A check valve includes a housing defining a pair of valve openings, a pair of flappers pivotably mounted to a pin and such that they are configured to rotate relative to the housing between an open position in which they permit fluid flow through the valve openings and a closed position in which they prevent fluid flow through the valve openings, and an element configured to stop and hold the flappers in the open position. A cavity is formed between the pair of flappers and stop element when the flappers are in the open position. Each of the flappers comprise one or more contact surfaces configured to contact the stop element when in the open position. The stop element has stop surfaces with stationary contact areas configured to oppose and abut the flapper contact surfaces when the flappers are in the open position.

A valve housing for a check valve comprises a housing body defining a valve opening and a first pin extending across the valve opening defining a pin axis (A). The valve housing further comprises a pair of first pin support elements provided on the housing body on opposing sides of the valve opening and extending towards the first pin, the first pin support elements for contacting and supporting an under side of the first pin. The valve housing further comprises a pair of first pin location elements provided on the housing body on opposing sides of the valve opening, each first pin location element comprising a strip element having a mounting portion mounted to the housing body and a locating portion which extends over an upper side of the first pin and around at least an upper circumference thereof to locate the first pin.

A check valve comprising a valve body having a central bore a hinge pin a blocking means pivotably attached to the hinge pin and moveable between a first position in which the blocking means blocks the central bore and a second position in which the blocking means does not block the central bore, and a biasing means arranged to bias the blocking means into the first position, wherein the valve body comprises at least one boss projecting from an inner wall of the valve body into the central bore, and wherein said boss provides an anchoring point at which the hinge pin is secured to the valve body.

A check valve comprises a valve housing defining a pair of valve openings, a pair of flappers pivotably mounted for rotation relative to the housing between an open position in which they permit fluid flow through the respective valve openings and a closed position in which they prevent fluid flow through the valve openings, and a stop pin extending across the valve such that the flappers will contact the stop pin in their open positions. Each flapper comprises a primary flapper element and a secondary flapper element, each pivotally mounted to a hinge pin extending across the valve. The primary flapper element further comprises a flapper opening formed therethrough. The secondary flapper element is pivotally mounted to the hinge pin such that it may rotate relative to the primary flapper element for opening or closing the flapper opening.

A check valve includes a housing including a septum separating at least two openings formed therein, the openings being defined by an outer edge and one or more petals pivotably coupled together along the septum to occupy respective open and closed positions in accordance with a pressure differential of a fluid flow across the check valve. In this aspect, a cut height of the septum is greater than a cut height of at least a portion of the outer edge.

A check valve with a a housing having an inlet connected to an outlet. A stop and a membrane are disposed in the housing. The membrane is movable and bendable to control fluid flow between the inlet and the outlet. The stop may be an elongated extension about which the membrane may bend along a line or a curve such that the extension lies between overlapping sections of the membrane.

A check valve with a a housing having an inlet connected to an outlet. A stop and a membrane are disposed in the housing. The membrane is movable and bendable to control fluid flow between the inlet and the outlet. The stop may be an elongated extension about which the membrane may bend along a line or a curve such that the extension lies between overlapping sections of the membrane.

A flapper element for a check valve comprises at least one mounting lug configured to receive a shaft for rotation relative thereto and having a row of teeth for engaging complementary teeth on a mounting lug of a similar flapper element. The complementary teeth tie the rotation of the two flapper elements.

A vale unit includes a valve frame and two valve plates. The valve frame defines a valve opening. The valve plates are formed with protrusions. Each of the valve plates has a connecting end that is formed with a notch. The connecting ends are connected to each other. The protrusions protrude from peripheries of the notches. Each of the protrusions has a contact end. The contact ends cooperatively define a gap therebetween. The valve plates are co-rotatable about an axis between a closed position, in which the valve plates substantially close the valve opening, and an opening position, in which the valve plates open the valve opening. The gap has a width varying in response to co-rotation of the valve plates between the opening position and the closed position.

A check valve comprises a valve body defining a valve opening and a pair of valve elements mounted so as to be movable from a closed position in which they close the valve opening to prevent fluid flow through the opening to an open position in which they permit fluid flow through the opening. The valve further comprises a one piece bridge element having first and second end portions mounted to the valve housing on opposite sides of the valve opening and an intermediate portion extending between the end portions. The intermediate portion acts as a stop for the valve elements in their open position. A shaft mounting the valve elements for pivotal movement between their open and closed positions, is supported in the end portions of the bridge element. Fasteners for attaching the bridge element to the valve housing overlap the ends of the valve shaft thereby retaining it in the bridge element.