Water level problem

[grandfathertyke]

I'm not very experienced in ME and so would appreciate some advice on a problem I have encountered with my 5 inch gauge Titch. I've just fitted the boiler, a professionally made one, and the loco is steaming and running very well indeed. The problem lies in the water level as indicated in the glass.

As water is used, the level drops, but no amount of pumping or running with the axle-pump on will get the level to come much above the bottom nut. After a while like this, the loco shows signs of priming. I've stopped running at that point, let it cool down and then taken off a safety valve to check the level in the boiler, to find that it is actually very high, almost covering the crown, yet still showing just above the bottom nut on the water gauge. As the boiler cools, the water level in the glass rises. Can anyone advise me as to what is happening with the sight glass? I'm nervous about running the loco not knowing even roughly what the water level is.

Many thanks in advance,

Frank

[houstonceng]

Hi Frank

Sounds like the sight-glass fitting on one end is blocked. Did you use PTFE tape to seal the thread ? A common problem is that, as the fitting is screwed in, a bit of tape covers the hole and thereby stops the water entering the glass. Steam pressure on one end (top) may depress the level and the water can't re-enter as there's a pressure differential.

Just a thought.

If you haven't used PTFE tape, the next two things to check are that the seal used on the glass hasn't blocked the hole and - don't laugh, because it has been missed on fittings - that the fitting have been properly drilled out.

[grandfathertyke]

Thanks for the prompt reply, Andy; much appreciated. I'll check these things out and then let you know what has happened.

Frank

[pault]

Hi Frank
I think that Andy is right, the top fitting is blocked or partly blocked

Regards
Paul

[steam4ian]

G'day Frank

Don't run the loco until you are sure you know where the water level is. 3 boilers at my club in the last two years, one with a very experienced driver. When I drive other's locos I watch the water like a hawk and won't take charge until I know and work every means of feeding the boiler, drives the owners nuts, they just drive.

You mentioned "just covering the crown". If the boile is full to priming you should have the level close to the underside of the outer wrapper.

As the others have said, check the gauge.

Did you blow the gauge down and watch the water level?

Good luck
Ian

[grandfathertyke]

Hello Ian,

Thanks for your reply. Yes, I did blow the glass down but the result was just the same-level just above the bottom nut. I envy you in Oz; it's just too darned cold, wet and snowy here to do much running, so plenty of time for the workshop to sort this one out.

All the best,

Frank

[ejparrott]

Sounds very much like a problem with the water gauge fitting. I inadvertently partially blocked one on my Hunslet at last service. Didn't worry too much about it then because it has 2. Hopefully sorted it out this winter though.

[grandfathertyke]

Following the advice given above, I looked at the gauge fittings for signs of a blockage and found none. There was no excess jointing, O ring extrusion, or anything else. The water gauge itself has equal size passages, top and bottom, of 5/32 Dia., with a gauge glass of 3/16 O/D. The top gauge fitting, which is silver soldered to the outer wrapper, has a connecting hole drilled into the wrapper of 7/32Dia.

The drawing for the new boiler on Titch was scaled up from the 3.5 inch version. The small Titch water gauge has a glass of 5/32 O.D. with top and bottom water passages equal at 3/32 dia. The top fitting has a drilling into the wrapper of 5/32 Dia.

A scaling factor for gauge conversion, from 3 1/2 inch to 5 inch gauge works out at 1.33'. and the dimensions are about right according to this. But as I have tested this, with the problem I have outlined, I wondered if this is too simplistic? One thought is that an increase in size of the top fitting drilling might help, but I am not sure. Any ideas most welcome!

Thanks in advance,

Frank

[Deleted]

You say you've checked the fittings, but have you checked the water ways into the boiler?

From your description, the top bush is a right-angled fitting soldered into the curve of the outer wrapper. This is often used on a round-topped boiler to provide a longer glass. However, it could be blocked with solder and being right-angled, it's very difficult to prove the way is clear with a wire.

This may sound silly, but try filling the boiler with the glass removed. When water comes out of the bottom fitting, put your finger over it and continue filling. Then watch for a steady flow of water from the top fitting when the boiler is full.

