Gas jets

[Eddie Price 1Participant @eddieprice1]

Hi, I am in the process of making a  steam plant for a model boat, and I am at the boiler stage. I have been using Martin Ranson’s articles in Model Boats as a guide. He mentions gas jets Nos 3 or 5 for his burners. Does anyone know of a supplier of gas jets?

By the way does anyone have any experience of machining phosphor bronze. I have used it for the first time to make bushes for the boiler and it appears to be terrible stuff to machine. It is the first time that I have broken a tap (okay, perhaps I have been lucky in the past), but both drills and taps appear to bind in ph bronze. Are ther different grades of ph bronze?

Eddie Price 

[Paul TParticipant @pault84577]

Hi Eddie

For gas jets try a camping / caravan or outdoor store.

For machining ph bronze I suggest that you talk to an expert machinist such as our very own Bob Abell.

Paul

[Eddie Price 1Participant @eddieprice1]

Thanks Paul. How do I contact Bob.

Eddie 

[HS93Participant @hs9317166]

Hers are three people who sell them

http://www.pollymodelengineering.co.uk/sections/bruce-engineering/fittings.asp

http://www.forest-classics.co.uk/ceramic_burners.htm

 http://stores.ebay.co.uk/Clevedon-Steam

Hs93

[Paul TParticipant @pault84577]

Eddie

Bob is one of our more prolific members, to find him just scroll down the forum postings and you will find his name and from there you could contact him through the "message member" facility.

Alternativly just wait for Bob to log onto this thread and leave a note of his own.

All the best

Paul

[Eddie Price 1Participant @eddieprice1]

Hi folks. I am not having any success with my gas burner. I have managed to get Nos 5 and 8 gas jets, but I am not having any luck with the completed burner. I have been using the information provided by Martin Ranson, Model Boats, June 2005, August 2007 and July 2008. I have constructed a burner similar to Martin’s with metal gauze at the outlet, but cannot achieve the nice blue flame that Martin shows in the August 2007 article; I always end up with a yellow fringe. I would be pleased to hear from anyone who has successfully constructed gas burners. Not the ceramic ones, which I have managed to make. I want one that will project a flame horizontally in a boiler similar to that which appears in the June 2005 issue of Model Boats.

 Eddie Price

[Paul TParticipant @pault84577]

Hi Eddie

From your description it sounds as though you have a air / gas mixture problem which is resulting in this incomplete burn. 

Lots of questions arise from the mixture problem such as Gas Type & Pressure, Regulator Size, Pipework Size, Size & Type of Gauze, Size & Location of Air Inlets, Size of Combustion Chamber (if any) 

Or perhaps the jet is partly blocked.

Are you working indoors or outside as drafts can cause havoc with small burners.

Don’t despair as we all go through the same learning curve when playing with gas.

Paul

[Eddie Price 1Participant @eddieprice1]

Thanks Paul. I am still struggling with it. I have added some pictures to my gallery, including the burner. This is what it looks like

The jet is on the left, the mixing chamber is in the centre and the gauze holder bottom right. The large flange is intended to fit over the opening to the boiler. I have tried different jets, Nos 5 and 8, and 8 just gives me a bigger flame

It is such a simple structure it is difficult to see what I can change. I have examined gas torches that I use in the workshop, and it is difficult to see why they work and the one above doesn’t. Oh well keep trying, and if there is anyone out there who has made something similar, that works, I would like to hear from you.

Eddie Price

[Paul TParticipant @pault84577]

Hi Eddie

Just had a good look at your burner set up and two questions occur to me,

Firstly have you tried sliding the jet and its mount forward / backward in mixing chamber as this will affect the way the flame burns (sorry if I,m telling you how to suck eggs)

Secondly the distance from the jet to the opposite wall of the combustion chamber is critical as this will also have a distinct effect on the quality of the burn, it might pay to check the design distance.

Good luck

Paul

[Eddie Price 1Participant @eddieprice1]

Hi Paul. Yes I have tried moving the jet and when it starts to cover the air holes the flame goes more yellow, but even with the air holes completely uncovered the flame still has yellow edges.

