_a._ For this, alternately shut down the main outlet gate and adjust
the hand-wheel of the safety valve, and open up on the throttle as may
be required, running pump at say one-half speed (or, in experienced
hands, at full rated speed), and note the greatest water pressure which
the full boiler pressure (unless boiler pressure is above 85 lbs.) will
yield with pump at full speed.
Sometimes it may be necessary to force water through very long lines
of hose, or to an unusual height.
Steam fire engines are not infrequently called on to give 200 pounds
per square inch water pressure.
To test short hose lines with anywhere near so high a pump-pressure
is dangerous, lest nozzle kick and pull itself away from the man
holding it and thrash around; but the ability of the pump may be
tested by putting this high pressure-delivery mainly through the
safety valve, or in part through the partially closed main outlet
gate.
_It is not advisable to carry this water pressure above 200 pounds
in this test_ at the factory, (although in the shop test the water
pressure is carried to 240 pounds) and engine driver should stand
with his hand on the throttle.