Liquid Controls MA4 Meter - Manual (Page 17)

17
Differential Valve Maintenance
Faulty operation of the differential valve may be caused
by defective valve seals, the spring, or the diaphragm.
The diaphragm and the O-Ring valve seat are the only
parts that should require replacement in normal service.
It is not necessary to remove the valve from the line for
disassembly.
Disassembling the Valve
1. Remove connecting tube between differential valve
and vapor eliminator cover. See illustration on Page
15.
2. Unscrew the union nut and remove the spring case,
limit stop, and spring from the body.
3. Remove the diaphragm and piston assembly.
4. The diaphragm can be inspected by unscrewing the
nut and removing the diaphragm head.
5. Inspect the diaphragm for cuts, tears, or pinhole
leaks. Replace if defective. Caution: Do not over
tighten diaphragm retaining nut. Torque
diaphragm retaining nut to 18-20 inch-lbs.
6. Check the O-Ring and replace if necessary.
7. Reinstall piston assembly into body, insert spring,
limit stop, spring case and union nut.
8. Reassemble connecting tube.