No fewer parts can be used in a pump
required to lift water and force it against steam pressure. More check
valves may be used, but it would not do to use less. Each has its work
to do, and the failure of one defeats all the others. The pump barrel
is a hollow cylinder, the chamber being large enough to admit the
plunger which varies in size from 5/8 of an inch to I inch in diameter,
depending upon the size of the boiler to be supplied. The barrel is
usually a few inches longer than the stroke of the engine, and is
provided at the cross head end with a stuffing box and nut. At the
discharge end it is tapped out to admit of piping to conduct water from
the pump. At the same end and at the extreme end of the travel of the
plunger it is tapped for a second pipe through which the water from the
supply reaches the pump barrel. The plunger is usually made of steel and
turned down to fit snug in the chamber, and is long enough to play the
full stroke of engine between the stuffing box and point of supply and
to connect with the driver on the cross head.
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