Copper extinguisher as boiler

[Tony RoulstonParticipant @tonyroulston14754]

Has anyone tried this

[Tony RoulstonParticipant @tonyroulston14754]

I am planning to make a vertical boiler to service several model engines. I was searching my local merchant for some material when I found a copper fire extinguisher, which is marked as tested to 350 psi. I can see how this could be a viable basis of the boiler. It is a beautiful riveted and soldered shell and of the right size. Does anyone have any advice or comment on the concept?

[David Clark 13Participant @davidclark13]

If it is soft soldered the temperature may melt it. It does not matter what pressure it is designed for, you will have to test it at the pressure you need plus the safety factor.

[Gordon WParticipant @gordonw]

Fire extinguishers can make very good boilers, 2 things tho'- pressure test full of water, – You can't use it in public, needs boiler inspection for insurance.

[Ady1Participant @ady1]

Does anyone have any advice or comment on the concept?

Fire extinguishers are designed to be used at room temperature

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by David Clark 1 on 02/10/2015 09:13:09:

If it is soft soldered the temperature may melt it.

Yes, although that does depend on the intended operating pressure and thus the operating temperature. As it's riveted the soldering is probably for sealing rather than strength in any case.

What is the volume? If it is less than 2 litres (if I remember correctly) or operating at less than 0.5 bar there are no specific legal requirements other than your duty of care.

Russell.

[Tony RoulstonParticipant @tonyroulston14754]

Thank you all. I would of course undertake a hydrostatic test prior to firing. Also as It will need to be opened up for fitting tubes etc I will be able to test the soldering and silver solder the seams or at least hard solder it if required.

I have no plans for public use, and the legal position in AU likely mirrors the UK. Think it will be about two litres in water volume once the fire box and tubes are fitted. I have K.N. Harris;s book on model boilers and was going to follow a proven approach otherwise but when I saw this beauty I am sure it can serve as a good base and have some historic athletics as well.

I am only looking at a max working pressure of 60 psi to run bench models and I have contacts is the SCUBA industry that can test it well beyond anything it would see under stream, they test my dive cylinders to 500bar.

Thanks all.

[JasonBModerator @jasonb]

You may well have difficulty silver soldering an item that has already been soft soldered as the old soft solder is likely to have been lead based and that will contaminate the work.

A vertical boiler will have the firebox at its base so that is likely to be the hottest part so the pressure/temp won't come into it but on the other hand you will not need the caulking to retain steam in the firebox section

[Tony RoulstonParticipant @tonyroulston14754]

Posted by JasonB on 02/10/2015 11:41:48:

You may well have difficulty silver soldering an item that has already been soft soldered as the old soft solder is likely to have been lead based and that will contaminate the work.

A vertical boiler will have the firebox at its base so that is likely to be the hottest part so the pressure/temp won't come into it but on the other hand you will not need the caulking to retain steam in the firebox section

This has occurred to me, thank you. I do plan on having a seperate steel firebox that the boiler would sit on.

I was inspired by Keith Appleton's nice big vertical boiler and RCDON's https://www.youtube.com/watch?v=8FXeYKvQQ6o. In the end this is just a heavy walled copper shell to give me a head start. Regards, Tony

[JasonBModerator @jasonb]

Thats a nice boiler, he uses rivits and the expanded ends of the tubes for structural strength and soft solder to just seal or caulk all the joints. Generally this method is not used as much in the UK now instead all joints use a stronger "silver solder" with a much higher silver content

The boiler mentioned above

[Author]

Posts