Pilot-Operated Safety Relief Valve

The 3900 series pilot-operated safety relief valve is designed for use in a wide range of applications requiring the discharge of liquid, gas, and steam.

Pilot-operated safety relief valves are used in various industries for working with liquid and gaseous fluids, meeting the most stringent technological requirements. With high performance demands, a single pilot-operated valve can replace multiple spring-loaded safety valves, significantly reducing project costs. Pilot-operated safety relief valve consists of a main valve and a pilot valve. The pilot valve, reacting to changes and using the pressure in the system, controls the force acting on the upper surface of the main valve's spool, thereby ensuring a tight seal in the closed position until the system pressure exceeds the set pressure.

When the set pressure is exceeded, the pilot valve relieves the pressure on the upper surface of the main valve spool, thus allowing the main valve to open. When the pressure in the system falls below the set pressure, the pilot valve ensures that it acts on the upper surface of the spool of the main valve, thereby providing the tight closure of the latter.

Pop action, characterized by rapid and complete spool movement when the set pressure is exceeded.
Modulating action, characterized by gradual spool movement proportional to the increase in pressure above the set point

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Type pilot-operated
Nominal diameter Inlet DN 25…300 mm Outlet 50…400 mm
Nominal pressure Inlet ANSI class 150 to 2500 (PN 2,0 ÷ 42 MPa) Outlet ANSI class 150 to 300 (PN 2,0 ÷ 5,0 MPa)
Operating temperature - 40 to 263 °C
Set pressure 0,1 to 25,8 MPa
Flow area 21 sizes from 0,71 to 451,22 cm²

Technical specifications

Type pilot-operated
Nominal diameter Inlet DN 25…300 mm Outlet 50…400 mm
Nominal pressure Inlet ANSI class 150 to 2500 (PN 2,0 ÷ 42 MPa) Outlet ANSI class 150 to 300 (PN 2,0 ÷ 5,0 MPa)
Operating temperature - 40 to 263 °C
Set pressure 0,1 to 25,8 MPa
Flow area 21 sizes from 0,71 to 451,22 cm²
Material of construction carbon steel / stainless steel / cold-resistant carbon steel / special steels and alloys
Leakage test API 527
Type of connection flanged

Execution options

With a lifting lever

Cap with a test gag

With soft seat

For hydrogen sulfide service

Design for liquid and gaseous media

With a lifting lever

Packed or open lifting lever

Cap with a test gag

With a test gag to hold the safety relief valve closed during hydrostatic test

With soft seat

Soft seat design (seat tightness at an operating pressure equal to 95% of the set pressure)

For hydrogen sulfide service

In accordance with the requirements of the NACE MR 0103/01-75 standard for media containing hydrogen sulfide

Design for liquid and gaseous media

Pop action (for gaseous media) / modulating action (for liquid media)

Features

Trim made of stainless steel

Trim made of stainless steel in standard design
No backpressure

The valve is not affected by backpressure
Portable device

Portable pilot valve testing device

Remote sensing

Remote sensing
Filters on the pilot tube

Filters on the pilot tube for purifying of the working fluid