series 440

Series 440 Pilot-Operated Safety Valve – Modulating Action

The Series 440 is a pilot-operated safety valve designed for modulating operation. The pilot regulates the pressure acting on the main valve, allowing the main valve disc to open and close gradually as a function of system pressure. The degree of opening varies with pressure in a proportional, but not necessarily linear, relationship.

Unlike pop-action operation, modulating action allows the main valve to operate at intermediate opening positions in response to changing pressure conditions. This enables the valve opening to adjust progressively to the prevailing relieving demand, subject to the valve’s design and performance characteristics.

The Series 440 is intended primarily for the liquid-service applications specified for this product. Suitability for a particular service must be verified against the fluid properties, operating conditions, required relieving capacity, back pressure, and the valve’s documented performance limits.

For applicable flanged-steel configurations designed in accordance with API 526, standardized inlet and outlet sizes, pressure ratings, and orifice designations are available. Final valve selection and orifice sizing must be based on the required relieving capacity and the specified process conditions.

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