Honda WDP30X Owner's Manual page 22

OPERATION
When water being pumped contains solids, the solids may get lodged
under the clappet valves which will prevent the clappet valves from
closing completely. To maintain maximum pump performance, the
discharge hose should angle upward as it exits the pump.
DISCHARGE
HOSE
If the discharge hose must run
across a roadway, the hose
should cross the roadway
perpendicular to traffic flow. Also,
heavy boards should be placed
next to the hose so the
motor-vehicle weight does not
shut off the discharge as vehicles
cross over the hose. Driving over
a discharge hose while the pump
is running or even possibly when
the pump is stopped will most
likely cause pump case failure.
Collapsing the discharge hose will cause pump case and/or
diaphragm damage. To prevent pump damage, take the necessary
precautions to prevent the discharge hose from getting compressed
or collapsed.
During freezing weather, always drain the pump case after use. If
water is left in the pump case during freezing weather, the pump case
will break.
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