Universal Pump Service Manual
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2. A ach the fi lter housing inlet (Figure 1, #9) to the outlet of the magnehelic gauge. Ensure magnehelic gauge reads
minimum back pressure.
3. Turn on the pump and adjust the fl ow adjust pot on the pump (Figure 1, #7) until the dual-ball rotameter reads
1500 ml.
4. Using a fl at-head screwdriver, turn the regulator shut-off screw (Figure 1, #16) counterclockwise four or fi ve turns.
This will open the regulator isolation valve and allow it to work.
5. With the regulator isolation valve open, close off the inlet to the dual-ball rotameter.
6. If the magnehelic gauge reads 20 inches back pressure, no adjustment is needed. If the gauge reads over or under
20 inches, slowly adjust the regulator adjustment screw (Figure 1, #14) until the magnehelic gauge reads 20 inches.
Turn the regulator adjustment screw clockwise to increase pressure and counterclockwise to decrease pressure.
If you exceed 20 inches while turning the regulator adjustment screw, release block on the dual-ball rotameter
inlet, turn the regulator adjustment screw counterclockwise, close off inlet to dual-ball rotameter, and slowly turn
the regulator adjustment screw until the gauge reads 20 inches.
To double-check adjustment, release block on rotameter inlet, then reapply. The gauge should still read 20 inches.
7. When the pump is set at 20 inches back pressure, reinsert the cap screw, and release all back pressure. The pump
is now set for low fl ow operation between 5 and 500 ml/min. To return the pump to high fl ow operation, turn the
regulator shut-off screw (Figure 1, #16) clockwise until it is in the closed (down) position. Replace the cap screw.
Disassembling the Stack
1. Remove the two cap screws from the top of the pump (Figure 1, #15 and 16).
2. Carefully li! the stack and fi lter housing assembly straight up and lay on top of the control board to the right or
onto a surface to the le! of the pump. Remove the brown plate from the top of the pump.
Wires attach the stack to the control board. Avoid excessive strain on wires.
3. Remove the short black tubing on the fl owmeter from the stack (regulator) inlet and pull the fl owmeter away from
the pump (the fi lter housing assembly will come away with it).
4. Remove the top half of the stack by loosening the screw beside the exhaust port and the screw beside the regulator
isolation valve on top of the stack (Figure 2, #1 and 11). The stack will fall into two halves. The top half stack
contains the regulator and pulsation dampener assemblies. The bo om half stack contains the valve, yoke/
diaphragm, and motor assemblies.
Leave the two long screws loosened, but in place in the top half stack. This will help to hold all the components of the top
half stack together. Also note the position of O-rings. Ensure that they do not drop out of place during troubleshooting.
5. Using a small Allen wrench, loosen the set screw on each side of the pump housing in the bo om half stack
(Figure 8, #14).
6. Gently remove the motor assembly by gripping it with suitable pliers and slowly twisting it while withdrawing it
from the pump housing.
When removing the motor, be careful with the pliers. Do not let them slip and damage the
motor. Do not pull the wires soldered onto the motor.
7. Remove the fi ve screws on the bo om valve plate (Figure 2, #6 and 5).
One screw is shorter than the rest and must be replaced in the same hole from which it was removed so that the motor
is not damaged. Keep this screw and its counterpart from the top valve plate separate from the rest of the screws
(Figure 2, #13).
