A pressure gauge and/or relief valve which may be used in a single-use fluid system, such as a sterilizable fluid system. The pressure gauge and/or pressure relief valve may be formed of a disposable and/or sterilizable material, such as a non-metallic (e.g., polymeric) material. The material of the pressure gauge and/or pressure relief valve may be compatible with the material of a fluid-containing structure of the fluid system, such as to be bonded (e.g., welded) therewith. The fluid-containing structure may be retrofitted to integrate the pressure gauge and/or pressure relief valve therewith. The pressure gauge and/or pressure relief valve may have a simple configuration, such as a housing with a movable element therein. The movable element moves with respect to the housing to indicate pressure and/or to relieve pressure from within the housing and/or fluid-containing structure.

An indicator adapted to provide a visual indication of an over pressure situation in a system. The indicator (also referred to as a pop indicator), includes a main body, a piston that is disposed in the main body, and one or more O-rings disposed around the piston. Initially, the piston is in a first position where the piston is retracted into the body. However, when an over pressure situation occurs, the pressure causes the piston to move in a direction out of the main body against a friction force created by the O-ring. When the piston is moved, i.e., popped, then end of the piston extending out of the body provides a visual indication.

An air compressor having a pressure gauge, the pressure gauge contains: a hollow tube, a drive element, an anti-leak spring, a resilient element, and a cap. The hollow tube includes an accommodation chamber, a connector having a conduit, and a display unit. The drive element includes a protection unit, a first open segment, a second distal segment, a receiving portion, a hollow extension, and a protrusion. An anti-leak spring is received in the hollow extension of the drive element, a first end of the anti-leak spring abuts against the protrusion, and a second end of the anti-leak spring contacts with the protection unit. The resilient element is received in the receiving portion of the drive element. The cap includes a seat, a push bolt, and multiple passages. An end of the resilient element contacts with the cap.

A display structure of a pressure gauge of an air compressor, the air compressor is received in an accommodation box, and a scale portion of the pressure gauge is viewable via a displaying opening of the accommodation box, the pressure gauge includes a cylindrical body which is transparent and is formed in a pen shape, and the pressure gauge includes a colored O-ring configured to indicate a pressure value of the scale portion. The scale portion is not printed on the cylindrical body of the pressure gauge and includes a transparent panel on which the pressure value of the scale portion is marked on an internal face of the transparent panel, and the internal face faces the cylindrical body of the pressure gauge.

A pressure gauge with divisional scale includes a piston tube, a piston, an elastic member, a rotating member and a pointer connected with the rotating member. The piston has plural transmission portions and is slidably disposed in the piston tube. The elastic member is disposed inside the piston tube and abutted against the piston. The rotating member has plural gears sequentially and respectively engaged with the transmission portions when the piston slides so as to drive the pointer to swivel, thereby achieving a pressure gauge with a single pointer indicating multiple pressure ranges.

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 pressure gauge adapted to be mounted in a containing recess of an air pump includes a housing arranged in the containing recess, a driving member movably arranged in the housing, a biasing member biasing the driving member toward the housing, a driven member configured to be driven to rotate by the driving member, a pointer needle connected with the driven member, a scale plate disposed between the driven member and the pointer needle, and a guiding member arranged between the housing and the driving member. The guiding member is configured to contact at least one of the housing and the driving member to remain the driving member moving relative to the housing in a straight direction.

Exemplary embodiments provide a packing leak detection system for leaks or discharge of a volatile material which discharge into the environment is subject to regulation. The system contains a compressor apparatus including a compressor cylinder, a compressor piston, a compressor piston rod positioned in a packing case, wherein a volatile material being compressed by the compressor apparatus leaks from the packing case. Also provided is a leak detector sized and configured to detect and monitor leaks of the volatile material from the packing case. Methods of assessing leaks of a volatile material subject to environmental regulation are also provided.

An improved air compressor includes a cylinder fitted with a piston body and an air storage container. The cylinder and the air storage container are detachably assembled to define an air chamber. A metal seat with a through hole is provided on top of the cylinder. A valve plug is spring-biased against the metal seat. The air storage container is provided with a pressure indicator, which includes a tube defining therein a first bore and a second bore, between which a tapered annular surface is formed. When the air pressure within the air storage container exceeds a predetermined pressure set for the air compressor, the pressure indicator allows excess air to flow into the first bore of the tube and sequentially pass through the tapered annular surface and an elongated opening to be released to the ambient environment, so that objects can be prevented from damages due to excessive inflations.

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.