firing up woes

[runner42]

I had problems in firing up my 5" gauge Black 5 locomotive. I utilised the electric blower that I have previously used on a smaller locomotive expecting similar results, but the heat from the smokebox was too great for the 6 volt motor and it caused it to fail. On reflection I think that the motor was too close to the smokebox and a longer input tube to the fan is required to provide some thermal isolation. The locomotive has unburnt charcoal and wood inside the fire door, which is easy to put in but not so easy to remove. So, undaunted plan B came into action which is to utilise the air compressor and making a small bore U tube stuck  down the chimney and produce an updraft to pull the fire. The compressor has a small leak that cannot be detected but is sufficient to cause the compressor to run almost continously. So I looked at all the possible leak paths and tighten up all the places that could be a problem. Everything was going fine, the leak had been improved. But then a catastrophic blowout occurred. The tank was at 100 PSI and I attempted to tighten the output from the pump at the place where it enters the check valve, sitting on the tank- BANG. I dont know if it was the force of air or the surprised jump that it generated, but I was thrown back off the low canvas stool that I was sitting on and landed on my backside. The check valve is made from some low strength metal that doesn't take much for it to fail, particularly when produced as a thin wall casting or injection mold. The failure point was at the junction of the input to the tank. First thoughts were that the air compressor is a write off, but looking on e-bay I found that check valves are available at a nominal cost and are touted to be a better replacement. However, before getting too exicited I had to remove the threaded part that was still in the tank. I tried a number of ways to unscrew this but it wasn't going to budge. I thought that I would take advantage of its low strength and using a screw driver blade hit it a few times to smash it out of the tank thread. It worked, so a replacement check vale is on order.

Brian 

compressor tank by Brian Leach, on Flickr


compressor input debris by Brian Leach, on Flickr


url=https://flic.kr/p/2phyBvn][/url]check valve by Brian Leach, on Flickr

[uuu]

Your story contains an interesting point. If a small air leak is sufficient to require the compressor to run almost continuously - how much more effort is required to sustain the jet of air up your chimney?

An IWMES member used this firing method - it was very successful at the loco end - but the club's (quite decent sized) compressor was given a good thrashing.

Wilf

[chris vine]

Hi Brian,

Commiserations!

I had a compressor which did this - running all the time but never getting up to pressure.
It turned out that there were two things wrong:

1, one of the reed valves in the cylinder head had lost a corner so it was leaking. New reed made with a bit of shim stock. This partly cured the problem.

2, the piston or cylinder was worn so it was just less effective than it used to be. I had to slightly lower the pressure on the pressure switch to allow it to "get there"...

Hope that helps,
Chris.

[runner42]

Nov 24, 2023 8:53:09 GMT uuu said:

Your story contains an interesting point. If a small air leak is sufficient to require the compressor to run almost continuously - how much more effort is required to sustain the jet of air up your chimney?

An IWMES member used this firing method - it was very successful at the loco end - but the club's (quite decent sized) compressor was given a good thrashing.

Wilf

Wilf, this was only plan B as I am producing a electric blower with a larger 12V motor and having a longer tube to isolate it from the hot gasses. I suspect that the non return valve in the compressor was leaking allowing the pressure to exhaust back to the cylinder. If I am right the replacement should fix this.

What sh*t metal is used in these compressors, it certainly not fit for purpose if maintenance actions are required? 

Brian 

[SteveW]

Years back and more recently and reported here are my compressor woes.

The featured part above was/is the recurring problem. On reaching set pressure and cutting out there is a loud hissing from the pressure switch and the pressure drops dramatically. If the pressure drops enough the motor restarts, stalls against the remaining tank pressure and trips out. The trip is well hidden and tricky to reset once you know its there.

Turns out that although the hiss/pressure loss comes from the pressure switch dump valve the issue is the failure of the big rubber bung not seating in the part shown above. DO NOT ATTEMPT TO DISASSEMBLE THE PRESSURE SWITCH. Its not the problem and a nightmare to reassemble.

Having checked the replacement cost for the rubber valve with the folk at Machine Mart UK I find the packing and postage far exceeds the price of the item so I will continue to revive the valve face on my linisher's sanding disk. I keep meaning to make a little jig with a hole necessary to hold the rubber bung square to the sanding disk. Just need bit of hard wood with the right hole bored in it. Then it'll be just a question of not chucking it away at the next tidy up.

Years back I made a steam raising fan with a small 12 volt motor and an Electrolux vacuum cleaner fan, a couple of bits of 2mm alloy plate, four longish bolts with spacers to hold the plates apart and an adaptor to fit the chimney and centred on the fan centre. It worked very well, in fact I routinely took flack from the club pundit for it sucking too hard. Ended up running it at 6volts. All good.

