The surge anticipation valve is a pilot operated plug valve. When there is a sudden drop in pressure (associated with a pump failure), the valve automatically opens rapidly, and then closes gradually. The time for opening and closure is configurable by the designers.
The philosophy of the valve’s operation is to ensure there is discharge to atmosphere when recoil pressures are at a maximum.
In reality it has very limited potential application. For the majority of pumping rising mains, the recoil pressure is less than the steady state pressure in the pipeline. The surge damage in these lines is more likely to be a result of negative pressures some way down the pipeline. This valve will not address these negative pressures, and may in fact exacerbate them.
The valve also has the effect of partially depriming the pipeline. This can result is severe pressures occuring at deprimed sections on pump restart.
The device can be effective in some circumstances in which the recoil is of prime concern. It is essential that the designer is aware of the valves limitations and considers the potential risks. Safe surge protection using these valves would require detailed computer modelling of all significant transient events including those that could be induced by the valve.