Water column

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Johnny O
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Water column

Post by Johnny O »

Could someone please explain to me the use and application of a water column. I have read about them in literature but don’t understand the practicality of using one on my A 3 boiler. Should I consider using this devise or is it a “just nice to have” kinda thing.
Thank you for any advice.
curtis cutter
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Re: Water column

Post by curtis cutter »

It can be a very accurate way of measuring low pressures. 1 PSI of pressure will raise a water column 2.304 feet. So if you wanted 2 PSI of pressure then you would be looking for 4.608" of water column.

Gas pressure in homes is measure in "inches of water column". A normal pressure for residential propane would be 10.5 inches of water column.

I have no idea if this is what you are referring to so if I am off the mark I apologize for that.
Gregg
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K. Browers
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Re: Water column

Post by K. Browers »

Hello friends
I think Johnny O is referring to a water glass water column. These are basically a pipe connected to the back head of the boiler above and below the the waterline. the water glass and try cocks were then attached to this. The water inside the column would stay relatively calm compared to the circulation in the boiler so the reading of the water level in the glass would be stable.Here is a IBLS page that will give you more information. http://www.ibls.org/mediawiki/index.php ... ater_gauge

Happy building
Karel
Glenn Brooks
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Re: Water column

Post by Glenn Brooks »

Water columns are also called manometers when they are used to measure vacuum and rates of change in gasses. For example, I am using a water column to measure changes in vacuum in my (coal fired) smoke box as a proxy for improving draft by increasing front end performance- hence increasing my rate of evaporation (steaming ability) in the boiler. I suppose one could use the manometer idea to also monitor effectiveness of air brakes (or vacuum brakes) on the train consist.

One issue I found is that smoke box vacuum on our miniature boilers is fairly minimal. Hence I detected only around 0.4” of water column with my precious front end design. Once ai start testing the new install, I am estimating my improved Lempor evaluator blast nozzle and exhaust tube might raise the vacuum to somewhere between 0.6” - 0.1” WC. This would imply a 40% increase in boiler efficiency (steam production).

Just for FYI, WC readings below 1 PSI generally require an inclined manometer- or similar magnetic or digital instrument to measure the change. So if you find a need for such an instrument, be sure to look for one, or make one, that can measure these lower pressures.

Glenn
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Bill Shields
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Re: Water column

Post by Bill Shields »

a water column on a water glass is a way of connecting the TOP of the glass line to the BOTTOM of the glass line without going THROUGH the water glass to do it.

They can be useful to: 1> mechanically support the water glass so that is it more difficult to break and allow a pressure differential caused by bubbles and excessive flow between the fittings to allow a more accurate water level to be shown in the glass.

this is a good graphic:

https://www.google.com/search?rlz=1C1CH ... KlFoYiGGLM

sometimes the columns also have 'try cocks' on them so that you can manually check the water level should the glass blow out and need to be isolated
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makinsmoke
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Re: Water column

Post by makinsmoke »

Baldwin Locomotive Works 12-4A drawing courtesy of John Moore:
Water column.JPG
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makinsmoke
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Re: Water column

Post by makinsmoke »

As applied to Santa Fe 2-10-2 #940:
Water column resize.jpg
There is a a sheet metal and wire screen hinged cover over the sight glass as you can see. Its just to the left of the gauge light which is between the column and sight glass. it is a little harder to see the glass through the screen, but it is visible. It is also easily opened for a better look.

As Bill mentioned, there are try cocks on the column on the right side.

The fireman's side does not have a column, just the gauge glass installation more commonly seen on our models.
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kcameron
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Re: Water column

Post by kcameron »

Could a water column for the sight glass make up for weird placed connections to the boiler?

Right now my 1" Atlantic, steel boiler, has the top fitting coming off the top of the boiler about 4" above the inside top of the firebox. The bottom fitting is coming off about floor level of the cab, about 3.5" below the inside top of the firebox. The centering of the glass looks about right the bottom of the glass being just above the top of the firebox, less that 1/4" above I think.

I don't have the right three valve system for the sight glass. Yes I have cutoff valves for the glass, but the lower 'blow down' (below the cab floor) seems to be connected to one side of the tee from the boiler feeding the bottom glass cutoff valve. Meaning blowing down would always be wet coming from the boiler and not necessarily via the sight glass. The top cutoff is right where it comes off the top of the boiler but the bottom cutoff is right at the bottom of the glass.

My thought is if I fitted a column between the two fittings on the boiler, I could then install the glass with proper three valve setup much easier than trying to work around the current situation. I'm looking for comments on if this is a worthy idea to consider.
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Bill Shields
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Re: Water column

Post by Bill Shields »

It MIGHT help with your strange connection point.

In reality it is probably more trouble to make a water column than it will be to just bite the bullet and put the bottom connection where it needs to be.
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Glenn Brooks
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Re: Water column

Post by Glenn Brooks »

I think there is a previous, recent discussion of site glass placement here on Chaski that covers your very question. If I remember correctly, trainman added an entry that describes best practice for locating the blow down valves. Might be worth a search of the archives to locate the thread. Can’t be much help with that, as Iam drawing a blank about what key words or title the thread was originally posted. Might have been in a post about a 4-4-0 American running out of steam pressure- maybe...

One thing I am certain of is that if you relocate your sight glass, the bottom of the glass needs to just above the crown sheet. Which sounds like that is where it is presently located. Being that you have limited space available with 1” scale boiler, the existing plumbing might be the best you can do...

Maybe you could post a couple of photos for our Chaski boiler maker experts to see and evaluate if improvements could be done....

Glenn
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Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

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