Liquid product pipelines must be protected from liquid surges. Surges are caused by pump failure, rapid block valve closing, non-return check valve hard-shutting, emergency shutdown of a tank or loading system, or even a pump coming on or tripping. The magnitude of surge pressures varies, some virtually undetectable to those severe enough to cause significant damage. These propagating waves, either increasing or decreasing rapidly, are commonly known as a transient hydraulic surge of water hammer that can cause severe damage to liquid product pipelines, vessels, flanges, valving, and associated equipment.
The Flow Safe SurgeFlow series has been developed exclusively for liquid surge protection. These valves are extremely simple and 100% reliable. The dome cavity volume on top of the main valve piston is filled with nitrogen gas to affect the valve's proper set pressure. Dome gas pressure is set according to the characteristic piston seat-to-seal area ratio for the given valve size. This dome load forces the main valve into a closed position using a soft elastomer seat, providing a 100% tight shut-off. When surge pressure is sensed, the SurgeFlow valve piston opens immediately as the liquid fluid force acting under the piston overcomes the force from the dome gas working on the top. The piston continues to lift in proportion to the pressure surge, slightly compressing the dome gas. The closing cycle responds directly to pressure decay in the piping upstream of the SurgeFlow surge relief valve.
SurgeFlow series valves are designed for accurate and repeatable performance. They will handle both minimum and maximum surge cases when called upon to relieve. Flow Safe suggests all surge relief valves be located nearest the point where maximum pressure can occur in the main pipeline for optimal safety purposes.
For more information about Flow Safe products in New England, contact Piping Specialties. Call them at 800-223-1468, or visit their website at https://psi-team.com.
