Abstract: A rotary control valve with a variable area orifice (or orifices) which communicate with a bypass channel in order to provide infinite control of flow across the valve. The bypass channel may contain a silencing means. This arrangement allows for in-line maintenance of, or modification to, either the silencing means or the valve body itself through top entry of the valve. The cross-sectional void area of the bypass channel may be sized to be the same as the cross-sectional area of the upstream and downstream valve ports in order to provide silencing without throttling the flow through the valve.

Abstract: A rotary control valve is provided with a variable area orifice in the control element that communicates with a bypass channel, which contains noise silencing means, when the valve is in the less than full-open position. This arrangement minimizes cavitation and noise when the valve is not in the full-open position while providing maximum flow with minimum friction and pressure drop when the valve is in the full-open position. The removable bypass channel configured with a single variable orifice in the control element allows for in-line maintenance of, or modification to, either the noise silencing means in the removable bypass channel or the valve body itself through top entry to the valve. The cross-sectional void area of the upstream and downstream ports as a means of further reducing noise and controlling velocities. The silencing means located within the bypass channel can be a multiplicity of balls or other such means that can be placed within the bypass channel.

Abstract: In the preferred and illustrated embodiment found in the drawings herein, tool retaining apparatus is disclosed. It is a catch mechanism for catching and securing wireline tools. It incorporates an elongate tubular body to be attached at the well head and works above a producing well. It is axially hollow to pass a wireline supporting a down hole tool. The elongate tubular body surrounds a sleeve positioned within it. The sleeve has a shoulder around its exterior to define upper and lower pressure receiving chambers, thereby enabling external pressure to be applied to drive the sleeve up or down. The sleeve supports a pair of opposing pivotally mounted flaps at the top end. The flaps have laterally projecting tabs which are positioned in cavities to enable the flaps to extend toward one another. They are supported on a shoulder to maintain a catch position. Because they are pivotally mounted, a wireline supported down hole tool can be retrieved upwardly through or past the flaps.