# Accucraft Blow-down Misadventure



## RP3 (Jan 5, 2008)

OK you steam experts out there. Here is a challenge for you. I recently bought a new Accucraft Butane fired D&RGW C-25. One of the great new additions to this locomotive is a water glass blowdown. It here's the thing: when I open the valve, water/steam come out, but nothing moves in the water glass. So if I have a bubble, it stays put. The blowdown is connected to the bottom of the water glass by a banjo bolt. So apparently the flow is only coming from the lower connection between the water glass and the boiler. Water glass is functioning properly and water rises or falls as boiler steam is consumed. But no matter what, opening the blowdown will not clear the water glass.

Yes, as in most Accucraft locos, the water glass is too small in diameter and will easily trap a bubble (my case in spades). But another Acc. loco that has a DJB blowdown works perfectly. 

I haven't torn down the water glass yet, but I may be forced to do so to look for any restrictions. But I would like to be sure what I am looking for first.

Ideas anybody?

Ross Schlabach


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## Taperpin (Jan 6, 2008)

Ross.
The blow down is drawing water from the boiler connection[passage ] rather than the glass passage, it flashes to steam as soon as the water exits, dismantle and open out the passage to the glass.


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## Kovacjr (Jan 2, 2008)

Ross, I'd check the top banjo fitting. Thinking it may be plugged or blocked.


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## Charles M (Jan 2, 2008)

Sometime back I reworked an Accucraft K36 with a water glass problem. It wouldn't read correctly and never showed water usage . Turns out the water glass tube itself was cut too long and blocked the upper passage . No water flow through the tube.
Shortened the glass and it fixed the problem. 

Charles M SA#74


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## RP3 (Jan 5, 2008)

All three suggestions are excellent and I will explore each. This blowdown is odd, at least in my opinion, by having as its connection to the water glass another banjo, so I will also check that one for restriction.

So the cab will come off tomorrow - enabling me to have a clear shot at the whole water glass system.

My money is on a too-long glass partially blocking the top fitting. But overall, I find the entire system should be opened up with larger passages and a bigger diameter glass. We'll see, and thanks again.

Ross Schlabach


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## Bob in Mich (Mar 8, 2008)

Ross I change My water Glass to 9mm ,they are more accurate.


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## clifforddward (Jan 2, 2008)

Ross, can you take a photo of the water gauge before disassembly to show us all? It's pretty obvious the water is pulling from the boiler rather than the glass tube, but I'd like to see the overall water gauge to understand the design.

I don't think Accucraft has any real understanding of best practice for water gauges...have seen all sorts of issues related to restrictions for water flow.


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## RP3 (Jan 5, 2008)

Yes Cliff,

When I get back down in the shop and can peel off the cab, then I can make a picture of the offending appendage!

Ross Schlabach


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## Larry Green (Jan 2, 2008)

A few years ago, I purchased a Roundhouse Forney that had never been steamed and sat on a shelf for at least ten years. After giving the engine a visual checkup, suspecting dried out seals/gaskets, and snugging up on what was obvious including the water glass nuts. Aside from numerous leak elsewhere, no water showed in the glass. Just some vapor clouding.
After disassembling the entire glass assembly--the bottom leg went below the cab floor to a banjo fitting beneath the boiler--a hard white material was found to be clogging the lower water passage. My best guess was solidified silver solder flux that had never been flushed out and that had settled in the bottom of the boiler, then been forced into the lower water passage by the pressure of the boiler's first steaming
After cleaning out all of this gunk, the glass has performed as well as can be expected from such a small tube.
RH has started using an entirely new design of glass--a cast bronze assembly silver soldered to the left side of the boiler. this has a comparatively large chamber milled into it, with a flat quartz plate cover. The two that I have seem to be bubble-free and easier to read.

Larry


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## RP3 (Jan 5, 2008)

I have removed the cab and taken a picture which is (hopefully) attached. I went ahead and dismantled the whole water glass and blowdown system. There were no blockages and the glass did not interfere with water or steam flow. I did discover that the bottom of the glass was broken but not enough to cause any problems. I chased out the water passages as much as I dared and replaced the glass with one that has a larger inside passage, and that could have been a restriction to flow from the upper pipe that connects to the turret. The bottom T fitting is unusual. Picture the T lying on its side with the glass coming in from above - like you see in the photo. That puts the glass into one extension of the top of the T. This part of the T is wider inside to admit the glass, but it steps down which keeps the glass from blocking the vertical line in the T which extends into the boiler. The other extension of the T (facing down in the photo) has a smaller water passage which is cross-drilled to allow the steam to exhaust out the blowdown.

