Harbor Freight Tools 2" Gasoline Powered Clear Water Pump 68375 - Manual (Page 9)

Page 7 For Pump technical questions, please call 1-800-444-3353. Item 68375
For Engine technical questions, please call 1-800-520-0882.
Locating the Water Pump
Locate the Water Pump on a flat, level, sturdy surface
capable of supporting the weight of the Pump.
1. For best Pump performance, place the Pump near
the water level and use hoses that are no longer than
necessary. This will allow the Pump to produce the
greatest output with the least self-priming time. See
diagram below.
Total Head
Suction
Head
Water Pump
Discharge Head
As the head (pumping height) increases, pump
output decreases. The length, type, and size of the
suction and discharge hoses can also significantly
affect Pump output.
Discharge head capability is always greater than
suction head capability. This means pumping height
for the Intake Hose (suction head) should be shorter
than the pumping height for the Discharge Hose.
Minimizing suction head (placing the Pump
closer to the water level) will also help reduce
self-priming time. This is the time it takes the
Pump to bring the water from the water level
to the Pump during the initial operation.
2. Route the Intake Hose with the Intake Strainer
fully immersed in the water supply source.
3. Place Strainer into water to be pumped. CAUTION:
Strainer must be fully immersed in water.
Do not operate Pump without Strainer connected to
end of suction hose. Keep Strainer out of sand or
silt by placing Strainer in a bucket or on stones.
NOTICE: If there is an air leak in the suction
line, you may not be able to prime the pump.
Use of a thread sealant is recommended.
4.
Strainer
Secure the Intake Hose in place to keep it from moving
once the Pump is turned on. The Intake Hose should
be as short as possible for more efficient operation.
5. Route the discharge hose to the desired discharge
location. If necessary, connect additional discharge
hoses to direct the discharge to the desired location.
Make sure to secure the discharge hose in place
to keep it from moving once the Water Pump is
turned on. The discharge hose should be kept as
short as possible for more efficient operation.
Operation Concerns
1. Cavitation: This is the sudden formation and collapse
of low-pressure vapor (bubbles) across the vanes of
the impeller.
Cause: When the surface pressure on a liquid
becomes low enough, the liquid will begin to boil
(even at room temperature). With centrifugal pumps,
cavitation can occur when the suction vacuum
becomes too great, allowing water vapor or bubbles to
form at the impeller. The rapid pressure increase can
cause impeller damage.
Solution: Minimizing suction head and using
the largest practical suction hose diameter will
reduce the likelihood of cavitation. Do not use
a suction hose with a diameter smaller than
the Pump’s Intake Port (2″ diameter).
2. Water Hammer Pressure: This is energy sent back to
the Pump due to sudden stoppage of water flowing
from the Pump.
Cause: Water hammer pressure is more likely to
occur when using a very long discharge hose. If the
flow of water at the end of the discharge hose is shut
off suddenly, energy is sent back to the pump. This
causes a large pressure spike in the Pump housing,
leading to potential damage to the Pump casing.
Solution: Use as short a discharge hose as possible
and turn off water pump before closing water flow.