With regard the distance, I think you are correct in asuming that there are some critical distances involved in the design, but the design information is not that clear, so I suspect it is going to be a process of trial and error. The old bunsen burner is very simple (I don’t suppose schools are allowed to use them now), but making one is not so easy. 

Eddie 

[Paul TParticipant @pault84577]

Hi Eddie

Doe’s the combustion chamber have to be right angled to suit your boiler or could it be straight?

Paul

[Eddie Price 1Participant @eddieprice1]

Yes Paul I would prefer it to be at right angles, as per Martin Ranson’s design, and recent adverts in MB of the Stuart Puffin marine plant has a burner at right angles. So I presume they work. I will keep trying

Eddie 

[Eddie Price 1Participant @eddieprice1]

I am having second thoughts about the right angled arrangement. Very difficult to get a good flame and when I do, and I direct the flame into the fire tube it goes out.

I have been experimenting with a pencil jet. I have one of the small gas torches that are advertised for budding chefs to make their creme brule!. The torch normally produces a roarer type hot flame, but by adjusting the air flow it will produce a very nice quiet blue pencil flame. This is my experimental lash-up.

A bit of yellow at the end of the flame, but not a serious problem. I am using a No.3 gas jet. This is the end view of the burner

The outer tube is 10 mm in diameter, the inner hole is 2 mm diam and there is a rind of 1 mm holes, which are linked back to the central hole via a grove machined into the body of the tube. I just need to put the jet and burner together, and I should have a nice burner.

Eddie Price

[Eddie Price 1Participant @eddieprice1]

This is the final version of the pencil jet burner:

It produces a nice flame. There is a tinge of yellow, but I don’t think it will be a serious problem. These are the component parts:

The design is partly based on the appearance of the small commercial gas torches and the information found here http://www.abymc.com/Articles/Submitted/PropaneBurner.html. The No 5 jet in its holder is on the right; this slides into another holder which allows the jet to be positioned back and forth to optimise the flame; next is the burner tube with a length approx 8x its diameter according to the info in the above reference, there is a venturie in the end where the jet is positioned formed with a 90 deg countersink; finally there is a flare tube, which ‘holds’ the gas as it emerges from the array of holes and produces the pencil flame.

This is another view of the jet holder and the end of the burner tube:

Just need to put all the parts together now. Will keep you posted

Eddie Price

[Fred Graham 1Participant @fredgraham1]

Hi Eddie,

You probably feel like you’ve worked a miracle. It’s a great feeling when it comes together and Martin Ranson has produced some great articles, but in the end, trial and error is a great teacher. Keep notes as you will/may forget what improved things and what did not.

You may find the next issue to deal with is the ‘cooling can’ problem. When you burn LPG, as it is drawn off the can, depending on how fast you use it, the can will cool and boiler performance will drop.

Martin has written some good articles on avoiding this problem using heat shunts to keep the fuel tank warm. I, myself, have successfully used a vaporising coil wrapped roung the entrance to the centre flue so that the heated zone warms the gas enough to vaporise it. It then burns as normal

You need a tank with two valves, one which feeds gas until the flue is heated and one which feeds liquid fuel taking it from the bottom of the tank. This is an idea of Peter Arnott, and not my originality I hasten to add.

When I first started my own experiments I had litle to go on, but perseverence got me there in the end.

Anyway well done with your own trials, not many folk try doing this kind of thing these days, or if they do they seldom burst into print with their experiences.

All the best, Fred Graham

[Eddie Price 1Participant @eddieprice1]

Thanks Fred

You bet. I am afraid I did not manage with Martin’s design. I was obviously doing something wrong, because Martin has some superb designs, which obviously work. 

I have been wondering about the gas container. I am not really up with the rules for steam, but I note that most setups, Martin’s included use custom-made tanks, rather than the commercial gas cylinder. Obviously for attaching a heat shunt then the custom-made tank is necessary, but are standard gas cylinders permitted?

