A manifold for an air massage system of a tub may have a housing defining an inner cavity having an air inlet configured to be pneumatically connected to a pressure source. Air outlet(s) is pneumatically connected to one or more outlets of the tub. A check valve(s) is in the inner cavity of the housing, the at least one check valve being positioned between the air inlet and the at least one air outlet relative to an air flow through the housing, the at least one check valve allowing fluid communication from the air inlet to the at least one air outlet and blocking water from flowing from the at least one air outlet to the air inlet. A width of the manifold is less than a height of the manifold.

Described is a check valve having a valve housing, a valve seat, a ball and a spherical loading element. The valve seat is disposed proximate to a first end of the bore. The ball is disposed in the bore and is movable between a closed position in which the ball is received against the valve seat and prevents a flow of fluid through the bore and an open position in which the ball is displaced from the valve seat and allows fluid to flow through the bore. The spherical loading element is disposed in the bore and is movable between the ball and the second end of the bore. The spherical loading element applies a supplemental force to move the ball against the valve seat during closing of the check valve. The check valve provides a low and predictable cracking pressure which does not vary significantly between similarly manufactured valves.

A device for holding a hydraulic cylinder stem in position includes a hydraulic block having series-connected primary and secondary check valves. The latter includes a secondary control stem having a secondary valve body and a seal. A first throttle upstream and a second throttle downstream are closed in a secondary control stem closed position where the seal tightly blocks the secondary check valve, each throttle having a tiny throttle closing gap, preferably 0.1 mm or less. The control stem can move axially into an intermediate position where the throttles remain closed, that is, have a tiny closing gap, but valve body and seal are lifted from a secondary valve seat. The control stem can be moved further into an opening position where the throttles are open, each having an opening gap much larger than the closing gap, and the valve body and seal are lifted from the valve seat.

Provided is an check valve. The check valve comprising a plurality of valve parts in which an internal flow path is selectively open/closed by opening/closing members, wherein the plurality of the valve parts are stacked in a line. And the check valve further comprising a cylinder-shaped valve housing open on one side, wherein each opening/closing member of the plurality of valve parts is received from the open one side of the valve housing.

Apparatuses and methods related to a high pressure fluid processing device having a dual check valve setup that can be quickly and easily maintained with replacement parts are disclosed herein. In a general example embodiment, a high pressure processing device includes a body including a first surface having a first recess, a second surface having a second recess, and a third surface having a third recess, a first subassembly at least partially inserted into the first recess of the body, the first subassembly including a first check valve, a second subassembly at least partially inserted into the second recess of the body, the second subassembly including a second check valve, and a third subassembly at least partially inserted into the third recess of the body, the third subassembly coupling the body to a fluid driving mechanism, wherein the first subassembly, second subassembly and third subassembly are configured to be independently attachable to and detachable from the first recess, second recess and third recess, respectively.

Embodiments of air admittance valve assembly and plumbing system incorporating the same are provided herein. In some embodiments, a valve assembly to allow or stop a flow for use with enclosed environment includes a housing having, an inlet disposed at a first end of the housing fluidly coupled to environment surrounding housing, an outlet disposed at a second end of housing fluidly coupled to enclosed environment, and an interior volume divided into a first zone, a second zone, and a third zone, a first valve having a first valve seat and a first sealing member urged by an existing force between a closed or open position; and a second valve having a second valve seat and a second sealing member urged by an existing force between a closed or open position.

A downhole valve includes a housing, and a sleeve positioned within the housing. The sleeve has a first axial end, a second axial end, and a seat positioned between the first and second ends. The sleeve defines an opening facing in a radial direction. The sleeve prevents fluid flow in an opposite radial direction, away from the opening. The valve also includes a retaining element coupled to or integral with the sleeve, and a first obstructing member positioned in the sleeve and movable between the seat and the retaining element. In a first position, the first obstructing member engages the seat and prevents fluid flow through the housing. In a second position, the first obstructing member is separated apart from the seat such that at least a portion of the opening is axially between the first obstructing member and the first obstructing member.

Disclosed is a check valve and a modulator block including the same. An embodiment of the present disclosure provides a check valve comprising a valve housing including first and second internal flow passages each formed to pass through an interior of the valve housing and having an inlet through which a fluid is introduced and an outlet through which the fluid is discharged; a first opening and closing member provided in the first internal flow passage and opened and closed by a hydraulic pressure of the fluid; a second opening and closing member provided in the second internal flow passage and opened and closed by the hydraulic pressure of the fluid; and a stopper member press-fitted to the valve housing.

A valve injector (10) comprising: a body (12) defining a fluid conduit (14), the fluid conduit (14) accommodating first, second and third checks (16, 18, 20), the first check (16) being disposed within the fluid conduit (14) towards a first end (10a) of the injector (10), the second check (18) being disposed towards a second end (10b) of the injector (10), distally from the first end (10a), and the third check (20) being located between said first and second check (16, 18).

An apparatus to allow or stop a flow into an enclosed environment or piping system comprises: (a) a housing having an upper flow passage, a middle flow passage, a lower flow passage; (b) a first valve seat, wherein the first valve seat is between the upper flow passage and the middle flow passage, and wherein a first opening is formed on the first valve seat; (c) a first rotary valve inside the housing, moving inside the upper flow passage and above the first valve seat; (d) a second valve seat, wherein the second valve seat is between the middle flow passage and the lower flow passage, wherein a second opening is formed on the second valve seat; and (e) a second rotary valve inside the housing, moving inside the middle flow passage and above the second valve seat.