Opening and closing of a valve always has a temporary dynamic effect on the pressure conditions within a control system. The level of the change in pressure amplitude depends to a large degree on these physical parameters: static system pressure, hydrostatic pressure, pipe diameter, temperature, mass of the medium and the opening and closing response of the valve. While much is known about the physical facts, the opening and closing response of a valve is a variable that can

hardly be calculated. However, the effects of excessive pressure amplitudes (pressure impacts) within a system can be serious. Noises and vibrating pipes are the most harmless effect. Pressure impacts can be as high as 36 times the rated pressure, resulting in damage to measurement hardware, pipes or shut-off valves. The required system availability can be increased by soft stop valves with a reduced pressure amplitude during closing. Bürkert takes this into account in the fluidic design of the internal valve construction.