Milton Roy Dosing Pump GB401

Unscrew the ball guide (424) from the liquid end

Remove and discard the O-Rings (419)

Carefully clean any parts to be reused

Is the check valve suspected to be damaged or worn?

Replace the entire check valve assembly if damaged or worn

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

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

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).

Screw the correct end of the check valve assembly into the liquid end

Screw the coupling (445) onto the check valve assembly

Are all O-Rings new and properly installed?

Is the assembly free from leaks after reassembly?