If you've followed all that, I think that the glass itself was too small inside and so when the blowdown was opened, the steam would flow from inside the lower boiler connection, right out the blowdown. My guess is that if the blowdown came straight out the bottom of the lower fitting of the water glass ( instead of thru this odd banjo arrangement), then the flow out the blowdown would be straight thru the glass instead. I wonder if the Bernoulli principle is at work here?

Since I doubt my ability to rework the bottom T pipe to allow a straight through blowdown (which would also involve drilling another hole in the cab floor and finding a straight thru globe valve to fit, my current plan is to replace the crappy T handled fitting at the end of the blowdown with a globe valve (ideally a straight thru one).

Further comment from the experts is gratefully anticipated. Gordon, Jay, Cliff: what have you got for me?

Ross Schlabach


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## Ray Cadd (Dec 30, 2008)

Hm...I'd be willing to bet it's the glass diameter that's causing the problems. Let us know, of course.

I've been thinking of adding a blowdown to the gauge glass on my Emma..


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## Kovacjr (Jan 2, 2008)

What are the ID passages? Id make sure they are all 3mm. This is the ID of the 5mm glass I sell. 1mm wall Pyrex.

Does the lower banjo bolt come near the passage? I would use a 90deg valve in the cab with new plumbing to the lower glass, then route the outlet to the hole. You cant access the lever anyway where its at. A real pain in the ass.


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## Semper Vaporo (Jan 2, 2008)

The valve on the end of the pipe from the lower fitting appears to be one that requires more than a 1/4 turn to open it very far... probably like 3 (or 4) quarter turns at least if not more... That is more like a "drain valve".

The one on the bottom of the oil reservoir appears to be a 1/4 turn ball valve.

To get water to flow out of the sight glass I think you need to be able to open the valve quickly. To drain the water from the oil reservoir you have plenty of time to twist the valve open, so that type of valve would be okay, but the blowdown needs to be the 1/4 turn ball valve so it can open completely in a big hurry.

I think I'd try to find a way to exchange those two valves!


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## Steve Ciambrone (Feb 25, 2014)

If the lubricator and blow down valves are the standard Accucraft thread you might be able to swap them, or the 1/4 turn valve that is sold separately for a lubricator drain should fit also.

Steve


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## RP3 (Jan 5, 2008)

Thanks for all the ideas. First, I'm adding a drawing so folks can see what the inside of the bottom fitting looks like. Next to the questions and comments. All the passages have been drilled out as much as I dare and are more than 3mm ID. I replaced the glass with a slightly larger one that has a bigger ID too. So far, the best idea is to make a 90 degree fitting that I can screw onto the bottom of the lower fitting - one that lets me drill out the bottom of the fitting and cover up the cross-drilled banjo bolt holes. The tough part is clearance to screw this all into place. And then I still have to deal with finding a small enough straight-through globe valve and having room to fit it.

The 90 degree lever valve looks like an ideal switch, but these things (at least the Accucraft ones) leak. Since steam oil is thick, it doesn't leak much. If I switched it to the blowdown, I expect the leakage would be much worse.

Ross Schlabach


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## John Allman (Jan 2, 2008)

Ah. here is a dumb idea, but would work. Flip the blowdown so its on the top of the water glass and lengthen the drain pipe. 
Sure it wont drain the boiler, but so what? that is not totally necessary anyway. Plus the way it is doesnt drain the whole boiler either.

but it will clear the glass every time.


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## John Allman (Jan 2, 2008)

you're welcome Ross. Anytime you need dumb ideas, just let me know


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## RP3 (Jan 5, 2008)

OMG, John! Why didn't I think of that? It is so obvious. Just brilliant! I'm not worthy.

Ross Schlabach


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## Chris Scott (Jan 2, 2008)

John Allman said:


> Ah. here is a dumb idea, but would work. Flip the blowdown so its on the top of the water glass and lengthen the drain pipe.
> Sure it wont drain the boiler, but so what? that is not totally necessary anyway. Plus the way it is doesnt drain the whole boiler either.
> 
> but it will clear the glass every time.



