Water Sight Glass Position on a Vertical Boiler
- littleevan99
- Posts: 253
- Joined: Mon Feb 24, 2014 8:04 pm
- Location: Northern California
- Contact:
Water Sight Glass Position on a Vertical Boiler
I know on a horizontal boiler people like to keep the bottom of the glass 1/2"-3/4" above the top of the firebox. My question is, how much higher should the bottom of the glass be on a vertical boiler? I have it drawn at 2" on my plan I made, but I think it could be higher. The tubesheets are around 7.25" apart, should the bottom part of the glass be about halfway between that?
1.5" scale CliShay
1.5" scale 2-10-2T
2.5" 36 Ton Shay under construction
YouTube: http://www.youtube.com/user/littleevan99
1.5" scale 2-10-2T
2.5" 36 Ton Shay under construction
YouTube: http://www.youtube.com/user/littleevan99
-
- Posts: 1728
- Joined: Thu Jan 09, 2003 6:50 pm
- Location: Michigan, USA
Re: Water Sight Glass Position on a Vertical Boiler
I would put it even higher. Vertical Fire Tube boilers usually use the top third for steam space on your boiler. I would say to have the lowest reading of the water glass 4 1/2 - 5" over the crown sheet.
- steamin10
- Posts: 6712
- Joined: Sun Jun 08, 2003 11:52 pm
- Location: NW Indiana. Close to Lake Michigan S. tip
Re: Water Sight Glass Position on a Vertical Boiler
EDIT: Marty beat me on the post.
With this question, one must consider the dynamics of a fire tube upright boiler of low pressure, and its cooling ability of the tubes. Such boilers have tubes that run through the top tube-sheet in basically a flat plane, and depend on saturated steam to cool the last measure of the fire-tubes, as they extend above the waters contained therin. These boilers were common in stations and heating plants to provide low pressure steam, not only for heating, but for low pressure ventilation fans. There is a distinction between these heating boilers, and working boilers that ran cranes, and mill engines, with a noticeable rise in girth. They are constructed different, and have higher steam pressures. The working pressures are all over the board, and overlap to some degree. I want to note that I am unclear as to the specific time frames and history, or pressure grades of these units, so my sweeping statements, have to be taken with a degree of curiosity, to define the specific uses.
If you look at this class of boilers the top ends of the fire-tubes are submerged in a depressed (dished down) tube sheet, that mirrors somewhat the firebox and water leg end. This allows for a steam space at the head above the tubes, and that is where the water glass and safety valves occur. There are many variations to those designs, but the 'economy' styled boiler is meant for heating, and not driving equipment. For our modeling purposes, with the extreme overbuild we do, the likelihood of a tube failure form overheating is small, given we do not press our structures into such limits.
if one spends time looking at boiler adds form the early 1900's, you will find pictorial examples touted in the advertising.
I have a vertical fire-tube boiler, that is 10 inch diameter, with welded tubes. Intended for a Cli-shay, I will run it with about 1/4 - 1/3 steam space. That means the top of the sight glass will be at about 1/4 maximum height for the top, and that will serve as the steam collection area. Safeties and prime plug in the top tube sheet.
I hope someone has a better insight into these design functions for the age of steam, and can elaborate on this theme.
With this question, one must consider the dynamics of a fire tube upright boiler of low pressure, and its cooling ability of the tubes. Such boilers have tubes that run through the top tube-sheet in basically a flat plane, and depend on saturated steam to cool the last measure of the fire-tubes, as they extend above the waters contained therin. These boilers were common in stations and heating plants to provide low pressure steam, not only for heating, but for low pressure ventilation fans. There is a distinction between these heating boilers, and working boilers that ran cranes, and mill engines, with a noticeable rise in girth. They are constructed different, and have higher steam pressures. The working pressures are all over the board, and overlap to some degree. I want to note that I am unclear as to the specific time frames and history, or pressure grades of these units, so my sweeping statements, have to be taken with a degree of curiosity, to define the specific uses.
