Milton Roy Dosing Pump GB403

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

Refer to Figure 9 or 11 before starting disassembly

Unscrew the union nut (435) to separate the union end (445)

Unscrew the ball guide (424) from the liquid end

Screw the union nut part way onto the end of the ball guide with the seat

Place the ball guide/union nut onto a flat surface with the union nut down

Insert a thin, blunt instrument into the small center hole of the ball guide

Tap screwdriver gently with a hammer to release the ball and seat

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).

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

Unscrew the ball guide (424) from the liquid end

Remove and discard the O-Rings (419)

Carefully clean any parts to be reused

Do you suspect the check valve may be damaged or worn?

Replace the entire check valve assembly if damage or wear is suspected