A substrate processing system includes a gas supply unit having a first gas flow channel. A second gas flow channel of a flow rate measurement system is connected to the first gas flow channel. The flow rate measurement system further includes a third gas flow channel connected to the second gas flow channel, and a pressure sensor and a temperature sensor that measure a pressure and a temperature, respectively, in the third gas flow channel. In a method, a flow rate of a gas output from a flow rate controller of the gas supply unit is calculated using a build-up method. The flow rate of a gas is calculated without using the total volume of the first gas flow channel and the second gas flow channel and temperatures in the first gas flow channel and the second gas flow channel.

A flow member (200) is for a flow assembly (100) of a pressure support system (2). The pressure support system includes a patient interface device (6), a flow generator (4), and a coupling conduit (8). The flow assembly includes a cover (102) and a sensing assembly (110). The sensing assembly has a flow sensor (114) having flow sensing components (118,120). The flow member comprises: a body (202) comprising: a mounting portion (204) connected to the cover, thereby enclosing the sensing assembly, a gas conduit (206) at least partially overlaying the mounting portion, the second conduit fluidly coupling the first conduit to the flow generator, and a number of flow conduits (208,210) each extending transverse to the gas conduit (206) and receiving a corresponding flow sensing component. Each flow conduit terminates at a distal end portion (209,211) in fluid communication with the gas conduit (206), each distal end portion being spaced a distance from the gas conduit (206) and located internal with respect thereto.

A flow member (200) is for a flow assembly (100) of a pressure support system (2). The pressure support system includes a patient interface device (6), a flow generator (4), and a coupling conduit (8). The flow assembly includes a cover (102) and a sensing assembly (110). The sensing assembly has a flow sensor (114) having flow sensing components (118,120). The flow member comprises: a body (202) comprising: a mounting portion (204) connected to the cover, thereby enclosing the sensing assembly, a gas conduit (206) at least partially overlaying the mounting portion, the second conduit fluidly coupling the first conduit to the flow generator, and a number of flow conduits (208,210) each extending transverse to the gas conduit (206) and receiving a corresponding flow sensing component. Each flow conduit terminates at a distal end portion (209,211) in fluid communication with the gas conduit (206), each distal end portion being spaced a distance from the gas conduit (206) and located internal with respect thereto.

The invention relates to a method for determining a volumetric and/or mass flow rate of a medium (M) flowing in a tube (20), wherein a density and/or a viscosity of the fluid (F) is/are determined by means of a MEMS sensor chip (30), wherein the medium (M) flowing in the tube (20) at least partially flows through a measuring channel (31) of the MEMS sensor chip (30) to determine the density and/or the viscosity of the fluid (F), and wherein the volumetric and/or mass flow rate of the medium (M) is determined regardless of the medium by means of a detected pressure drop (|p2p1|) over the measuring channel (31) of the MEMS sensor chip (30) and the density and/or viscosity determined by the MEMS sensor (30).

The invention relates to a method for determining a volumetric and/or mass flow rate of a medium (M) flowing in a tube (20), wherein a density and/or a viscosity of the fluid (F) is/are determined by means of a MEMS sensor chip (30), wherein the medium (M) flowing in the tube (20) at least partially flows through a measuring channel (31) of the MEMS sensor chip (30) to determine the density and/or the viscosity of the fluid (F), and wherein the volumetric and/or mass flow rate of the medium (M) is determined regardless of the medium by means of a detected pressure drop (|p2p1|) over the measuring channel (31) of the MEMS sensor chip (30) and the density and/or viscosity determined by the MEMS sensor (30).

A reference volume for use with pressure change flow rate measurement apparatus has an internal structure comprising elements with cross section and length comparable to the cross section and length of adjacent interstitial fluid regions. The reference volume may have one or more heat conduction elements exterior to and in good thermal contact with a corrosion resistant material that defines the internal fluid holding region.

A reference volume for use with pressure change flow rate measurement apparatus has an internal structure comprising elements with cross section and length comparable to the cross section and length of adjacent interstitial fluid regions. The reference volume may have one or more heat conduction elements exterior to and in good thermal contact with a corrosion resistant material that defines the internal fluid holding region.

Mass flow verification systems and apparatus verify mass flow rates of mass flow controllers (MFCs) based on pressure decay principles. Embodiments include a location for coupling a calibrated gas flow standard or a MFC to be tested in a line to receive a gas flow from a gas supply; a control volume serially coupled to the location in the line to receive the gas flow; a flow restrictor serially coupled to the control volume; a pump serially coupled to the flow restrictor; and a controller adapted to allow the gas supply to flow gas through the mass flow control verification system to achieve a stable pressure in the control volume, terminate the gas flow from the gas supply, and measure a rate of pressure decay in the control volume over time. Numerous additional aspects are disclosed.

Mass flow verification systems and apparatus verify mass flow rates of mass flow controllers (MFCs) based on pressure decay principles. Embodiments include a location for coupling a calibrated gas flow standard or a MFC to be tested in a line to receive a gas flow from a gas supply; a control volume serially coupled to the location in the line to receive the gas flow; a flow restrictor serially coupled to the control volume; a pump serially coupled to the flow restrictor; and a controller adapted to allow the gas supply to flow gas through the mass flow control verification system to achieve a stable pressure in the control volume, terminate the gas flow from the gas supply, and measure a rate of pressure decay in the control volume over time. Numerous additional aspects are disclosed.

There is provided a fluid sensing apparatus comprising a fluid flow channel, at least one fluid conduit in fluid communication with the fluid flow channel, and a fluid sensor having a casing and at least one sensor port in fluid communication with the at least one fluid conduit and providing access into the casing. The fluid sensing apparatus also includes a pressure compensation chamber in which the casing of the fluid sensor is enclosed. The apparatus further includes at least one pressure compensation conduit in fluid communication with the pressure compensation chamber and with the fluid flow channel. Also provided is a mass flow controller including such a fluid sensing apparatus.