Help needed - Firing up my grandads steam boiler

Hi Guys,

For many years I have been in possession of my granddads model workshop, steam boiler and stationary engine.

This one is designed to work on propane gas. I have talked to my uncle about this and he knows that it was pressure tested, it also had water residue when I blew air through it so I know it had been used at some point. My grandad did several boilers and some were on model steam engines that you could ride. This was probably his smallest boiler.

I have been researching how to run a steam boiler and I know the importance of maintaining the water level around 2/3 full.

There are two things I am unsure of. Firstly the optimal pressure. I could guess around 60 to 70 psi but I am not sure. The gauge goes up to 120 psi.

Secondly - there is a small valve that you can see just in front of the large brass vent on top of the boiler... I have no idea what that does. It seems unusual that it is placed right where the exhaust heat will be coming out. When I first touched that valve I found it was only open a crack.

Thanks,

Matt.

Looking at what the engine is driving I would think a working pressure of no more than 60 lbs will be needed, the valve near the exhaust could be a steam blower to create a draught for the burner gases and will only need to be open a crack you should be able to see a upturned pipe in the exhaust flue if it is a blower.

Mike.

Edited By MichaelR on 17/09/2023 09:16:14

I go along with Mike that the little valve may be a blower to help the fire draw but with propane this would seem unusual. If the boiler had been based on a design that used coal then that would be normal. That the pressure gauge max is 120 psi would give a clue that the working pressure is 80psi or less. Running on propane or butane will require the gas pressure to be just right and the air supply also - this may require a certain amount of adjustment to keep the flame on the burner. Yes the water level should be in the glass and 2/3 would be fine.The driven models look like the ones made by the german company Wilesco. Good Luck. Noel.

Just had another look at the valve near the exhaust it could be a steam feed for the engine or engine exhaust, could do with a picture of that end of boiler for a better look.

Mike.

Edited By MichaelR on 17/09/2023 10:06:56

The 'little valve' may be a safety value - above a certain pressure it lifts and blows off steam to avoid damaging the boiler. They can be tested by lifting them - use a rod because the valve will be hot and it might blow steam over your fingers.

Not much steam pressure will be needed to drive that model workshop. My guess is 10psi or less. The few engines I've built were about that size and I ran them on compressed air. Best made one ran at about 3psi, my rougher engines needed 5 to 8psi.

Volume of steam or air matters more than pressure.

For a first run, I'd disconnect all the belts, raise steam gently to about 5 to 10 psi, and then open the throttle. If it doesn't run at 30psi, something is wrong - stop and ask again.

Looks OK but assume at first that the boiler is a widow maker! It's a pressure vessel full of superheated water. If it fails, perhaps due to internal corrosion, might go bang and fling metal fragments about. More likely to fail by splitting and spraying a brief fountain of steam and boiling water - don't get too close. Safety glasses and a simple shield.

Worst case by far is injuring someone else - the legal and insurance complications are potentially horrible.

Dave

Thanks for all the replies.

I have uploaded a couple of extra photos to shed some light onto it.

My uncle told me that most of my granddads boilers were designed to be run on either coal or propane. This is an exception obviously but I wonder if this has something to do with the mystery valve.

Now as a beginner I found something that did surprise me. All of the simple diagrams I have seen of a small boiler show the flames or heat touching the boiler cylinder itself. However when I opened the small inlet designed to assist lighting the burners I could see four copper tubes that attach to each end of the boiler, there are two above each row of flames from the burners. This will obviously assist heating up quickly but I was wondering how common this is.

Noel that tip about Wilesco was invaluable... I had a look at their catalog and I could see at least one other model that looked vaguely familiar. I believe you are correct. Thanks.

I am a bit concerned that I cant see a safety valve on the boiler. I am also concerned by the talk of "widow makers".

Proposed course of action:

Fill boiler & tank with water. Use the handpump to pressurise the boiler. Bleed any air out through the whistle, then pump up to 100 psi on the gauge. If there is a safety valve, you will know from the water coming out when under pressure. Ideally you would then remove the safety valve, put in a blank plug and pressurise to 120 psi, hold it there for 10 mins and check there are no problems.

You would then be safe to steam it up at pressure up to 60 psi. If there is no safety valve, do not steam it.

Better still, find a friendly club and join it. Let us know where you are and I am sure you will make contact with someone on here.

Martin

When a boiler is first tested by an inspector, it is hydraulicaly tested to 2 X working pressure, so a 120 psi gauge suggests 60 psi as the normal operating pressure.

Subsequent, usually annual, tests pressurise to 1.5 X W P.

The boiler inspector wil also check that the Safety Valve can release stean faster than the boiler can generate it.

