A flow meter is shown. The flow meter includes a housing extending along an axis and defining an interior volume, the interior volume extending between an inlet port and an outlet port. The flow meter further includes an insert positioned within the interior volume and spaced apart from the housing, the insert extending along the axis. A first region between at least part of the insert and the housing along the axis defines a first flow pathway, and a second region within the insert and along the axis defines a second flow pathway.

An airflow measurement device that is configured to measure airflow in an air handling system. The airflow measurement device can include a flow conditioning plate formed with a plurality of plate apertures or holes. A flow sensor is associated with each aperture. The flow sensors can be any type(s) of flow sensors that are suitable for sensing or characterizing one or more aspects of air flowing into and through the apertures, such as pitot sensors, vane anemometers, hot wire anemometers, or the like. The flow sensors can be used to quantify the volumetric airflow rate of the airflow, the speed of the airflow, or any other variable of the airflow from which one can formulate a judgment about the operating efficiency of the air handling equipment.

A flow resistance insert of a flow rate measuring or flow rate control has contiguous discs between which at least one central axial flow duct is formed from which radial flow ducts branch off. The discs include alternating first discs and second discs. While the first discs are circumferentially closed ring discs, the second discs are circumferentially slotted one-piece ring discs.

A flow resistance insert of a flow rate measuring or flow rate control has contiguous discs between which at least one central axial flow duct is formed from which radial flow ducts branch off. The discs include alternating first discs and second discs. While the first discs are circumferentially closed ring discs, the second discs are circumferentially slotted one-piece ring discs.

Disclosed herein are an apparatus and method fluid flow measurements which include a pressure transducer and a flexible tube. The pressure transducer is tuned to measure flow speeds having a Reynolds number less than 100 and include an inlet. The flexible tube has a first end fluidly coupled to the inlet and a second end positioned adjacent to and in fluid communication with a plurality of fluid outlets of a microchannel flow structure. Each of the plurality of fluid outlets has a cross section defining an outlet area. The second end has a cross section defining a flexible tube area that is larger than the outlet area.

Disclosed herein are an apparatus and method fluid flow measurements which include a pressure transducer and a flexible tube. The pressure transducer is tuned to measure flow speeds having a Reynolds number less than 100 and include an inlet. The flexible tube has a first end fluidly coupled to the inlet and a second end positioned adjacent to and in fluid communication with a plurality of fluid outlets of a microchannel flow structure. Each of the plurality of fluid outlets has a cross section defining an outlet area. The second end has a cross section defining a flexible tube area that is larger than the outlet area.

Mass flow verification systems and apparatus may verify mass flow rates of mass flow controllers (MFCs) based on choked flow principles. These systems and apparatus may include a plurality of differently-sized flow restrictors coupled in parallel. A wide range of flow rates may be verified via selection of a flow path through one of the flow restrictors based on an MFC's set point. Mass flow rates may be determined via pressure and temperature measurements upstream of the flow restrictors under choked flow conditions. Methods of verifying a mass flow rate based on choked flow principles are also provided, as are other aspects.

Mass flow verification systems and apparatus may verify mass flow rates of mass flow controllers (MFCs) based on choked flow principles. These systems and apparatus may include a plurality of differently-sized flow restrictors coupled in parallel. A wide range of flow rates may be verified via selection of a flow path through one of the flow restrictors based on an MFC's set point. Mass flow rates may be determined via pressure and temperature measurements upstream of the flow restrictors under choked flow conditions. Methods of verifying a mass flow rate based on choked flow principles are also provided, as are other aspects.

A connecting apparatus for creating a connection to a measuring instrument or to a valve block/valve with a measuring instrument, and a connection to a pipeline or to a metering orifice device installed in a pipeline comprises: a first connecting device that provides a sealing connection to the pipeline or to the metering orifice device with a first recess extending through in the longitudinal direction, and a second connecting device that provides a sealing connection to the measuring instrument or to the valve block/valve with a second recess extending through in the longitudinal direction. The first and second connecting devices are interconnected with sealing effect. The connecting unit is designed so that the sealing connection can be created solely by rotation of the connecting unit without rotating the first and second connecting devices.

A connecting apparatus for creating a connection to a measuring instrument or to a valve block/valve with a measuring instrument, and a connection to a pipeline or to a metering orifice device installed in a pipeline comprises: a first connecting device that provides a sealing connection to the pipeline or to the metering orifice device with a first recess extending through in the longitudinal direction, and a second connecting device that provides a sealing connection to the measuring instrument or to the valve block/valve with a second recess extending through in the longitudinal direction. The first and second connecting devices are interconnected with sealing effect. The connecting unit is designed so that the sealing connection can be created solely by rotation of the connecting unit without rotating the first and second connecting devices.