I did see a design for a pressure regulator for a standard gas cylinder, which I have made. It seems to work, but I don’t have a pressure gauge so have no way of knowing whether the pressure holds steady, but of course it does not cope with the loss of pressure which results from the gas cooling, and losing pressure as it is released. It is okay if the cylinder is over pressurised as a result of being in the sun.

Eddie Price 

[Fred Graham 1Participant @fredgraham1]

Hi Eddie,

You will probably find that most suppliers have tanks which have one valve for feeding the burner and a filler valve which is very similar if not identical to lighter filler valves. Although many people use these successfully I am not very impressed with them. I find it very difficult to ensure that I have filled the tank and fuel seems to spurt from the filler nozzle before the tank is full.

Many people do use standard gas cylinders and a special connector is available to screw on to the top of these cans. The connector has a valve for control of the gas to the burner. Suppliers such as Forest_Classics and Maccsteam will supply these and they are on the internet

Martin Ranson has written an article which describes his method of filling which is much more reliable but he makes his own tanks. He advocates three valves on his tanks, one for filling and on for venting when filling. A third valve is used for the burner supply but this means making your own valves. I have made my own based on Martins designs and they work fine. My own tank has a supply valve which allows neat fuel to be fed to the burner by having a tube reach to the bottom of the tank. This is based on Peter Arnott’s design and also works well but requires a vaporising coil to ensure acceptable burning.

Martin also believes that a pressure gauge is desirable in the supply pipe as this can be very useful to see what is happening when the burner is working.

Martin has written an article in a recent Model Boats mag. (July 2008) so you can see his designs for your own interest. My own boiler is shown in this forum (Steam) under LPG burners where a picture of the boiler with a vaporising coil is featured.

If you are interested in using this method I can advise you further but Martin Ranson has detailed his method of the heat shunt in his article which may suit you better. You mentioned ‘cans in the sun’ and ‘over pressure’ resulting from this. The suppliers suggest that cans are kept out of very sunny places such as in cars. Tanks which are made up by amateurs should also have the filler pipe made such that a space is left into which the fluid can expand and Martins tanks embody this safety arrangement. You would be well advised to use his design to avoid excessive pressure. You may not know but the fluid expands to 250 times its liquid volume when it turns into gas!

You must realise that experimentation with LPG has its own dangers so you must work with scrupulous accuracy when making the tanks and all the fittings and tank testing should be done to regulation pressure. Since making my first tank  I have had another tank made by a professional supplier called Maccsteam and you can find him on the internet. His tanks come with a test certificate and are made to stringent standards. I have no personal connection other than as a satisfied customer.

I hope I have covered the points you asked about and I must assure you that I am no expert in these matters. What I will tell you is what I have actually done myself and any experience I have had with it together with any sources of useful guidance I have found in the modelling press. I believe it is important that you make your own assessment of each new thing you do and be careful as you do it.

All the best, Fred Graham

se

[Eddie Price 1Participant @eddieprice1]

Hello Fred

Thanks for the tips Fred.

I think I will make myself a gas tank following Martin’s design. I had a look at your boiler. That is quite something. I see you have managed to get the right-angled burner to work. I will probably stick with my pencil burner as I will have quite a lot of room in the Clyde Puffer that I intend to put it in. The use of a heat shunt does seem a bit hit-and-miss. Martin seems to suggest that on a cold day you attach it, while on a hot day you disconnect it, based on the reading of the pressure gauge. I must admit I would prefer something more controllable. Perhaps the pressure regulator would provide this control. I need to go back to the original article and see what the author (can’t remember the name) has to say. Has Peter Arnott published his vaporising burner info?

Eddie Price

[Paul TParticipant @pault84577]

Hello Eddie and Fred

It is so nice to read a meaningful exchange of views especially by two such connoisseurs of steam.

Eddie I do like your pencil burner and I bet that you will get a better burn performance from it, like Fred says you must take great care if you are going to build your own gas tank when I used to build them I treated them just like a boiler and tested them to the same rigorous standards.

