or one which has been 'got at' by an incompetent 'repairer'?

Please be reassured this unit came direct from Colwick Instruments Limited; I can say that they did bring out a digital version, that’s all I know regarding other versions. :cool:
 
A Good Choice FIGARO TGS812 Now Updated to TGS822

but I would think that a 'CO detector' which actually uses just a combustible gas detector will not be very accurate in the presence of any unburnt fuel.


This sensor is; please checkout post 11 attachment and for further reading the link in post 1, then go to item 6 or 9. ;)
 
That datasheet seems to confirm what I thought. It cannot tell the difference between CO and methane. It is less sensitive to methane, but the basic problem still remains. To give a meaningful CO reading you need to be certain that there is only small amounts of other combustible gases present. The conditions which give rise to CO (poor combustion) are likely to cause unburnt fuel to appear in the flue. Perhaps the instrument makes some assumption about conditions in a boiler and gives a CO 'measurement' by actually measuring total combustible gas in the flue? That is, it is actually responding to methane+CO but in this particular application there is a good correlation between these two different gases?

In any case, it cannot measure CO2 with that sensor so it must do it some other way. The designer says it uses a different sensor for CO2. Is that extra sensor missing from your unit?
 
It is very common for analyzers to calculate (rather than measure) CO2. They usually do it using an O2 measurement in addition to the CO.
Comparing the New Testo 310 and 320 Combustion Analyzers | Ivy Tools Blog

That old meter is not suitable for anything but a collection of antique instruments. Using it for practical measurements and adjusting furnaces is a bad idea and could result in liability issues.
 
Anagas information please

Greetings. I have just acquired a non-working Anagas analyser, No 9268. I wonder whether David Cameron (or any other contributor) has by any chance an electronic copy of the user manual and/or service manual. I have only had a brief look at the instrument so far, but my immediate puzzle is how to gain access to the 'works'. The aluminium plate covering them appears to be pop-riveted down on to something. But there must be some other fastener hiding somewhere. Many thanks.
 
Progress: drilled out previous repairer's pop rivets, and will replace with screws. Insides appear fairly clean and undamaged, except for a little corrosion here and there, mainly on power socket. Removed latter, cleaned and refitted. Secured loose batteries. Now it charges nicely. Pump does not work, despite 10v on motor (with battery on charge). Removed motor end cover exposing worn and corroded commutator but surprisingly un-worn brushes. (See photos.). Plan now to remove armature and skim commutator. Question for D Cameron or anyone else: Is eccentric secured just on a press fit?
 

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Progress again: Eccentric is only a press fit. By clamping eccentric between soft (aluminium) jaws, motor shaft can be pressed or gently tapped out. With commutator skimmed and reassembled, motor works fine now.
Main rotary switch turned roughly and stiffly. Dismantled (carefully spring out 2 plastic hooks to separate body), cleaned and greased (Vaseline) rusty ball and spring detents, reassembled. (Dismantle very carefully, watching for location of components and avoid letting anything fall or leap out of place, otherwise avoidable detective work is required to reposition contacts etc correctly.) Works pleasantly now.
Checking over the circuit boards I avoided disturbing any presets, just measuring resistances between their ends, and between each end and wiper connection, and finding values plausible. Nothing in the electronics seemed to require attention.
Cleaned filter (new cotton wool) and water separator and tried instrument, following instructions for use in manual (kindly made available by Michael 5of9 in early post). At first there was much fairly wild excursion of the meter needle, but after some minutes things settled down somewhat. Sufficiently for roughly measuring the CO2 in my breath as a few %. From information available from various posts it seems that the instruments needs to be kept well exercised to behave stably.
Regarding the question originally posed (how does it work for both CO2 and CO, using only one sensor, as in my instrument also) I speculate that the Pegasus combustible gas sensor works for CO detection by oxidising the CO (catalytically) on a heated surface, and measuring the consequent temperature rise. For CO2 detection, which according to the Anagas manual is achieved by measurement of gas thermal conductivity, the same sensor could perhaps be made to work by only gently heating the surface (insufficiently to stimulate oxidation of combustible gas), in which case the temperature achieved would be limited by the ease of heat transfer from the surface to its surroundings. With a suitable flow regime (low flow speeds, small dimensions) this heat transfer coefficient would vary largely according to gas conductivity, which could therefore be deduced from the temperature of the heated surface.
Many thanks to all who have posted useful information, without which I would have got nowhere with my Anagas instrument.
Next challenge is to achieve DIY calibration (without of course buying special gases). CO2 seems fairly easy in principle, but CO more of a puzzle. I have not yet looked on internet for ideas. Time is always in short supply.
 