[runner42]

Received the new check valve all brass construction, so my expectation was to fit the new one, no more than a 10 minute job. WRONG. the 20 mm thread that screws the check valve into the main pressure cylinder was extremely tight, something I often experience with brass thread forms. Because of the shape of the check valve no obvious tooling such as a spanner was possible to use to overcome the tightness, added to the fact that the space was limited by the piping and gauges associated with the pressure limiting switch and compressor outputs. After a struggle using various means to  screw the check valve a quarter of a turn at a time I managed to engage 4 threads, which I considered enough to form a pressure tight seal. The 16mm thread taking the outpit from the pump to the pressure cylinder was no problem. However, the 10 mm thread was another matter. This thread has a convex shaped entry which I assume is the standard for this type of fitting, whereas the existing pipwork from the check valve to the pressure switch is so shaped to allow the 1/4" dia pipe to enter into the 10mm thread and limited by an annulus ring against which the 10mm nut buts up to to form a pressure tight connection. The consequence of this mismatch in terminations I was unable to engage the nut into the check valve. I tried some insitu modification but it didn't work. The consequence was to have to remove the check valve from the cylinder and also the pipe from the check valve and pressure switch. This necessitated removal of gauges to access the nut holding the pipe to the pressure switch. With the new check valve in hand I was able to alter the 10mm thread to form a concave for use of a nut and tail type interface. This required making a new 10mm brass nut and use a 3/8" tail for with a 10mmm brass nut. The pipe from the check valve appered to be an annealed 1/4" dia copper tube which was easily bent without losing cross sectional shape. While attempting to silver solder the tail to this apparent copper tube disaster happened, the tube melted at silver soldering temperature. Another unidentified material that is used for cheapness. So I had to make a complete copper tube that connects the check valve to the pressure switch. It is still WIP.

Brian

[runner42]

Today I managed to complete the installation of the new check valve, the most difficult operation apart from installing the check valve into the pressure cylinder due to an extremely tight thread, was the copper pipe from the check valve to the pressure switch. The existing pipe was some unknown material looking on the outside as annealed copper but definitely not but had the ability to be easily bent, my substitute hard copper pipe was much more difficult to match the complex curves due to the limited space in which to work. Having installed everything back, I was half expecting to be faced with some leaks, I am not a right first time mechanic, but hey it operated flawlessly and the original small leaks that caused the compressor to run continously was corrected. It now holds full pressure.

However, I am not using the compressor to provide the draught for firing the locomotive, since in the meantime I had slavaged a 12V motor from a mini compressor which was useless and incorporated this into a electric fan driven from 4 x 1.5V rechargeable D cells, providing 6v. This runs extremely well and provides a good draught. Using 12v running is too much like a gale, high vibration and noisey. 

Outside operation was not permissible because of the wild weather lashing Adelaide in the last four days, more rain and thunderstorms at tthis very moment. So much rain in December is unprecedented, especially given the fact that the BOM has forecast a hot and drier summer.

Brian 

[runner42]

I was over optomistic that my firing up woes are fixed. I have had two aborted attempts which failed because the fire went out. I don't know if the lack of draught to produce a good sustaining fire is due to electric fan I poduced or there is something amiss in the architecture of the firebox/grate or the over enthusiastic loading of combustible materials, that maybe constricting the air from the firebox to smokebox. These are kerosene soaked wood, charcoal and coal. In considering the electric fan the axial air flow seems sufficient, that is blowing out from the sides of the fan, whereas the vacuum caused at the input appears less robust, just sufficient to hold a piece of paper. I would like this to be more robust that can be detected by holding one's hand over the input pipe. The fan motor is a 12V type running on 6V, 12V running appears too severe. Maybe the size of the fan is too small, a possible modification. What attributes would one expect from a similar fan in terms of design criteria?

I have taken all neccessary steps to seal the smokebox so leaking should not be an issue.

Is loading the combustible materials an art form which requires patience to ensure adequate burning of the original before more is added? Only experience will overcome incorrect firing methods.

Any comments will be gladly received.

Brian     

[chris vine]

Hi Brian,

I just put bits of charcoal soaked in paraffin in the firebox to start with. Add a few bits at a time. If this won't burn, you certainly won't get coal to burn!!
After a minute or two, some bits of coal and more paraffin charcoal. More coal and less charcoal as it heats up.

If the flames are being drawn into the tubes, IE not back out of the firehole door, then I think you could have success with your current fan. If the flames just come out of the door, then you need more blow/suck.

Chris.

[cplmickey]

Hi Brian,

I echo Chris's words above. The fan doesn't need to draw very strongly, just enough to pull air through the fire. I start with wood and self-lighting charcoal (I used to use parafin but gave up on that) along with a household firelighter adding more charcoal as the fire gets going. Then I start to add small lumps of coal (beans) gradually, with carcoal at first, and then when well alight give it a good raking through and just add coal from then on. This is on my 5 inch loco, on the 7 1/4 I do exactly the same including adding the beans initially before moving onto small nuts for running.
Ian

[JonL]

I cheat. Firelighters, two chunks about the size of two oxo cubes. light those, fan on lowest speed. Charcoal on top, shut the door, whack up the fan. Once thats glowing Welsh steam coal on top,electric blower until about 30 psi, then steam blower. It varies depending on what I'm steaming (the club polly needs far more pressure before you can go to the blower, but I suspect thats the blower ring not being very good) but on the whole thats how I go about it.

