Test Boiler - electric

I am thinking of making a small boiler to test steam injectors and looking for a simple boiler which would have an electric heating element, preferably 240volt.

Working pressure - 90 psi

Volume 1 - 2 litre.

Can anyone point me in the direction of existing plans please, or purchase of same ?

Bob

Edited By Speedy Builder5 on 13/08/2023 09:54:59

Bob,

Check "Blondie Hacks" on Youtube, She has made a small one.

Denis

The first question would be will it be certified ? A modern electric kettle element would work? 150 Dia X6mm wall tube with suitable fittings and welded and stayed one end, flange and bolted the other. A rough idea. Noel

I once knew a chat who used a pressure cooker, also I saw this guy https://youtu.be/mMoQl3-zV0g

H

I have run my Stuart No 1 on a prestige hi dome !

I have an electric steam generator in my kitchen that will produce steam at 8 - 15 bar (115-215 psi). My coffee machine with a thermoblock heater which channels water through a narrow pipe within a metal block that is heated and in turn heats the water.

This would be a boiler for home testing of injector(s) and drained down when in storage.

I am thinking along the lines of using a disposable 2.2 litre CO2 bottle. Its certified test pressure is 163 Bar and Working pressure 100 Bar.

Silver soldered steel tapped bosses for all outlets.

200watt 240 v tubilar heating element £6:00 (Alliexpress or similar).

Working pressure of 100psi and test pressure of 200psi (14Bar) - this is well below the original design pressures albeit with modification of added bosses and elevated temperature.

These are my ideas, Am I dreaming ??

Bob

As Paul suggests, Flash steam.

Speedy builder, I am going the same route but with 500watts and using a lot of ideas from DAG Browns injector book. It really needs a method of switching when up to WP to make the thing useful so injector tests can be done without having to keep an eye on that part of the job.

A couple of the posters on Model Engineering Clearing House have designed, built, and used electric boilers for injector testing. Roger and terrier060 come to mind so maybe worth searching their threads, tho' others have also done-so.

Phil

Looked at using a pressure switch similar to those on air compressors. We use similar over here on water pumps but I am wondering if they will be too slow to react and the lag between on and off and consequent delay in heating/pressure drop. I did wonder if temperature measurement would be a better way to go however that would have its own problems.

There are 12 volt 120watt car kettles, but they are slow in getting up to temperature. Domestic kettles are 2000 watts. Perhaps 500watt would be better .

thanks Phil, great link ME Clearinghouse.  You need to go through the "I am a robot" bit then submit the pre-filled search

Test Boiler

Edited By Speedy Builder5 on 14/08/2023 08:28:49

Roger Froud's electric test boiler is shown running on this page of MECH. Scroll down to Dec. 18th posting (Dunno if you have found it yet). He details construction and controls over a variety of preceding pages.

Terrier060 does similarly in his electric boiler design and construction.

If you cannot find the information that you require then maybe post your enquiry there too (under 'General Chat'  ) and you will get assistance.

Phil

Edited By Weary on 14/08/2023 08:58:02

Terrier 060 refers to his heating element being 2800W and designed for a coffee machine with working pressure 100 psi. If anyone finds a part# and supplier (preferably UK) can they post it here.

That is a hell of a coffee machine. Flash steam ?

Duncan, try this one ??

Miniature water heating element

I suspect it's the sort of thing you find in a big coffee house, not your kitchen. Some googling brings up Fracino, in even higher wattages, but no mention of working pressure.

Edited By duncan webster on 14/08/2023 14:51:33

Thanks, but I've had bad experience of directly importing electrical kit from China. Never again. One instance was simply not safe, the second had a moulded on 3 pin plug with no fuse. Definitely doesn't meet BS. OK it wasn't difficult to cut it off and fit a proper plug, but it only worked for a couple of weeks after that, so it went in the bin.

One interesting point is the spec ! It shows 1/2"dia then says 21mm - this should read 1/2"BSP ! pipe dia is 21mm. At the price it might be worth giving it a go ? Noel

Responding to Noel -

It does not need certifying if you are going to be its only user at home; though certainly do still test it.

If you intended offering its use to, say, other members of a model-engineering club then you would need it formally passing fit for service by the club boiler-admirer just as if it is part of a miniature locomotive or traction-engine. Though I suspect some club boiler-testers would refuse it as too unfamiliar or the like, to them; or on grounds of it being a steel boiler of unknown provenance.

You won't go far wrong by adapting the standard MELG handbook instructions for its cold hydraulic test as a new boiler, and for testing the safety-valves as per the "Steam Accumulation Test". The instructions cover only testing a pressure-vessel: they do not cover how the water is heated, as that is not relevant.

.

SpeedyBuilder:

At least you've the advantage with electric "firing", that if summat happens as shouldn't, you simply switch it off!

Whether manually or by a pressure-switch does not really matter. There is little metal in this proposed design to hold heat, and once the element is off, the boiling will diminish and stop very rapidly.

'

[As an aside, if you ever had the pleasure of seeing Ron Jarvis' working model Newcomen Engine, you might know its boiler, about the size of a small orange, is electrically heated, with the controls on a discreet panel in the plinth. Both the original and scaled replica worked at a heady 2 psi, and Ron realised electric "firing" and fine control was the only way forwards, so designed and fitted the appropriate equipment. As he wryly commented, there can't be many 18C atmospheric engines with automatic microprocessor control.... ]