Maintenance: Grease and Oil Moving Parts

Main rotary switch turned roughly and stiffly. Dismantled (carefully spring out 2 plastic hooks to separate body), cleaned and greased (Vaseline) rusty ball and spring detents, reassembled.

A high temperature silicone grease is essential because the parts will have ware; https://www.rocol.com/products/high-temperature-silicone-grease

The pump mechanism a drop of sewing machine oil would be better than engine oil; Buy Sewing Accessories Singer Sewing Machine SUPER Oil and Haberdashery at low cost

It would be good to see some more photos of this pump
 
Greetings again. I have been occupied with other things recently.
The pump motor armature looks from the commutator end just like millions of other little permanent magnet motors, but at the other end is this delightful centrifugal governor. Thinking about the CO2 sensor indicates the importance of a constant gas flow rate, and this is presumably the reason for the governor.
The eccentric is basic and straightforward. It could have been designed with much lighter components, and would have resulted in a quieter and smoother running piece of equipment.
I use generally clock and watch oil for timepiece repairs, but use engine oil for the slowest parts of clock movements, and always for clock mainsprings. In suggesting sewing machine oil are you thinking of long life without oxidising and thickening? If it does last a lot longer then it would be worth it. But does it? (I know that 3-in-1 type household oil dries or disappears remarkably quickly, and would not use it for this kind of equipment.)
 

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Maintenance: Grease and Oil Moving Parts

pump motor armature looks from the commutator end just like millions of other little permanent magnet motors, but at the other end is this delightful centrifugal governor. The eccentric is basic and straightforward.

Yes I agree; well thought-out. The work you have undertook on the pump motor would be described more than maintenance or service; say rebuilt? In this case; consideration to clean, inspect (include resistance and current checks), adjust and a lasting grease/lubricant is of the uppermost importance, as the likelihood of this work been carried out again is likely to be slim.


In suggesting sewing machine oil are you thinking of long life without oxidising and thickening?

We need a lubrication/oil that will be slow to dry out thus preventing warmup leading to seizure! Consideration of the type and amount as to prevent contamination to other areas must be considered!


If it does last a lot longer then it would be worth it. But does it? (I know that 3-in-1 type household oil dries or disappears remarkably quickly, and would not use it for this kind of equipment.)

If you are undertaking user maintenance (annually); the writer says “Flue-gas pump; mechanism occasionally requires a spot of light machine oil; as directed in section 4. The pump is designed to provide a minimum suction of 125mm/Hg” a drop of oil on the end of the governor/mechanism, I would set this unit so as the drop of oil will have the chance to reach the most inner part of the moving arm.

On this occasion as the pump motor was disassembled a smear of the mentioned high temperature grease (it’s translucent) would be the optimum way to lubricate don’t you think so?

Which is preferred; well what have we on the shelf for starters that would do, I would use either sewing or clock oil.
 
potentiometer (trimmer) notes

Here is my record of the trimmers (8 in all), none of which I have adjusted. All I have done is to measure their resistances between each pair of legs, to assure myself that they are all in order (particularly conducting between the track and wiper).
While doing this I tried to assure myself that the ICs were making good contact in their sockets. If I had felt dubious I would have removed the sockets and soldered the ICs straight into the board, but they look fine at the moment.
 

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