Re safety.

A pressure vessel failure can be very injurious. A small boiler may not necessarily be a "widow maker", but it could be!

Even if the metal does not fragment with the danger of shrapnel flying about, the steam contain a LOT of energy.

At 60 psi, the steam temperature will be well above 100 C, probably nearer to something like 170 C.

For every gramme of steam that impinges on you, there will be 70 calories released as the steam cools from 170 to 100 C. But the real damage will the steam condensing to water; each gramme will release 536 calories, as it condenses to water at 100C.

So the quantity of heat released from Steam at 170 C hitting flesh at 37C will be about 670 calories PER gramme

And a gramme is a small unit of weight, so in reality, there would be a much greater weight of steam flying about.

That will be sufficient to strip skin!

So be VERY careful!

First job, in my book, would be a hydraulic test to 1.5 W P, probably 90 psi, (This will require various fittings to be renoved and blanked off ) followed by a steam test to 60 psi, to check the safety valve.

Howard

Gentlemen, I don’t think it’s necessary to scare newbies to the hobby… A dash of respectful caution maybe, but anything more for this little kettle may be unwarranted.

Matt…

From the limited pictures and views it looks like the boiler and other bits and pieces are exceptionally well made, and I would be very surprised if there’s anything wrong with the boiler. It also looks like its silver soldered which is more than adequate for a small gas fired boiler like this. This set is something special, and I would enjoy and cherish it for as long as you can.

The copper tubes are circulation tubes and are common on smaller boilers that are externally fired, especially when built by experienced model engineers.

The blower at the chimney is probably to make the boiler look ‘cool’, with a little condensate (‘steam&rsquo coming from the chimney that would otherwise be clear when gas fired. It will also help pull a draft and keep the flame healthy. The lower the safety valve is set the more you'll see 'steam' in the exhaust plume.

It looks like the safety valve is behind the whistle on the steam dome. I would check that this lifts with a bread knife (just a fraction, if it moves its working). It should have a small groove at the top. If it’s stuck just leave it overnight in a little citric acid-water solution.

Fire it up! Post a video! It all looks fantastic and I would love to see it working…

PS: the sat temperature at 60PSI is around 145DegC according to the steam tables; the energy release quoted in calories is based on some rather bold assumptions of direct heat transfer not taking into account secondary convective heat fluxes and latent heat removal…

Matt, Your latest picture solves the valve question, it's the main steam control valve for the engine, the tube on top of the valve body looks like it could be for engine lubricating oil as it seems to have a screw cap for filling.

The first picture was a optical elusion that made me think the valve was a blower and fastened to the boiler.

Enjoy your model. Mike.

Edited By MichaelR on 17/09/2023 15:27:58

Fully agree with Luker. Given the obvious high build quality it suggests the builder was well aware of what they were doing so I would be surprised if there were no safety valve and suspect it is as Luker suggests.

Range of the gauge is no reliable indicator to working pressure. Gauges are best sized for operating pressure to be between half and two thirds full scale deflection, so that suggests 60 - 90 psi. However looking at the engine I very much doubt it needs 60psi to do its work. Use the hand pump to carefully raise the pressure and see where and at what pressure the water escapes if nothing comes out by the time you reach 100psi do some investigation! Given the size of the boiler, depending on its working pressure it is likely to fall under the “small” boiler code.

As to the scary words, the mode of failure of this size of boiler, should it fail is unlikely to be catastrophic resulting in the projection of shrapnel! Be cautiously careful rather than hysterically scared! A one off or periodic hydraulic test is no absolute guarantee a boiler is “safe” unless combined with a good visual inspection. There have been plenty of boilers successfully hydraulically tested that have later failed in service due to localised pitting or wastage!

Enjoy your grandad’s efforts.

Paul.

I have no wish to scare newbies, rather to help and encourage them.

But stean under pressure is dangerous. Get a scald from a kettle, at ambient pressure, and you will begin to understand.

If you have seen or heard of pressure vessel failures, you will be careful. (One of my colleagues lost the ends of fingers due to a failure! )

I am no H & S addict, far from it, but we all need to be safe.

Not warning someone, so that they are injured does them no favours, and damages the hobby.

By all means steam the engine, but first ensure that it is safe so to do.

The construction looks be excellent, so just make sure that time in storage has not reduced conditions to where there might be a danger.

It's the gung ho types who eventually finish up in A & E, (If they are lucky ) so don't condone or encourage that sort of behaviour..

