The usefulness of valves for operation in the conditions of large drops in pressure depends on the structure of the internal elements of the valve.

The parameter that is decisive for the admissible critical drops in pressure in the conditions of throttled flow or cavitation, is the FL pressure recovery 

∆p = K∙FL2(p1-pv)

where:

K=0.85 - for throttled flow,

K=0.67 - for cavitation

The value of the FL pressure recovery index may change in the range between 0.5 and 1.0, depending on the type of the valve. The valves with high pressure recovery (throttling valves, ball valves) have a low value of the FL index and little usefulness for operation in the conditions of throttled flow or cavitation.

For those applications, the construction of the valve should guarantee the achievement of maximum FL coefficient values.

Those requirements are met by the Z1B-M valves with labyrinthine multi-track direction of the stream flow in the valve throttling elements (FL = ~0.975).

In a set of throttling cages, there are the elements that ensure the division and breakdown of the stream with preservation of the gradual increase in the flow field.

Plant, and meets the process requirements without reservations.

The Z1B-M valves are dedicated to liquid and gas media, and the number of their applications in power engineering and gas engineering confirms the high assessment of their usefulness in the most difficult working conditions.