anderson greenwood pilot operated safety relief valve
anderson greenwood pilot operated safety relief valve

Specs & Brochures



Series 400 Modulating Safety Relief Valve

Pilot Operated Modulating Safety Relief Valve for Liq/Gas service Sizes: 1" thru 8" inlet Range: 15-1480 PSIG Temp: -65 to 600 F

The Series 400 modulating valve, with non-flowing pilot, incorporates an advanced design in pilot operated valves. Under process conditions, both pilot and main valve can be tight to as high as 98 percent of set pressure. The main valve lifts proportionally according to required flow, restricting product loss to only the mass required to be relieved to prevent process pressure from exceeding the code allowance.

The Series 400 valve is well suited for gas and/or liquid services, including dirty and/or wet services. The modulating action is strongly preferred for liquid relief because it minimizes the destructive effects of “liquid hammer.”

Features & Benefits:

  • Unique Field Test Capability: Allows accurate set pressure verification with valve in service. No system isolation valve or rupture disc required. All field test connections are provided with an indicator for accurate and easy set pressure testing.
  • Reduced Product Loss and Pollution: Soft seats for premium tightness before and after relief cycles. Modulating action relieves minimum product to prevent overpressur.
  • ASME Section VIII Code Stamp: Certified National Board capacities for both gas and liquid service assures user of independent third party flow rate verification.
  • Non-flowing Pilot: Minimizes entrance of dirt and formation of hydrates in pilot. Due to low velocities within the pilot and supply tubing, most particles will drop out upstream of pilot inlet screen. Optional cartridge type pilot filter is available for extremely dirty services.
  • Rugged Bracket Pilot Mounting: Extremely rigid mounting protecting against vibration and careless handling. Shake table proven.
  • Reduced Noise: Modulating action minimizes flow and resultant noise during normal system upset, reducing noise abatement costs.
  • Increased System Output: Because of valve tightness to 98 percent of set pressure, the system can be operated nearer set pressure without valve leakage, resulting in greater system throughput.
  • Reduced Maintenance Costs: Soft seats greatly extend service life, making costly and time-consuming metal seat lapping unnecessary.
  • Ease of Adjustment: Single adjustment for set pressure allows accurate and dependable setting.
  • Balanced Design: Proper valve operation and lift are unaffected by back pressure. Costly and fragile metal bellows are not required.
  • Minimal blowdown, as the valve reseats slightly below set pressure.
  • Remote sense option available at no added cost to the relief valve.

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