Howard

Edited By Howard Lewis on 17/09/2023 16:13:50

Firstly I agree whole heartedly with Luke R this is by the look of it a well made model, not a nuclear reactor approaching criticality ! A simple hydraulic test can be done, it has a gauge and hand pump, YES, YES, YES I know the gauge has not been calibrated against a known standard. I fancy the item near the chimney is the safety valve, The feed to the engine comes out of the firebox casing and runs to a standing valve ( or is it a lubricator) which controls the engine - there may even be a small degree of superheat as the pipe passes over the burners. Good practice would be to use a pressure gauge of 1.5X working pressure so 120=80 But an engine like this would run on 30 psi or less.

Fill the boiler brim full and vent any air then slowly using the hand pump raise pressure and check that the gauge works first, if yes take it up slowly again to 60 or 80 psi ! If it hasn't split a seam or water is pouring out then it will be quite happy at 30 or 40 psi you wont need more. What's it's bar litre value ?

If your anywhere near me it would be a pleasure to help get it running, send me a PM. Noel.

Thanks guys,

I can confirm the safety valve is right next to the manual pressure blow off lever at the top middle of the boiler.

I like the idea of purging the air and doing a simple hydraulic test. This will check the basic safety as well as confirm that the pressure relief valve is functional. This will be step no 1.

I also like the idea mentioned earlier that this model may run at very low pressure... less than 10 psi. I have oiled the points and the mechanism runs very freely. I don't think it will require much to simply get it running. If I can get it moving under 10 psi I wont go any higher. I don't plan on making it race.

At this point I just need to wait for a 1/16 BSP tap to arrive so I can connect the gas line safety so it will be a couple of weeks before I get going. I am looking forward to running a boiler for the first time.

Matt, have fun, I am sure it will run well, it looks a cracking set up. Beware though I am sure there will now be a raft of dire warnings on gas safety……

Paul.

1/16" BSP ? Noel.

Lagging the steam pipes is a must.

Bob

This forum would be quite good if it wasn't for the Worshipful Company of H&S Inspectors and Chronic Over Thinkers.

Martin

Having seen the after effects of pressure vessel failures, you can't be too careful.

I have little time for H S E over reactions, but with a device that is unknown, it is foolish to take risks, without checking, before subjecting it to full steam pressure..

Who would climb a mountain without being certain that the ropes were in good condition and sufficiently strong?

A working colleague lost the ends from his fingers when a pressure vessel failed.

Steam under pressure has the potential to do even more damage than a simple scald (Which is pretty painful )

It contains a LOT od heat energy.

Work out the risk if a small boiler fails.l

A 2" diameter boiler end, under 60 psi is subjected to a force of just over 180 lbs.

Any volunteers to be on the receiving end of that if it comes flying?

Plus the heat energy in any steam that hits you?

Just be careful!

Maybe that procedure is only for professional Engineers with a wish to live long and free from injury?

Howard

Howard,

There were some eminently sensible suggestions made in this thread on how to approach this in a safe manner including the use of the hand pump to carry out a hydraulic test. This is hardly an unknown device, OP made it clear the builder, his grandfather, had built other boilers in the past and it’s fairly obvious just from a cursory visual inspection of the pictures that the standard of workmanship is excellent.

”work out the risk if a small boiler fails” that is hardly a relevant statement, you have done your best to highlight what happens if it fails, you note the possible extreme consequences in some detail. However, the risk you should be considering is what is the probability of failure! As I am sure you know to do a formal risk assessment you identify the hazards, you then determine a likelihood of occurrence and then apply that to the severity of the consequence. If the risk is high then you apply mitigations. Doing that on the fly (a dynamic risk assessment) and applying the mitigation of a simple hydraulic test gives me a very low risk.

I am very sorry to hear of the fate of your colleague but clearly the risk assessment for whatever he was doing failed, either there was no procedure from a formal assessment, it wasn’t followed, was inadequate or in its absence there was no dynamic assessment made. You give no details of the incident to link its relevance to this situation beyond it was a pressure vessel that failed. Unless it is directly relevant then it’s not suitable for discussion here.

Boiler safety in general is not solely governed by a successful hydraulic test and visual inspection on an annual basis it also depends on the operator of the boiler and how he manages it between inspections - rate of firing / steam production, feed water quality, quality of daily and periodic inspections etc.

What is being discussed here is little bigger than a Mamod which apart from an initial inspection at manufacture has no other inspection regime and is in fact designed to be operated by children. A compressor from a DIY outlet that is a few years old and hasn’t been looked after is a far higher risk than a boiler probably less than 2 bar litres (to be determined) and the risk associated is reflected in the minimal requirements of the MELG small boiler code.

You have highlighted the potential consequences so you should consider your duty done, there is no need to continually try to justify it.

Paul.