Not sure that's such a good idea. If you move the valve to the top it would be a blowup valve. Who wants to blowup their locomotive? 






Just could not resist.


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## RP3 (Jan 5, 2008)

Ah, yes! All the expert help I'm getting. It's overwhelming.

Ross Schlabach


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## seadawg (Jan 2, 2008)

If you put it on top, it will be a blow up valve or maybe even a http://forums.mylargescale.com/18-live-steam/7434-schwinky-valve.html


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## roadranger (Jan 6, 2008)

I could never understand these model live steamer sight glass blowdowns. They are nothing like whats on full size steam locomotives. On the full size sight glass, the top and bottom sight glass connections to the boiler have shutoff valves on them. 

To properly blow down the glass, the bottom glass feed valve is closed, the top glass feed remains open, and the blowdown is opened up letting steam blow thru the glass cleaning it of crud and showing that the top sight glass spindle is not plugged up.
Then the top glass valve is closed and the bottom valve is opened up and then the blowdown is opened. The water blowing out shows that the bottom sight glass spindle is clear and opened. To finish up the blowdown valve is closed and the top sight glass valve is opened up all the way. Make sure BOTH top and bottom valves are opened the the way up.

To blow down a sight glass requires running steam from the turret thru the sight glass and out the blow down valve. I don't understand how a sight glass with no shutoff valves top and bottom can be blown down.
Basically when you open the sight glass blowdown on these models you are just opening up a boiler drain, NOT a blowdown.

So at the very least, install a shutoff valve on the bottom sight glass feed so that you can shoot steam from the turret thru the sight glass.


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## RP3 (Jan 5, 2008)

Hi Roadranger,

Your info about the full-sized water glass was very interesting. But implementing multiple shutoffs is more than a little tough in the tiny cab of a 1:20.3 locomotive. There is no room in this cab because of the location of the steam lubricator. So we're limited to what we can put under the cab.

Ross Schlabach


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## Pete Thornton (Jan 2, 2008)

> The 90 degree lever valve looks like an ideal switch, but these things (at least the Accucraft ones) leak.


They claimed to have fixed them (after I complained.) The originals had no sealing washer, but they added some in the latest iteration. 
Disclaimer: I have no idea whether the latest ones still leak - mine is an original type with my own washers fitted.


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## RP3 (Jan 5, 2008)

Hi Peter, I was thinking about swapping the valves, but the lever one is letting steam oil dribble out - not much but enough to make it suspect for steam, Chris Sortina who works with Accucraft says he showed the folks in China how to lap these, but I expect as soon as he left, they went back to their own way of doing things. Sigh!

Ross Schlabach


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## clifforddward (Jan 2, 2008)

Ross:

Wanted to think about this one for a couple of days. As you mentioned our little sight glass water level indicator blow downs cannot work like the full size prototype due to inability to scale the fittings....so it is a "modified" blowdown. As such, I believe when the blowdown valve is opened then the water flows out rapidly causing the captured bubble creating the reading problem to flow out of the tube with the water...not perfect but good enough in most situations.

I think the problem with this one on your C25 is that the blowdown valve makes use of a banjo fitting....an excellent fitting for steam such as when used on a whistle, blower or for main locomotive steam line, but somewhat problematic for high speed hot water flow...the flow is interrupted and slowed down....therefore the water flow comes from the course of least resistance, and in your case is coming from the lower boiler fitting and the boiler rather than from the glass tube...because this happens the bubble in the glass tube is not pulled out of the glass.

Need to think about how to fix the design...perhaps the easiest fix is to replace the banjo fitting with a direct globe valve...although I'm not sure if you'll have easy access to the valve that way.....that's the first thing I would try...maybe work cobbling something up to test with the cab off to see if that fixes the issue.

We can also talk more next month when we are both together at Jim's and the ECTS in York.


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## Chris Scott (Jan 2, 2008)

Left is a Accucraft Draincock: AP21-613









Right is an Accucraft Needle Valve











Accucraft majority pipe fittings, bushings, etc., threads are Metric M5x0,5. 
Regner (Germany) offers wide range of M5x0,5 thread pipe fittings
Jason, The Train Department is a Regner Dealer.
This is the Regner Katalog, pg 41-47 pipe fittings. 
https://issuu.com/regnerdampftechnik/docs/regner_katalog_2017/2?ff=true&e=27390833/56209082 
(Link is a little wierd, you have to backup a page to see the cover. (?) )

To interpret (without translation) the Regner Catalog you need 4 things;
a. picture
b. thread
c. part number
d. price (use exchange calculator)
Then talk to Jason. 


