Even though a valve is properly sized for a predetermined rate of flow, a dangerous condition may occur if capacity is restricted or the valve malfunctions. A Safety Head at the valve outlet isolates working parts from external corrosion. With the assurance of clean valve internals when rupture disk actuates, the valve should sense overpressure and operate within acceptable tolerances of set point. Less expensive valve trim material can be used. Valves last longer, require less maintenance, and reduce downtime.
Pressure is injected between disk and valve inlet.
When Safety Head is installed at valve inlet, a tricock, pressure gauge or some type of tell-tale indicator should be inserted between the disk and valve inlet. When a Safety Head-Valve combination is used with Safety Head at valve inlet and product to be discharged is corrosive, viscous, or of a formula that could affect performance of the valve, it is recommended the valve and Safety Head flange assembly be cleaned thoroughly before installing a replacement rupture disk. This method of testing relief valves is covered by U.S. Patent No. Check pressure rating on disk tab before injecting pressure for valve testing. When valve reseats, it may not be tight.