Straining the Rubbish

An earlier article has described Sentinel 7109's boiler feed pumps including the cab-mounted one on the right hand side.

Original Cab-mounted Boiler Feed Pump

The pump has to draw water from the water tank via pipework and a coarse strainer situated in a right-angled fitting and isolating valve housing just in front of the cab.

Strainer and Valve Housing by Water Tank

The picture below was taken just after Sentinel 7109 arrived at Midsomer Norton Station in December 2004. It shows how scale and rubbish accumulate at the bottom of the tank. The pipe at the bottom of the picture is the take-off for the cab feed pump. It does not suck directly from the tank bottom and so not too much detritus should be drawn. However, to be safe rather than sorry, the strainer is included. (Another in-line strainer may also be added at the pump inlet).

Bottom of the Water Tank

Since the above picture was taken, much of the scale and rubbish have been removed using a domestic vacuum cleaner (honest!) with a long hose to reach in from the top. Some chemical de-scaling may also be necessary in the future depending on how 7109 reacts to water treatment. An awful lot of Kilrock-K is needed for this type of kettle!

Coarse Strainer Housing

The strainer housing is shown above. When it was first opened, a rather distorted, vaguely cylindrical-shaped, perforated, oxidised, copper thing came out. On trying to reform it into shape, it was obviously going to break and eventually it did.

However, since it was already broken, there was no harm in at least trying to fix it.
I heated the parts to red heat and quenched them in cold water to anneal (soften) them. Then I did the reshaping using a rubber mallet, a 4lb hammer as behind support and a broom handle about the right internal diameter.

I then silver soldered the pieces together as in the picture below.

Repaired Coarse Water Strainer

Hopefully I haven't blocked too many of the strainer holes and it may work better in some orientations than others. However, I think we have a strainer capable of going back into service again!