Industrial Valves

HOW TO CONSIDER RELIEF SYSTEM ?????  The entire relief system must be considered before selecting the appropriate relief device. The relief headers should be designed to minimize pressure drop, thus allowing for future expansion and additional relief loads. Conventional spring-loaded-relief-valve considerations. Conventional valves require the relief header backpressure (superimposed plus built up) to be less than 10% of the set pressure of the lowest-set relief valve tied into the header. Balanced-spring-loaded-valve considerations. Balanced spring-loaded valves allow the use of smaller relief headers because of the larger pressure drops allowed, under maximum relief-flow conditions, as a result of higher allowable backpressure (40%). Balanced valves and relief headers are designed as a system to operate at a higher backpressure. The balanced valve is more expensive than conventional valves; however, the total cost of the use of balanced valves plus the smaller header sy...