The Zurn Wilkins Model ZW205 Pilot Operated Pressure Relief / Pressure Sustaining Valve is designed for applications where it is critical to maintain a pre-determined upstream pressure. The pilot assembly reacts to changes in upstream pressure allowing the main valve to modulate between the closed and open position, maintaining desired upstream set pressure. As long as the upstream pressure is below the set point of the pilot assembly, the main valve will stay in the closed position (sustaining); however, once the upstream pressure exceeds the set point of the pilot assembly, the main valve will open and relieve the excess pressure (relief).

The Model ZW205 pilot system is designed to sense upstream pressure. The pilot piping contains a normally closed, direct acting, spring loaded pilot valve, which may be preset to the particular pressure requirements of the system (Pilots are available in pressure ranges from 0 to 300 psi.). If upstream pressure does not exceed the preset on the pilot spring, the pilot and the main valve remain tightly closed. Should upstream pressure exceed the set point of the pilot, both the pilot and main valve will open, relieving the excess pressure by allowing flow through the valve. When upstream pressure returns to acceptable limits, the reverse action occurs. An adjustable flow control valve in the pilot piping provides quick opening for pressure relief and slow closing for surge protection.

• Serves as either a relief or sustaining valve.
• Pressure gauge, wye strainer, isolation valves, and epoxy coating come standard to simplify start-up and maintenance.
• Standard relief range is 50 to 200 psi, other ranges available.
• Globe, reduced port globe, and angle bodies available.
• 150 class flanged, 300 class flanged, grooved, and threaded end connections available for installation versatility.