Chapter 7: - Driving Practices
Priming is generally due to one or more of the following
causes: -
•
Dirty boiler plates
•
Dirty boiler water
•
High water level in boiler
•
Blowing off at the safety valves
•
Heavy use of regulator
•
Insufficient use of the cylinder drain cocks
Priming caused by high water levels, blowing off at the
safety valves, heavy use of the regulator or insufficient use
of the cylinder drain cocks, can be prevented by Enginemen.
When priming occurs, the regulator should be eased and the
cylinder drain cocks opened. The scum cock should also be
opened as this causes water to be drawn away from the
regulator valve.
If the water level is too high, the boiler may need to be blown
down.
If dirty water is evident, the scum cock can be used to clean
the surface scum off the boiler water.
Washing it out can rectify a dirty boiler. Frequent blowing
down of the boiler and frequent use of the scum cock can
lessen the build up of deposits on the boilerplate surfaces.
When an engine is being prepared at Box Flat Depot, the
boiler should be filled and then blown down using both the
blow down and scum cocks until the water level is reduced
to about 25mm.
The boiler should then be refilled to about three quarters of a
glass. When filling the boiler, the water valve on the injector
should be no more than one third open to allow slow filling of
the boiler. This will prevent rapid cooling of the boiler.
When standing for any length of time, the cylinder drain
cocks are to be opened. When starting the engine, the drain
cocks are to be kept opened until there is no sign of
condensed water being emitted from the drain cocks.
If the boiler is showing tendencies to prime when working
hard up a grade, opening of the cylinder drain cocks for a
few seconds at regular intervals may assist in preventing
priming.