[runner42]

Well I had success of sorts. I have convinced myself that the DC electric fan is sufficient, evidence by when the kerosene laden charcoal was ignited the flames showed that they were under draught and the resulting smoke billowing out of the chimney. However, the coal phase of the firing did not show a brilliant orange/red glow that I have noticed when viewing youtube videos on the subject. Mine was a more subdued orange glow. I did however, reach WP but it took some time to get there. The coal I use is the same as all club members.

It wasn't a successful run, because of niggling problems, one the blower valve was stuck shut and when I thought that I was opening it, it was merely the valve handle unscrewing. Secondly the injector did not work, it's the first attempt to use it so it maybe due to a number of issues other than the injector.

Brian 

[JonL]

Is the air coming up through the grate ok? I wonder if its getting around the fire rather than up through it.

[runner42]

As you can see the fire is not raging, too subdued to provide a comparitively fast steam up. I need an expert fire lighter to see what the problem is.


fire by Brian Leach, on Flickr

The DC blower appears to provide sufficient draught, by the flaming of the kerosene loaded charcoal.


dc blower by Brian Leach, on Flickr

Brian

[Cro]

I think it’s extremely difficult to say if it’s successful or not whilst the blower valve is not working, an electric blower does not give anywhere near as good a fire as a locos own steam blower so I would fix that first.

Secondly I would go and spend some time at your loco club and learn more about firing and driving these locos before attempting to steam it alone without fully knowing what you are doing to make sure you aren’t missing anything and know what to do.

Lastly, if you do steam it again. Take a video to share, photos really don’t show anything with this sort of problem.

I steamed out black 5 last weekend and takes around 30-35 minutes from cold to WP.

Adam

[JonL]

As per LBSCs instructions my Britannia has no cladding on the boiler. It took a while to steam up the other cold morning until I draped a heatproof blanket over it. Boom, up went the pressure.

[runner42]

Getting the blower valve unstuck was a fairly easy fix, so on the second steam up I brought the blower into operation at 30 PSI but found nothing was coming from ring surrounding the blast nozzle. This required removing the blower valve from the boiler, which again was relatively straightforward. But alas, removing the blower valve from the boiler introduced a significant stripdown need of the boiler and associated fittings. Removal of the blower valve invariably includes the blower pipe that passes from the backhead to the smokebox tubeplate, since the tube is screwed into the blower valve at the backhead end and a right angled threaded connection at the smokebox tubeplate. It was fortunate that the blower tube unscrewed from the smokebox tubeplate end and stayed in situ with the blower valve because I had in hand the majority of the items that make up the blower system. Applying HP air to the blower pipe confirmed that a blockage existed somewhere in the pipe or valve, the most likely being the pipe. Removing the pipe from the valve showed that the blockage is in the pipe. This was removed and again tested on HP air and on operation of the blower valve found to be operating correctly. The blockage was caused by over enthusiastic use of Locktite gasket maker at the screwed connection of the pipe to the blower valve. This stuff hardens and forms a seal but in this case in the pipe where it caused problems. 

Back to the initial statement concering the need for a major stripdown. The sequence of assembly of the blower system to the boiler is to undertake this before the steam transfer tube is installed because the flange at the smokebox tubeplate interferes with the right angled screwed connection to blower pipe. The blower pipe connected to the blower valve which is screwed into the backhead. With the steam dome cover removed and a light shone to illuminate the inside of the boiler the blower tube is captured by a thin rod pushed through the smokebox tubeplate and during completion of the screwing of the blower valve is guided to rest on the blower flange at that end. This enables the right angled connection to the blower tube to be made. 

To facilitate this the boiler/smokebox is removed and the smokebox separated from the boiler. This is a major stripdown. Also the steam dome cover is removed. The superheater removed and the steam transfer tube connecting the regulator to the wet header is removed.  I not bother to itemise everything because I am loosing enthusiasm to drag it out and I've probably lost many readers also. So I have included a part drawing showing the areas of the blower system that are easy to remove but difficult to re-assemble. A big job for the new year.

Brian 

blower tube by Brian Leach, on Flickr 

[dhamblin]

Excess sealant... I'm sure most of us on here have made that mistake at least once. Good bit of fault finding to identify it and although fixing might be a bit of a faff you'll at least get the loco closer to the finish.

Regards,

Dan

[runner42]

Recognising that my draughting may require a bit more oomph because of some unidentified reason I am revisiting the design of the blower system. One feature I am considering is the size of the holes in the blast nozzle blower arrangement. This is 4 holes of size drill no 70. This appears to me as being on the small size particularly when considering the environment in which it is placed, viz ash and soot in the smokebox perhaps could cause blockage.


Blast nozzle blower by Brian Leach, on Flickr

I have limited experience of this area of design but the two 3 1/2" gauge locomotives I have built use the same size hole, so if scaling up to 5" gauge should have a larger hole size. It maybe that the hole size is sufficient but does anyone have any experience with how much draught is required to maintain a vigorous fire? Let's say at 30 PSI boiler pressure would be translated to updraught with 4 holes size 70? 

Brian

[simon6200]

I put three radial 1 mm holes in the blower ring of my B1 Springbok. It works very well.
There was an article in one of the magazines about optimising blowers including hole size. Can’t remember which or when.