series 840

Series 840 Safety Valve – Balanced Bellows Type

The Series 840 is a spring-loaded safety valve incorporating a balanced bellows designed to minimize the influence of outlet back pressure on set pressure and operating characteristics. This configuration is suitable for applications involving variable back pressure or discharge into a common relief header, provided that the valve’s specified operating limits are respected.

Depending on the valve construction, the bellows may also isolate the bonnet and spring area from direct contact with the process fluid. The suitability of the bellows material and its operating limits must be verified for the intended process conditions. A balanced-bellows design reduces the influence of back pressure but does not eliminate the need to evaluate the discharge system and permitted back-pressure 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 should be based on the required relieving capacity, process-fluid properties, inlet and outlet conditions, and applicable design requirements.