Pilot Operated Pressure Reducing Valve Troubleshooting
| Symptom | Probable Cause | Remedy |
| Main valve won't open | No pressure at valve inlet | Check inlet pressure |
| Main valve diaphragm assembly inoperative | Disassemble, clean and polish stem, replace defective parts. | |
| Pilot valve (BR4) not opening: (1.) No spring compression, or (2.) Damaged spring. | (1.) Tighten adjusting screw. (2.) Disassemble and replace spring. | |
| Flow control disc inoperative. Corrosion or excessive scale buildup on stem. | Disassemble, clean and polish stem, replace defective parts. | |
| Main valve fails to close | Foreign matter between disc and seat or worn disc. Scale on stem or diaphragm ruptured. Flow clean strainer plugged or isolation valves closed. | Disassemble main valve, remove matter, clean parts, and replace defective parts. Remove and clean or replace strainer. Open isolation valves. |
| Pilot valve (BR4) remains open: | ||
| 1. Spring compressed solid | 1. Back off adjusting screw | |
| 2. Mechanical obstruction | 2. Disassemble and remove obstruction | |
| 3. Worn seal ring | 3. Disassemble remove and replace cartridge assembly | |
| Fails to regulate | Air in main valve cover and/or tubing | Loosen top cover plug and fittings and bleed air. |
Click below for installation and maintenance sheets:
ZW109
Installation and Maintenance sheet
ZW109BP
Installation and Maintenance sheet