Milton Roy Dosing Pump GB404

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

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

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 all shut-off valves are closed and all pressure has been bled from liquid end.

Drain oil from the pump by unscrewing the drain plug (20) and O-Ring (19).

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 (261) is fully forward, and unscrew the diaphragm from the connecting rod (60).

Pre-Replacement Safety Measures

Ensure shut-off valves are closed

Inspection of Check Valve Components

Inspect ball check for chemical or physical damage

Inspect seat for sharp edge and damage

Replacement of Check Valve Components

Systematically change O-Rings and/or gaskets during valve replacement