Milton Roy Dosing Pump GB403A

Separate the following components

Remove and discard the three gaskets (419)

Carefully clean any parts to be reused

Ensure all shut-off valves are closed

Bleed all pressure from the liquid end

Disassembly (Refer to Figures 7 and 8)

Set the stroke adjusting knob to 100%

Disconnect the suction and discharge piping

Unscrew the six diaphragm head bolts

Remove the diaphragm head assembly from the pump body

Turn the motor fan by hand until the end of the diaphragm assembly is fully forward

Drop the ball into the curved inner chamber end of the ball guide.

Place a new gasket on the rim of the ball guide, and sit the seat on top of the ball guide, trapping the ball and gasket between the seat and ball guide.

Position the connection (435) onto the correct end of the ball guide with a gasket trapped between the two metal surfaces.

Position the check valve assembly onto the liquid end, trapping a gasket between the two metal surfaces. (Seat and pump head).

Slide the valve clamp (437) over the connection (435) and screw into the liquid end using the three screws (441,442) and their split washers (439).

Fit new O-Rings into position on the ball guide and seat

Drop the ball into the curved inner chamber end of the ball guide

Sit the ball guide on a flat surface with the ball facing upwards

Position seat on the ball guide, trapping the ball inside

Press the seat into the ball guide with firm, even pressure ensuring the beveled edge faces outward

Position the union end onto the correct end of the ball guide

Ensure the correct end of the check valve assembly is screwed into the liquid end

Trap a new O-Ring between the liquid end and the check valve assembly

Use new O-Rings for each reassembly to ensure a tight, leak-free seal

Refer to Figure 10 for proper assembly order of suction and discharge check valves

Verify the check valve cartridges are installed correctly to prevent damage or malfunction

Screw the coupling (445) onto the check valve assembly

Trap a new O-ring (419, 423) between the coupling and the check valve assembly