Sunday, 31 May 2015

Vacuum Braking (13) Implementation (7)

Sunday May 31st 2015 has been mainly about the vacuum braking pipework but not entirely.

In my last article, I'd begun to assemble the vacuum ejector pipework. Now I've pretty well completed it as shown below.
Steam supply linked to the Ejector
The main work was either side of the blue pressure reducing valve (PRV).
PRV, condensate drain valve and unions at either end
Both upright ends had to be parallel in order to mate with the union counter parts. (If I've not said before, unions allow the pipework to be taken apart and also enable rotation).

In the above photo, there are unions at each end of the pipe but, in the first photo, the upright larger diameter pipe also has unions allowing it to rotate. In this way, the distance between the PRV and ejector has been made non-critical and hence much easier to assemble.

The next task was to add some support for the vacuum hoses. Previously the 'Swan necks' on the buffer beams had left only a short length of pipe to attach the hose. I'd felt that some extra length was needed in case the hose could lever itself off.
Lengthened 'Swan neck'
The extension was made from a straight pipe coupling and spare male threaded pipe. The threads were sealed with Heldite.
Comparison with usual hose attachment
The extension is still a little short compared to a normal hose fixing. However, if there is a tendency for hoses to come adrift, the extension can be extended further to fix the problem!

Some time ago, I decided that I wanted to take the steam supply for the whistle and pressure gauge from the safety valve assembly instead of the two outlets at the ends of the four-way manifold which feeds the superheater. It saves one expensive isolating valve and make the valve actually reachable by hand!

I thus had to block the manifold outlets. I used a heavy duty steel cap for one end and a coupling and plug for the other (I had the cap already and I couldn't get another off the shelf).

Since these items were round, I was advised that a Stillson wrench was the best way to tighten them despite the likelihood of some surface damage in the process.
Screwing it up!
To ensure a good seal, I made a pair of thick annealed copper washers and applied a liberal amount of Steamseal to make sure.
The cap fits
The Plug fits!
Now to make a hole in the roof for the ejector exhaust.

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