I am washing out the middle left hand side of the boiler. The casing with the red-handle is the fire-mans side clack valve housing for the injector. The dome on the left is where the Regulator and manifold pipe is housed and so this is also given a spray with the bent nozzle. This gets rid of any sediment that could have built up around the regulator and will stop it from possibly being carried over with the steam into the cylinders.
Credit: Chris Perkins, 16 April 2005