Pump Function; Double Acting Pump - Nordson ProBlue Flex Product Manual

SP Pump Diagnostics and Repair
B-2

Pump Function

Double Acting Pump

Part 1128350_02
The ProBlue Flex adhesive melters may have either a double acting or a
single acting piston pump.
The double acting pump discharges material during both the upward and
downward stroke of the piston.
The pump consists of an air section and a hydraulic section. Air is supplied to
the pump through an air filter and a regulator. From the regulator, air flows to
an air valve inside the air section. The air valve directs air into either the
upper or lower portion of the air cylinder, which forces the piston assembly up
or down. The lower end of the piston assembly contains a pressure ball
valve. At the bottom of the hydraulic section is a siphon ball valve.
When the air valve directs the stroke of the piston upwards, the piston
creates suction within the pump body, which opens the siphon ball valve and
closes the pressure ball valve. As the piston moves upwards, material is
simultaneously drawn into the pump below the pressure ball valve and forced
out of the pump chamber above the pressure ball valve. Material leaving the
pump chamber passes through a filter and then into a manifold, where it is
distributed to the hoses/applicators.
Attached to the piston assembly is a shifter fork. The fork travels along the
shaft of the actuator assembly that has a magnet at both ends. When the
stroke of the piston carries the shifter fork upwards, a magnet in the shifter
fork attracts the magnet at the end of the actuator, which shifts the position of
the air valve. When the valve shifts, air is redirected to the opposite side of
the air cylinder, which forces the piston downwards.
On the piston downward stroke, material pressure below the piston closes
the siphon ball valve and opens the pressure ball valve. As the piston moves
downwards, material below the pressure ball valve is displaced, and forced
through the pressure ball valve and out of the pump chamber, where again, it
passes through the filter and into the manifold.
E 2020 Nordson Corporation