Disclosed is a self-cleaning double block and bleed valve. The valve includes a plug modified to divert a portion of the fluid flowing through the valve into and through a cavity located beneath the plug. The diverted fluid passing along a secondary flow path beneath the plug and subsequently rejoining the primary flow path. The diverted fluid removes debris, sediment or sludge from the cavity beneath the plug.

A plug member of a gas valve, having an axial bore, a first bore and a second bore located in a radial direction thereof to respectively communicate with the axial bore, and a first guiding slot and a second guiding slot recessed into an outer peripheral surface thereof. The first bore is larger than the second bore, and communicates with one end of the first guiding slot, while another end thereof is near the second bore. The first guiding slot becomes narrower from the first end to the second end. The second guiding slot has one end communicating with the second bore, and another end located between said first end and said second end.

A method of calibrating a choke system includes connecting to the positioner an electronic controller which is programmed to output a control signal representing the desired position of the plug, connecting to the electronic controller a flowmeter which is configured to provide a flow signal representing the rate of flow of fluid from the pump to the inlet and a pressure sensor which is configured to provide a pressure signal representing the fluid pressure at the inlet, connecting the inlet to a reservoir of fluid via a pump which is operable to pump fluid from the reservoir into the inlet at varying flow rates, and using gain scheduling to determine optimum values of proportional gain and integral gain required for control of the choke using a proportional differential and integral controller at a plurality of different rates of flow of fluid along the central flow passage.

Provided is a tandem cone valve capable of avoiding or reducing resistance on a valve switch caused by fluid pressure in a pipeline in the opening or closing stage. The cone valve includes valve rods, valve cores and a valve body. The valve cores include a first valve core and a second valve core. The first valve core and the second valve core are coaxially arranged in a valve core cavity. The outer walls of the valve cores are in the shape of cones; the first valve core and the second valve core are stacked one on the other, the first valve core is provided with a first valve core first flow hole and a first valve core second flow hole which penetrate through the inner wall and the outer wall of the first valve core, and the valve core cavity is provided with a valve core cavity flow hole corresponding to the first valve core first flow hole and the first valve core second flow hole. The cone valve is provided with the second valve core stacked coaxially on the base of the first valve core, and the second valve rod driving the second valve core to rotate is arranged in the first valve rod in a sleeved manner, thus the valve is simple and compact in structure; and the two levels of valve cores can each rotate to open/close the valve level by level, thus reducing momentary resistance when opening and closing a large cone valve.

A self-compensated sealed rotary cone valve core, comprising a valve sleeve, wherein an upper part of the valve sleeve is provided with an axial through hole; a lower chamber of the valve sleeve is provided with a conical surface coaxial with the axial through hole; an inlet cavity is formed in the cone platform; a through hole communicated with a water outlet in a side wall of the lower part of the valve sleeve is formed in a side wall of the inlet cavity; a screw rod part of the core shaft penetrating through the valve sleeve is sequentially sleeved by a limiting piece and a spring gasket and is locked by a screw nut to realize pre-tightening sealing and rotary positioning with the valve sleeve. The valve core is simple in structure and convenient to process and mount, self-sealing and wear self-compensation can be achieved.

A floating ball valve comprising: a housing having an internal cavity and first and second fluid flow ports through which fluid flows selectively in either direction from the first to the second or the second to the first fluid flow ports when the valve is open; a floating ball housed in the cavity and formed having a through hole for passage of fluid the ball being rotatable to open the valve and allow fluid flow through the fluid flow ports and internal cavity and to close the valve and block fluid flow through the fluid flow ports and cavity; and a pressure relief valve (PRV) having a cracking pressure mounted to the floating ball so that the PRV communicates with the through hole, and when the floating ball valve is closed the PRV faces and communicates with the first fluid flow port; wherein the PRV is normally closed whether the floating ball valve is open or closed, and when the floating ball valve is closed, if pressure in the internal cavity exceeds the cracking pressure of the PRV, the PRV opens to relieve the pressure.

A stopcock for a liquid channel of a medical endoscope, having a housing, a spring element and a plug rotatably mounted in the housing, wherein the plug in a working position lies with its conical surface against a seal surface of the housing and can be placed in a medium access position in which the conical and the seal surface have no contact and the housing and the plug remain connected, characterized in that the plug includes one or more transverse grooves, in the outer wall of a conical piece, running transversely to the longitudinal axis of the conical piece and having straight groove bottoms, and the spring element in the medium access position engages with one or more transverse grooves. A medical endoscope having at least one liquid channel, characterized in that it includes at least one stopcock, by which the liquid flow through the channel can be regulated.

A self-compensated sealed rotary cone valve core, comprising a valve sleeve, wherein an upper part of the valve sleeve is provided with an axial through hole; a lower chamber of the valve sleeve is provided with a conical surface coaxial with the axial through hole; an inlet cavity is formed in the cone platform; a through hole communicated with a water outlet in a side wall of the lower part of the valve sleeve is formed in a side wall of the inlet cavity; a screw rod part of the core shaft penetrating through the valve sleeve is sequentially sleeved by a limiting piece and a spring gasket and is locked by a screw nut to realize pre-tightening sealing and rotary positioning with the valve sleeve. The valve core is simple in structure and convenient to process and mount, self-sealing and wear self-compensation can be achieved.

A disposable dental valve device is disclosed having a valve body having an interior, a tip receiving end for receiving a tip, a socket hose receiving end for receiving a tube having a beaded end, a lumen formed between the tip receiving end and the socket hose receiving end, and a partial opening formed in the valve body, a rotatable valve sealing body adapted to be inserted into the partial opening, and the rotatable valve sealing body having a bore for alignment with the lumen formed between the tip receiving end and the socket hose receiving end.

Provided is a tandem cone valve capable of avoiding or reducing resistance on a valve switch caused by fluid pressure in a pipeline in the opening or closing stage. The cone valve includes valve rods, valve cores and a valve body. The valve cores include a first valve core and a second valve core. The first valve core and the second valve core are coaxially arranged in a valve core cavity. The outer walls of the valve cores are in the shape of cones; the first valve core and the second valve core are stacked one on the other, the first valve core is provided with a first valve core first flow hole and a first valve core second flow hole which penetrate through the inner wall and the outer wall of the first valve core, and the valve core cavity is provided with a valve core cavity flow hole corresponding to the first valve core first flow hole and the first valve core second flow hole. The cone valve is provided with the second valve core stacked coaxially on the base of the first valve core, and the second valve rod driving the second valve core to rotate is arranged in the first valve rod in a sleeved manner, thus the valve is simple and compact in structure; and the two levels of valve cores can each rotate to open/close the valve level by level, thus reducing momentary resistance when opening and closing a large cone valve.