Water Gauge Glass is a complete liar? any tips?

[cncmodeller]

Having taken delivery of my new Accucraft Lew I've been doing some test steamings and have been going great but I am somewhat astounded by the unreliability of the boiler water level gauge, I tried popping in a strip of brass rod in case it was surface tension of the water in the glass but it isn't, I know a lot of us have got used to timing the run but it would be a lot easier to use the glass.
Any thoughts on this? anything would be much appreciated.

John

[Dr. Bond of the DVLR]

Are there bubbles forming in the glass or is it just reading too high or low?

If its consistently reading too high or low there may well be a partial blockage in the pipes connecting the glass to the boiler at the top or the bottom, or perhaps a steam leak out of the top one?

[rogero]

Check that the glass is not too long and partially obstructing the entry/exit of the top water passage - this was a problem found on some other models a few years ago (not Accucraft UK). Also rock the engine to and fro when cold, the water should easily rise and fall accordingly, if not try poking a wire into the water passages to check there is no obstruction such as sealant.

RogerO

[pauly]

I never trust my sight glasses so Im always topping my locos up little and often

[williamfj]

The blow down valve fitted to my Millie works well, whenever bubbles form or I'm not sure of the reading a quick blow sorts it out.

[Paul H]

Sight glasses are one design point I do not like about Accucraft's products. I think the top fitting should come off the boiler shell rather than the turret because the Goodall valve can introduce bubbles to the glass. In fact, the only sight glass I will even consult is my Archangel Princess which has a blowdown and seems to be quite accurate without use if the blowdown.

[JMORG]

My NGG16 reads 1/2 full after every lap of our circuit (baring in mind I fill it up and take out 30ml). I tend to just fill it little amounts, many times as it keeps the pressure up, because (unsurprisingly), it's train is always bigger than the damn loops!

[cncmodeller]

Thanks guys, Yes Rogero I did have the sight glass being too tall in the upper housing which I cut down but this was before this post! Also my gut feeling like Paul H mentions is that because the upper feed is from the Steam turret and I feel that the fact that the two inlets are of firstly unequal length and secondly one is attached to a dome this is where the problem lies, they are of differing volumes and it was interesting running it last night and seeing how just opening the regulator up and down how adversely the water sight glass is effected which of course it would if the top inlet is a dome.
It seems to me that the about average is that the glass reads 10mm too high all the time even when cold and no amount of tilting and rocking encourages it to read more accurately so I'm going have to use that as my yardstick.

[DVT Dweller]

I've had my Lew since December and had the same problem to start off with, showing half full then a sudden stop and pressure gauge drop along with that smell made me realise something was wrong.

I stripped out the gauge glass to find that the top fitting was being blocked by the glass. On further inspection the glass had fractured. Once I removed the fractured section this all fitted perfectly. Whilst doing all this I placed a piece of 1mm brass rod into the sight glass.

Since then it's worked, I wouldn't say perfectly, but it's a lot more reliable. I try to keep my boiler around half full , I find the best way is to add water, run for a minute or 2 and the level balances out. Then I can check if I'm happy or need to add abit more.

[steam4ian]

Rinse the boiler out with a bit of vinegar or citric acid.

On small gauge glasses capillary action can give false readings. I think the acid drops the surface tension as well as clears away scale.

Ian