Water Glass Fix Options
1. Globe Valve Below the FloorBoard;
Replace the Site Glass bottom Banjo Fitting and Banjo Bolt with a Regner Globe Valve (Straight through or Right Angle) M5x0.5 directly. You will have to drill a hole in the floorboard for an extension pipe and Globe Valve below the floorboard. The extension pipe will have to be assembled with other Regner fittings that might not be designed for such a purpose but a little creativity goes miles. You will need M5x0,5 Stop Nuts to put the fittings together in the limited space below the floorboard.



















2. Globe Valve Above the FloorBoard;
Replace the Site Glass bottom Banjo Fitting and Banjo Bolt with a Regner Globe Valve. 
It's possible but a lot more complicated in the numbers and types of Regner pipe fittings to adapt. Better to leave this option alone unless you are absolutely opposed to drilling a hole in the floorboard.

3. Replace the Sight Glass entirely with a Regner Sight Glass. Page 43 Regner Katalog. 
You will also need some other pipe fittings to put this together. 

One option has a blowdown built in with M6x0,75 thread. Using this would But it seems you might need a Regner thread reducer from M6x0,75 to M5x0,5 threads

*Jason can fulfill all your Regner needs and wants and probably help with the assemblage.*


Examples of adapting a Regner Pipe Fitting
1. If you skip the Nut/Ferrule you have an Extension Pipe or a M-M Coupling.

















2. Need 2 steam taps off the back head but Accucraft only gave you one.









3. Coupling F-F; M5x0,5 - to - M5x0,5







(Each end is HEX)

Regner Nuts to use as pipe fitting's Lock Nuts (actually a lot thinner in real life.)


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## RP3 (Jan 5, 2008)

Hi Chris, ought about using Regner parts but there were two things inhibiting this solution. First there is no room under the bottom of the water glass to attach any of the Regner fittings. Second and more important the size of the Regner valves prohibit their use. I have samples of both valve and they protrude too far and are too large for a suitable installation. But thanks for trying.

Ross Schlabach


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## Chris Scott (Jan 2, 2008)

RP3 said:


> Hi Chris, ought about using Regner parts but there were two things inhibiting this solution. First there is no room under the bottom of the water glass to attach any of the Regner fittings. Second and more important the size of the Regner valves prohibit their use. I have samples of both valve and they protrude too far and are too large for a suitable installation. But thanks for trying.
> 
> Ross Schlabach


Maybe someone else can see the madness and help the discussion.

I was thinking of boring a hole in the floor, Removing the banjo and bolt, feeding an extension from the bottom the globe valve attached under the floor and a bunch of other stuff - just to add a little more idea flushing. Or, Accucraft routed the banjo pipe to a different location maybe there is a kernel of an idea there.

Best of luck with your challenge.


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## TLR (May 9, 2015)

Just an idea can you put the pipe to the drain valve above the banjo, can't quite see is the banjo pipe soldered to the boiler or screw fitting if a screw fitting then a pipe could be fabricated to allow the sight glass to remain in the same position.

Shaun


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## du-bousquetaire (Feb 14, 2011)

I have a friend who solved the space problem by having the valve under the cab where it is accessible and can represent some of the plumbing between loco and tender. Just pipe up from the bottom of the sight glass to a valve under the cab. I beleive he uses a sort of whistle type valve for that where he just pushes down on a lever to clear out the water level. It springs back after to close. However I haven't tried it yet and I think that you have to be a pretty good machinist to have a valve that shuts tight.


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## RP3 (Jan 5, 2008)

Thank you for the suggestion, but we have already determined that I can not drill straight thru the floor since there is a large brake cylinder below the cab floor. There already is piping to a screw valve under the floor at the rear of the cab, but this system is not clearing the glass - the reason for my initial inquiry. 

Currently, I am having a special water glass made with upper and lower shutoff valves as well as a blowdown valve to insure that I can clear any and all bubbles. Hope to see it at the ECLST next month.

Ross Schlabach


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