If you look at this class of boilers the top ends of the fire-tubes are submerged in a depressed (dished down) tube sheet, that mirrors somewhat the firebox and water leg end. This allows for a steam space at the head above the tubes, and that is where the water glass and safety valves occur. There are many variations to those designs, but the 'economy' styled boiler is meant for heating, and not driving equipment. For our modeling purposes, with the extreme overbuild we do, the likelihood of a tube failure form overheating is small, given we do not press our structures into such limits.
if one spends time looking at boiler adds form the early 1900's, you will find pictorial examples touted in the advertising.
I have a vertical fire-tube boiler, that is 10 inch diameter, with welded tubes. Intended for a Cli-shay, I will run it with about 1/4 - 1/3 steam space. That means the top of the sight glass will be at about 1/4 maximum height for the top, and that will serve as the steam collection area. Safeties and prime plug in the top tube sheet.
I hope someone has a better insight into these design functions for the age of steam, and can elaborate on this theme.
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
We have enough youth, how about a fountain of Smart. My computer beat me at chess, but not kickboxing
It is not getting caught in the rain, its learning to dance in it. People saying good morning, should have to prove it.
We have enough youth, how about a fountain of Smart. My computer beat me at chess, but not kickboxing
It is not getting caught in the rain, its learning to dance in it. People saying good morning, should have to prove it.
-
- Posts: 508
- Joined: Fri Oct 28, 2011 10:42 pm
Re: Water Sight Glass Position on a Vertical Boiler
Never mind the tube ends burning, the efficiency of heat transfer is much higher to water than to steam against the inside surface. We had a likamobile, and it steamed much happier with a nice and high water level rather than the 1/2 a glass that is normal for a loco style boiler. Steam dryness is the only real limit, you need enough height that the steam has some chance to separate from the water before it goes into the superheater (you are going to fit one, right?) The "express" style, with the ends fully submerged is much less prone to burned tube ends, and is more efficient than ones which have tubes that are not submerged. We have successfully melted silver soldered in tubes on a copper/steel boiler before now at the smokebox end...go figure that one out for a temperature of the flue gasses at that point. (that boiler used to afterburn too...) So, I would recommend submerged tubes, an adequate firebox depth, and lots of little tubes (about 1/2 the area per tube compared with a horizontal boiler)
James Powell
James Powell
- littleevan99
- Posts: 253
- Joined: Mon Feb 24, 2014 8:04 pm
- Location: Northern California
- Contact:
Re: Water Sight Glass Position on a Vertical Boiler
I moved the sight glass so the bottom fitting is 4.5" from the bottom tubesheet, and so that it's top fitting is .75" from the top sheet. If I kept the glass at half, there's where the 1/4 from the top sheet would be. With the way I run things, it shouldn't be all that hard to keep the water at half glass. When I measured the distance between fittings it came out to 1.875", that should be a good distance between fittings for it? I think having a glass that length should also encourage me to be more attentive to the water level then I already am when I've ran other locomotives.
1.5" scale CliShay
1.5" scale 2-10-2T
2.5" 36 Ton Shay under construction
YouTube: http://www.youtube.com/user/littleevan99
1.5" scale 2-10-2T
2.5" 36 Ton Shay under construction
YouTube: http://www.youtube.com/user/littleevan99
- Bill Shields
- Posts: 10546
- Joined: Fri Dec 21, 2007 4:57 am
- Location: 39.367, -75.765
- Contact:
Re: Water Sight Glass Position on a Vertical Boiler
carry an umbrella
Too many things going on to bother listing them.
- littleevan99
- Posts: 253
- Joined: Mon Feb 24, 2014 8:04 pm
- Location: Northern California
- Contact:
Re: Water Sight Glass Position on a Vertical Boiler
Bill, I'm guessing you're trying to say it's to high?
1.5" scale CliShay
1.5" scale 2-10-2T
2.5" 36 Ton Shay under construction
YouTube: http://www.youtube.com/user/littleevan99
1.5" scale 2-10-2T
2.5" 36 Ton Shay under construction
YouTube: http://www.youtube.com/user/littleevan99
- Bill Shields
- Posts: 10546
- Joined: Fri Dec 21, 2007 4:57 am
- Location: 39.367, -75.765
- Contact:
Re: Water Sight Glass Position on a Vertical Boiler
I did not say that...I am saying bring an umbrella.
