Flapper valves may be provided with flapper assemblies. The flapper assemblies comprise a bracket, a flapper, a bearing, and a pin. The bracket has a pair of knuckles with a bore extending through the knuckles. The flapper has a knuckle with a bore. The bearing is mounted in the flapper knuckle bore and has a bore extending through it. The pin extends through the bores in the bracket knuckles and the bearing bore. The pin and the bracket are locked to each other. Clearance between the pin and the bearing bore allows relative rotation between the flapper and the pin. The flapper thus is mounted to the bracket for pivoting movement between a closed position, in which the flapper is adapted to bear on a seat in the flapper valve, and an open position, in which the flapper is adapted to pivot away from the seat.

Embodiments relate to a check valve and methods of making a check valve that include a valve body having an inlet end, an outlet end, a flow bore that extends between the inlet and outlet ends, a cavity which intersects the flow bore, and an opening which is connected to the cavity. In certain embodiments, the check valve further includes a cap removably secured in the opening, a seat cartridge disposed in the cavity, wherein the seat cartridge comprises a chamber with a flow bore, a retainer ring positioned in the valve body between the cap and the seat cartridge, a pivot pin retainer seal provided between the retainer ring and the valve body, wherein the pivot pin retainer seal comprises one or more protrusions extending outwardly in a radial direction from the retainer ring to seal on the valve body, and a flapper pivotally connected to the retainer ring, wherein the flapper is pivotable through the chamber between a closed position in which the flapper is positioned against a shoulder in the seat cartridge and an open position in which the flapper is displaced from the shoulder.

The invention relates to a closure device (28) for a filter unit (1) for the mutual and releasable insertion into a return air duct or exhaust air duct (2) of a barrier system (3), comprising a main body (30), an opening (6) in the main body (30) that can be peripherally bounded by an annular seal (11), a lid (10) that can be switched between an open position in which the opening (6) is open and a closed position in which it bears in a sealing manner against the annular seal (11) in order to selectively open and close the opening (6) and that has passing through it an imaginary longitudinal axis (A), wherein the lid (10) is connected in an articulated manner to the main body (30) so as to be able to pivot by means of at least one rotary articulation (40) through which there passes a pivot axis (S). The lid (10) is designed so as to be able to pivot at least double-eccentrically, wherein the first eccentricity arises from the fact that the pivot axis (S) is arranged at a distance (A.sub.1) from a plane (E.sub.1) in which a closure section ( ) of the lid (10) lies, and wherein the second eccentricity arises from the fact that the pivot axis (S) is arranged at a distance (A.sub.2) from a vertical longitudinal mid-plane (E.sub.2) which passes vertically through the center of the lid (10) when the latter is in its closed position.

A valve assembly with a spring retention assembly including an elongated cylinder portion having an open threaded end and a closed end and an elongated piston portion having a free end and a threaded tab end configured to thread through the open threaded end and, thereby, be slideably captured in the cylinder portion. A spring couples to the body portion and the piston portion to provide a force to urge the body portion and the piston away from one another, wherein the closed end and the free end are similarly shaped so that the spring retention assembly can be reversibly mounted to a valve member that can also be reversibly mounted.

A valve device includes: a housing H, defining an upstream side passage 41a and a downstream side passage 22a through which a fluid passes, a valve accommodation chamber h1 interposed between the upstream side passage and the downstream side passage, and an opening part 41b located at a downstream end of the upstream side passage; and a cantilevered valve body 30, disposed in the valve accommodation chamber, and having a support part 32 that is elastically deformable and cantilevered and, on a free end side of the support part, a valve part 31 that is plate-shaped and opening and closing the opening part. In the valve device, the downstream side passage 22a is formed to expand in a direction along a plane 31a, 31b of the valve part in a state in which the valve part 31 is fully opened.

The invention relates to a closure device (28) for a filter unit (1) for the mutual and releasable insertion into a return air duct or exhaust air duct (2) of a barrier system (3), comprising a main body (30), an opening (6) in the main body (30) that can be peripherally bounded by an annular seal (11), a lid (10) that can be switched between an open position in which the opening (6) is open and a closed position in which it bears in a sealing manner against the annular seal (11) in order to selectively open and close the opening (6) and that has passing through it an imaginary longitudinal axis (A), wherein the lid (10) is connected in an articulated manner to the main body (30) so as to be able to pivot by means of at least one rotary articulation (40) through which there passes a pivot axis (S). The lid (10) is designed so as to be able to pivot at least double-eccentrically, wherein the first eccentricity arises from the fact that the pivot axis (S) is arranged at a distance (A.sub.1) from a plane (E.sub.1) in which a closure section ( ) of the lid (10) lies, and wherein the second eccentricity arises from the fact that the pivot axis (S) is arranged at a distance (A.sub.2) from a vertical longitudinal mid-plane (E.sub.2) which passes vertically through the center of the lid (10) when the latter is in its closed position.

A backflow prevention assembly has a body having a first bucket with a sidewall extending between a closed end and an open end along a first bucket axis, a first conduit extending from an inlet of the sidewall of the first bucket, and a second bucket having a sidewall extending between a closed end and an open end along a second bucket axis. A second conduit extends between an outlet of the sidewall of the first bucket and an inlet of the sidewall of the second bucket, and a third conduit extends from an outlet of the sidewall of the second bucket. The conduits extend along a conduit axis that is perpendicular to the bucket axes. The valve assembly includes covers secured over the open ends of the buckets and a valve member located in each bucket that is biased to prevent reverse flow through the inlets of the buckets.