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Discussion Starter · #1 ·
I am refinishing a locomotive and would like to update the sight glass to one with a line on it so it is easier to read. Looking for 3/16 or.200 OD.
Anywhere you can direct me will be greatly appreciated. Thank You Nick Jr
 
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Nick.
Red and blue-lined gauge glass in small Imperial sizes is becomming difficult to find. You can also get a similar effect using a piece of card or metal with a series of diagonal lines on a white background, positioned so as to be read through the glass. The diagonal lines will appear broken at the waterline.
 

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Discussion Starter · #3 ·
Curmudge, thank you for your reply. The enclosed pic is beautiful, and the water level is very easy to see. Unfortuantely I am only working with a tube and nothing as fancy as what is shown. But you gave me an idea, wonder if I just paint a line top to bottom on the back outside portion of the site glass will it give me a similar result?? Has anyone done that?? and are you satisfied with the results?? Nick Jr
 

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Discussion Starter · #5 ·
Jerry, you are right, the sight glass is so narrow that the accuracy is questionable at best. As long as I see liquid bouncing around I know I have some water still in the boiler. How did the decal hold up to the heat??? Nick Jr
 

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Nick Jr

Bruce Engineering (Polly) has 5mm glass (.197") in both plain and red line.
They have limited quantities of blue line glass but only in 4mm, 4.5mm and 6.5mm.
http://www.pollymodelengineering.co.uk/sections/bruce-engineering/docs/cat_oct08a.pdf
Thier online catalog is a 72 page .pdf file so it may take a while to load. Gauge glass is on page 52.

Maidstone Engineering has plain glass in 5mm and they have very fast turn around time.
http://shop.maidstone-engineering.co.uk/?mod=cat&cat_id=3&order=1

Cheers,
Walt
 

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Posted By Jerry Barnes on 01/17/2009 1:36 PM
I did the diagonal thing also, but made a clear decal out of it that I put onto the glass. Works great either way. Don't rely too much on the sight glass though, not all that accurate, I don't think.


Jerry: Did it work applied directly to the glass?
 
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Nick,
The picture is of a much larger scale loco, 5"ga IIRC, so there is the ability to include much more operating detail than in Ga1, but the principle is the same. If you want to have a go at painting the line on, which I have seen done successfully but not done myself, I would use a good grade of enamel, even nail polish might do the trick, but I'd also suggest using a lighter shade of red or blue than you would like to end up with because some enamels will darken from the heat.
 

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With my AC mike I have found the sight glass to be fairly accurate. I watch it and monitor it often. I see no reason to have a glass with any type of markings on it. When the glass shows the water right at the bottom of the fitting I shut it sown. Usually after a 45min run. When I drain the boiler I still have close to 1/2 cup water left. Later RJD
 

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Posted By aceinspp on 01/17/2009 4:42 PM
With my AC mike I have found the sight glass to be fairly accurate. I watch it and monitor it often. I see no reason to have a glass with any type of markings on it. When the glass shows the water right at the bottom of the fitting I shut it sown. Usually after a 45min run. When I drain the boiler I still have close to 1/2 cup water left. Later RJD


Markings behind the glass do not improve the accuracy, it improves the view-ability to make it easier to see the level.

I found that I have had the water level in the boiler too high but I could not tell if the glass was full or empty. Using the diagonal stripes shows the level by a reversal of the stripes where there is water in the glass. If the whole tube has reversed stripes, then it is totally full and so is the boiler, and if none of them are reversed then it is empty and so is the boiler. In between, it just helps to see the reversal in the lower portion of the glass.

A solid thin line painted lengthwise on the glass will show as a broad line (filling the width of the glass) where there is water in the glass, but you have to be at the right angle to see the line, i.e.: nearly directly opposite the line, or it doesn't show up at all.

The diagonal stripes, especially if mounted on a card behind the glass, and the card is wider than the glass, improves the angle of view-ability of the stripes, i.e.: you don't have to be right directly opposite the stripes and can be off to one side and still detect the stripes.

Also, by having the stripes behind the glass, instead of painted directly on it, you can see the stripes to the side and that is a reminder of which way the stripes are angled. If you can only see the stripes in the glass and don't remember which way they are supposed to be angled, you might mistake an empty glass for a totally full one.


The "accuracy" of the glass is dependant on the internal diameter and possible contaminants in the water. If it is a narrow glass the water may wick up the glass (capillary action) and provide a higher reading than what is actually in the boiler. Contaminants can make the water repel from the glass and show a lower level than what is in the boiler. Neither situation is good thing when playing with an expensive pressure vessel.
 

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Now thats worth trying it,:take the right diameter glassrod ca 8 inches or longer to a glassblower and let them expand the glassrod( the lenght in between the mounting lugs)make shure the openings on both ends are lined up.

Manfred Diel #1313
 

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Posted By lotsasteam on 01/17/2009 5:18 PM
Now thats worth trying it,:take the right diameter glassrod ca 8 inches or longer to a glassblower and let them expand the glassrod( the lenght in between the mounting lugs)make shure the openings on both ends are lined up.

Manfred Diel #1313


Be sure to re-temper the glass to handle the same pressure it was originally designed to do!
 

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There's an article by Charles McCullough in Steam in the Garden #97 describing, in detail, how to make and fit the diagonal stripe type to almost any type of water gauge .

Mike
 

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Nick add a pair of eye glasses then you can see it.


BTW Jerry lets see if you get it back faster than I got my fuel tank. Only took a year and half.

Later RJD
 
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