[ilvaporista]

Another one to watch is the length of the glass tube, make sure that it leaves the hole to the upper fitting open.

[grandfathertyke]

I've checked the flow out of the top fitting and it is unimpeded, so apparently no problem there. I'll check the length of the glass tomorrow to try to rule that one in or out. I'm also beginning to wonder about the dimensions of the glass itself. The fitted one, scaled up from the 3.5 gauge drawings, is 3/16 o/d, .136 i/d . Martin Evans specifies 1/4 o/d on his 5 inch gauge locos, so could this be the problem??

Any opinions gratefully received.

[houstonceng]

It really dopesn't matter what the scale of the loco is, so long as the glass has sufficient bore diameter. The water isn't affected by the scale of the loco !

The bore of the glass will have only one effect and that is, the smaller the bore the higher the liquid will appear above its actual level in the boiler. Capiliary action. In some published designs with small bore glass, the level can appear above the bottom nut when the firebox crown is exposed.

Small passages in the fittings can cause the level to bounce more than usual - either by the boiler vibrations from undulations in the rail (locos) or ground (traction engines), or from the boiling of the water.

[Boadicea]

Frank, I find, the bigger the better - easier to see and, as houston says, less bounce. I did fit 8mm to a 5" loco once. It did not look right, but it was really good in use.

I have 5" locos fitted with 5mm glass and 4mm with no problems. Many manufactured fittings, perhaps the majority, are 5mm.

Of course I am talking OD here and it is ID which matters, but I think this is not your problem.

Can you remove the fittings, reassemble in exactly the same way on the bench and see what the waterflow is through them?

Afterthought - did you test the top fitting exactly as superseven said, and not just removing the top fitting and checking it? There is a possibility the top fitting, when screwed in, fouls something inside. It could even seal quite nicely inside, aided by the PTFE tape/sealant.

[peterseager]

Could it be that the fitting on top of the boiler, into which the top fitting of the water gauge screws, has a tube dipping down inside the boiler. This would cause the gauge to stop working when the water level reached the bottom of the offending tube but would pass supersevens test with the gauge removed.

Peter

[grandfathertyke]

Thanks for all the advice, chaps. I've checked a few more things out, and there is definitely no pipe inside the top fitting running down into the boiler. No PTFE tape was used in the fittings, and the jointing compound used has not fouled any holes. As well as testing top and bottom holes with water, they have also been thoroughly poked through with wire and are clear. Still to do is to assemble the glass on the bench and see what the flow is like there. After that, the only recourse I can see is to try a 5mm o/d tube and fittings, and see what happens.

Frank

[jma1009]

Frank,

sorry to hear of the water gauge problems.

can you post a pic of the gauge please?

i dont suppose it's a commercial 3-cock gauge? i had to sort out a problem with a commercial gauge of this type on a commercial 7.25"g loco 2 years ago... the bottom water cock had been incorrectly assembled or altered and was actually closed when the handle position indicated open...and had the same symptoms yours has (which only occured when in steam).

the other checks recommended above are excellent advice.

cheers,
julian

[Deleted]

Hello chaps--------- not trying to be a harbinger of DOOM etc but take a look at this, and especially the heading "Operational Failures".... These are well known events in today's railway world but just goes to show what can happen--- even with the best intentions in mind }--------- en.wikipedia.org/wiki/USATC_S160_Class -----------

[grandfathertyke]

That's why I want to get it sorted! Sitting behind and in close proximity to a boiler of uncertain water-level makes me just a little uneasy. I've been more or less intact for the last six decades, and would like that to carry on!

Frank

[jma1009]

hi frank,
you also need to check the depth that the bushes protrude into the boiler...ideally they should be flush with the inside of the backhead, and outer firebox wrapper if there is an 'elbow' fitted for the top connection.
the bottom fitting when screwed in should not protrude beyond the depth of the bush, and the top fitting when screwed in must not obstruct the bend in the elbow.
the top fitting can have a slightly smaller hole through it compared to the bottom fitting, so the sizes you have quoted should be ok, so long, as others have noted, there are no blockages or restrictions anywhere.
cheers,
julian

[grandfathertyke]

Thanks Julian, I'll check this out. I've tried to add the picture you asked for. Hope it works!

Frank

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