US Patent 6837403 High pressure rotary valve with sound reduction means

A rotary valve generally consisting of a housing having a cylindrical chamber provided with an inlet communicable with a zone of a first pressure, a first outlet communicable with a zone of a second pressure greater than said first pressure and a second outlet communicating with the exterior of said housing, a shaft journaled in the housing extending through and disposed coaxially relative to the axis of the chamber, a rotor mounted on the shaft within the chamber, between the inlet and each of the first and second outlets, having at least one set of circumferentially spaced material receiving pockets communicable sequentially with the inlet and the first outlet and the second outlet for receiving material through the inlet and discharging the material through the first outlet, and a device intercommunicating the second outlet and the exterior of the housing for diffusing the flow of gas vented from the rotor pockets through the second outlet to exterior of the housing to muffle the sound of venting gas.