Keeping forces in check: LESER Dual Outlet POSV

The new Dual Outlet POSV is an important step towards completing the LESER portfolio of pilot-operated safety valves (POSV).

When a safety valve opens, the impulse of the exiting media exerts a force that pushes the valve into the direction opposite the outlet. This force, called reaction power, is calculated when a safety valve is sized, for example according to the API 520-2 or AD 2000 data sheet. The rule of thumb is: The higher the mass flow and the larger the surfaces, the stronger the resulting reaction power. To prevent this force from transferring through the connected pipeline and causing damage, it must be absorbed by steel structures and foundations.

The new Dual Outlet POSV by LESER represents a smart solution that avoids complex support structures. Two opposing outlets split the flow equally, which causes the two sides’ reaction powers to offset each other.

A key application for this valve type is compressor stations on natural gas pipelines. Since they aren’t typically part of some major industrial plant, the reaction power cannot be absorbed by structures in the immediate vicinity.

The safety valves used have nominal sizes up to NPS 8 x 10 x 10 and set pressures up to 100 bar-g. According to API 520-2, the reaction power generated on a single-outlet POSV in such an application can be as high as 370 kN.