When the differential pressure is too high and drop in one step in gaseous fluid, sonic flow occurs so it may generate noise upper than limit of standard (85 dB). And in parallel, in liquid fluid when the differential pressure is too high and again drop in one step, flushing or cavitation occurs in downstream side. So it is required to design multi-stage restriction orifice. There are two types that depend on fluid condition: one is both end flanges and the other is to insert in piping. In high velocity fluid it is recommended to protect the up-stream surfaces of orifices by satellite. In inconvenient condition when it is necessary to decrease the noise, multihole restriction orifice recommended.
The assembly is complete with below items according to your request:
(1)- Two welding neck flanges, according to ANSI B16.5 standards.
(2)- The proper quantity of perforated plate. This quantity and the number of stage are specified after flow calculations.
(3)- The proper quantity of pipe pieces.