Looking forward to reading your postings on the firing and steaming.

All the best to both of you.

Paul

[Fred Graham 1Participant @fredgraham1]

Hi Eddie,

Peter Arnott has published a series of articles on the subject of burners and vaporising. The article was part of a long set of articles which were about the building of a Vee four oscillating engine.

As it happens I have the full series but they may still be available as back numbers from Model Boats or failing that you can get them from one of the back number specialists, I can’t remember the name at the moment but I got a Model Engineer mag. recently from them so I’ll find the name and pass it on to you.

The articles ran from February to December in 1993 and the specific articles relating to burners and tanks are parts 8 and 9 (ie September and November)

If you have trouble in getting hold of them I can send you copies of the relevant ones if you let me know your address.

Let me know how you get on, I know these developments can be frustrating and take a long time to get done so I find that any help that speeds things up is always useful.

I have just spent the last week or so making a test rig for hydraulic testing of LPG tanks which demand pressure tests over 300 psi and it can be a long job making all the plumbing bits and pieces.

Anyway, keep up the good work and all the best, Fred Graham

[Fred Graham 1Participant @fredgraham1]

Hi Eddie,

The company who will probably be able to supply any back numbers of Model Engineer or Model Boats (ie the one I could not remember in my last note to you) is TEE Publishing, if you are unable to get them from the original supplier.

All the best, Fred Graham

[Eddie Price 1Participant @eddieprice1]

Thanks Fred

I have just looked them up with Google ( I suppose I should say ‘I Googled them’. I can’t get used to this idea of creating new verbs ) It looks quite an interesting organisation, with a lot of model engineering books and stuff.

 I will try them for Peter Arnott’s articles

Eddie 

[Fred Graham 1Participant @fredgraham1]

Hi Eddie,

Don’t forget, if you are stuck, I have copies and if you let me know you’re address I will send you them.

Incidentally you may wish to have look at my just finished LPG test rig and the LPG tank with three valves as I described based on Ranson & Arnott(See Pics)

All the best, Fred Graham

[Eddie Price 1Participant @eddieprice1]

Yes that looks nice. Where did you get your gauge from. I have been looking for one without much success.  I don’t know about gas tank pressures, but I do need one for testing my boiler. I suppose a max of 150 lbs. would be suitable.

 I have found that paper on the pressure regulator now.’Gas Valve and Regulator’ by Malcolm Beak, but I don’t know where he published it. At the time I contacted him directly and he sent me a copy of the original. It is dated 1997. He uses a standard commercial screw top gas canister, and his valve and regulator fits onto the canister. The regulator uses a rubber diaphragm which bears down onto the end of a valve from a car inner tube. The car valve is on one side of the diaphragm and a screw adjusted sprung metal bush on the other side. The gas enters the regulator through the car valve, and the spring by pressing down on the valve controls the amount of gas leaving the canister. It seems to work.

Eddie P 

[Fred Graham 1Participant @fredgraham1]

Hi Eddie,

I bought my gauge from a company in Birmingham who also do calibration testing so that you can maintain the gauge in specification.

Internet address is  ;     www.miniature pressuregauge.com

                                         Email  ;   info@miniaturepressuregauge .com

                                            52-54 Hylton Street, Birmingham B18 6HN England

                                       Tel.      0121-551 9910

My contact at this outfit is Mr J Scott who recently recalibrated my 600 psi and my 400 psi gauges and they also provide a calibration certificate. I use one rig for hydraulic testing of LPG tanks and the other for boiler testing to twice working pressure. There are actually testing regulations with which to conform and most clubs can supply you with the key criteria so that you know what is needed

The pressure regulator to which you are referring in your note is similar to one made by a guy called Roy Darlington who is an expert on ‘Hot Air engines’ and who is sometimes featured in Model Engineer Mags. He attends many of the exhibitions despite his advanced age (over 80 years) and at one exhibition he gave me a sketch of his regulator. I use a CAD system at home called TURBOCAD so I drew it up and sent him a copy. If you want a copy let me know.

 All the best, Fred Graham

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