A. The safety valve controls the flow of oil from the fuel oil tank
through an opening in bottom sheet of tank to the pipes leading to
burner. This valve is forced to its seat by a heavy spring and is held
off its seat by a key in the upright rod extending above the top of
tank. To this key a rope or chain is attached and also attached to the
cab to cause the pin in rod to be pulled in case of a separation between
engine and tank and allow the valve to be seated by its spring and avoid
a waste of oil. The second or main oil valve is located in oil pipe
under deck leading to burner. It is usually of the plug-cock pattern
connected by bell crank and this connected to some part of the engine by
chain, in which case it also acts as a safety valve in case of
separation between engine and tender. In other cases it is connected by
an operating rod extending above deck of tender where it can be operated
by hand in case of safety valves failure to shut off the flow of oil.
The third or firing valve is usually located between heater box and
burner, and is provided with an upright rod extending into cab where it
is provided with a handle or lever in position to be conveniently
handled by fireman while seated in cab. This valve regulates the flow of
oil desired to reach the fire.