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Reference information
32
Pump P-960
User Manual 18-1172-73 Edition AA
6.3
Liquid delivery
Pump P-960 has one inlet port and one outlet port. In the connection
part, the inlet flow path as well as the outlet flow path are split into
three separate flow paths – one to each plunger pump chamber. All six
flow paths are equipped with non-return check valves.
Fig 6-1.
Cross section of the flow path in the connection part
Consequently, each one of the three plunger pump chambers has one
inlet and one outlet. Liquid is drawn up into the chamber through a
check valve by the pump plunger being withdrawn from the chamber.
On the delivery stroke of the plunger, the inlet check valve is sealed by
the pressure developed and liquid is forced out through a similar check
valve in the outlet flow path.
After exiting the connection part through the pump outlet, the flow
passes the pressure sensor where the pressure is measured.
The three plunger pumps are actuated by pistons in a sequential order,
meaning that the pump phases are displaced by 120°. The sequential
pumping action of the pistons is provided by a rotating stepper motor
assembly through an axial bearing. The bearing is slightly inclined,
which results in a sequential motion of the plunger pumps, and hence a
smooth and continuous liquid delivery.
The stepper motor has automatic speed control to reduce pulsation.
The pump is also equipped with pressure compensation.
Leakage between the connection part and the pump chambers is
prevented by O-rings. Any leakage behind the plungers is diverted
through the drainage hole in the front of the connection part. The check
valves are also equipped with O-rings.
Outlet port
Inlet port
Plunger pump
chamber (x3)
Leakage hole
Optional outlet
port
Check valve
(x6)
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