# LPG/propane/butane Gas jet sizes



## doubletop

Tonight I've been researching a new burner for my Rob Roy based on an article "Gas Firing for William" C H Hopkins (Oz) in Model Engineer 18 July 1986 and "Propane Burner" Lindsay McDonnell Modeltec Magazine June 1989. These articles were the basis of successful burners being used on model locos in NZ for some time.

The idea is to get more gas an air into the system and better combustion. I've just spent a number of hours trying to find out what drill sizes relate to gas jet sizes numbers so I can quantify the #15 jet in my ceramic burner. A bigger number is larger hole but a bigger drill number is a smaller hole, so its not that. I've found a web page that gives the BTU/hr for various hole sizes vs PSI.

http://www.joppaglass.com/burner/lowp_chrt.html

http://www.joppaglass.com/burner/highp_chart.html

Anybody got any clues please?

While we are on the subject, if you are into this you may find this useful

www.eclipsenet.com/catalog/contents/Documents/EngGd/efe825tn.pdf

Pete


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## John Rudd

I found this with hole sizes..





Gas Jets, sizes 5 Ref: FTGJ5 

Jet No 5 : 55grm/hr (for butane/propane burners) consumption rate w/valve fully open (figures for guidance only as consumption can vary under different conditions); thread size 1BA, hole size .2 mm; 







Gas Jet, sizes 8 Ref: FTGJ8 

No. 8 gas jet for butane/propane burners; 69grm/hr (for butane/propane burners) consumption rate w/valve fully open (figures for guidance only as consumption can vary under different conditions);
Gas jet thread 1BA, hole size .25 mm 







Just need the right size of bit to make the hole..


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## shred

Here's one reference for model gas jet sizes: http://www.homemodelenginemachinist.com/index.php?topic=2049.msg39589#msg39589



			
				SandyC  said:
			
		

> Hi Shred,
> 
> It looks like you are having a great deal of fun with that loco and what a great job you are making of it.
> 
> You mentioned that your gas jet had a weird 'metric' sort of thread..... well, the majority of the small gas jets used by manufacturers of camping gas cookers, DIY blowlamps and model steam loco's ('G' gauge etc) have a 1BA thread..... which is based on a metric form..... 5.3mm OD x 0.899mm pitch (0.2087" dia x 0.0354" pitch (28.25 TPI))
> 
> 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.
> It is, therefore, possible that JetBoil get their gas jets from 'Coleman', with their own 'CUSTOM' markings on them...... if so then they would most likely be 1BA thread.
> 
> 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: -
> 
> Number 3 which has a 0.15mm dia jet bore
> 
> Number 5 which has a 0.2mm dia jet bore
> 
> Number 8 which has a 0.25mm dia jet bore
> 
> Number 12 which has a 0.3mm dia jet bore
> 
> Number 16 which has a 0.35mm dia jet bore
> 
> All 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..... :big: :big: :big:
> 
> I hope this is of some help to you. ;D ;D



There's not really a drill size correlation as most drill sets don't go that small.

There's also a thread or two on making gas jets, but the search engine here is getting lazy... it took me a while just to find that first link and I knew where it was.


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## doubletop

John/Shred

Just what I was looking for thanks

The Eclipse doc gave me the drill dia for the number codes and the highp_chart from joppaglas the BTU/hr figures for the same drill sizes. With the Calor jet sizes I can relate all the data and get BTU/hr figures for for the calor jets and then establish the relationship between my ceramic burner (with a #15 jet) and the burners in the two articles with jets made with #60 drill and #66 drill.

I also have the recent article in Model Engineer about the Guilford MES efficiency trials which had 3 Rob Roys competing and provides details of the calorific value and the amount of coal used so I should get some idea of the amount of heat I should need.

I should then be able to establish if my burner can put out enough heat to keep it running before I head off and make a new burner. Well that's the idea (it could be complete tosh but I've got a lot of data)

BTW you may find these interesting (the second link has some good docs)

http://207.200.58.35/Resource%20Library/Forms/AllItems.aspx

http://207.200.58.35/Resource%20Library/Forms/AllItems.aspx?RootFolder=http%3a%2f%2f207.200.58.35%2fResource%20Library%2fGas%20Check%2fCETP%206.0%202001%20Gas%20Check%20Cross%20References&FolderCTID=0x01200016E31ECAED4C8E4AAEB16325DB5F5979


Pete


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