I know what standard practice / design is for a vertical boiler.
I also know from experience how the top end of these things tends to bounce around as you go around the track (especially a 3/4" 0-4-0), hence you get a lot of wave activity at the steam / water interface.
For the Tom thumb, the bottom invert of the water-out line is BELOW the tube sheet by about 1/2", so I have to look at bottom of the steam exit and measure DOWN from there, not from the tube sheet.
After 10 years of running a 5" diameter boiler on our 3/4" Tom Thumb I know from experience that if I get the water anywhere NEAR that high, I get a lot of water carry over...and I need an umbrella...
One weekend at Long Island Live Steamers, one of our guest engineers got the water a bit high and since the stack is directly above the tubes, the carry-over ran down the tubes and actually put the fire out. She is now affectionately known as 'high water....'
You are gong to have to experiment to see what works for your individual boiler / design / situation.
I would put the bottom fitting a bit lower, and come UP from there on a short piece of pipe to the glass so that you CAN move the glass down a bit without having to rework the boiler.
I run the Tom Thumb with about 1" of water minimum (bottom of glass) on the tube sheet and all has been well for 10 years of really hard running...the inside of the firebox looks as good as the day Jim soldered it..which isn't too bad considering he was going blind at the time.
I know what standard practice / design is for a vertical boiler.
I also know from experience how the top end of these things tends to bounce around as you go around the track (especially a 3/4" 0-4-0), hence you get a lot of wave activity at the steam / water interface.
For the Tom thumb, the bottom invert of the water-out line is BELOW the tube sheet by about 1/2", so I have to look at bottom of the steam exit and measure DOWN from there, not from the tube sheet.
After 10 years of running a 5" diameter boiler on our 3/4" Tom Thumb I know from experience that if I get the water anywhere NEAR that high, I get a lot of water carry over...and I need an umbrella...
One weekend at Long Island Live Steamers, one of our guest engineers got the water a bit high and since the stack is directly above the tubes, the carry-over ran down the tubes and actually put the fire out. She is now affectionately known as 'high water....'
You are gong to have to experiment to see what works for your individual boiler / design / situation.
I would put the bottom fitting a bit lower, and come UP from there on a short piece of pipe to the glass so that you CAN move the glass down a bit without having to rework the boiler.
I run the Tom Thumb with about 1" of water minimum (bottom of glass) on the tube sheet and all has been well for 10 years of really hard running...the inside of the firebox looks as good as the day Jim soldered it..which isn't too bad considering he was going blind at the time.
Too many things going on to bother listing them.
- littleevan99
- Posts: 253
- Joined: Mon Feb 24, 2014 8:04 pm
- Location: Northern California
- Contact:
Re: Water Sight Glass Position on a Vertical Boiler
Ok Bill, I thought you were implying earlier that the glass was up to high. I see what you mean about the vertical boilers and the carry over on that one. I am going to put the steam out of the boiler fitting on the top tubesheet, and have 1 or 2 copper coils that make their way around the smokebox to the engine. I'll have to tell my grandpa to bring an umbrella for his new TT when it's eventually finished!
1.5" scale CliShay
1.5" scale 2-10-2T
2.5" 36 Ton Shay under construction
YouTube: http://www.youtube.com/user/littleevan99
1.5" scale 2-10-2T
2.5" 36 Ton Shay under construction
YouTube: http://www.youtube.com/user/littleevan99
- littleevan99
- Posts: 253
- Joined: Mon Feb 24, 2014 8:04 pm
- Location: Northern California
- Contact:
Re: Water Sight Glass Position on a Vertical Boiler
Well, after placing some PM Research angle valves on my 1:1 drawing, I realized that 1 7/8" wasn't emough distance between the two fittings. I think I'm gonna change it to 2 3/8" or 2 1/2" so after I add the packing nuts, I can still see the water level easily.
1.5" scale CliShay
1.5" scale 2-10-2T
2.5" 36 Ton Shay under construction
YouTube: http://www.youtube.com/user/littleevan99
1.5" scale 2-10-2T
2.5" 36 Ton Shay under construction
YouTube: http://www.youtube.com/user/littleevan99