The present invention provides a MEMS thermal flow sensor or meter for measuring the flow rate of a fluid without need for calibration of the flow sensor for that particular fluid. A response curve is determined by plotting the sensor output voltage against the volume flow rate divided by fluid thermal diffusivity for a calibration fluid of known thermal diffusivity, and storing response curve data in memory. A conversion factor is employed to provide a measure of correct flow rate of an unknown fluid. This conversion factor is derived from the ratio of the thermal time constant of the calibration fluid to the thermal time constant of the measured fluid, the time constants being measured at zero flow. These time constants are stored in memory. This conversion factor in conjunction with the response curve data is utilized by the processor to produce the correct flow rate. The invention also encompasses a method for measuring fluid flow rate of fluids of differing properties without necessity of a separate flow calibration for each fluid.

Provided is an intake air temperature detection apparatus mounted integrally with a flow rate measurement apparatus, the intake air temperature detection apparatus having temperature measurement precision improved by increasing thermal responsiveness of an intake air temperature detection part that is arranged in a measurement passage of the flow rate measurement apparatus and detects a temperature of intake air, which is a fluid to be measured. The intake air temperature measurement apparatus includes: the intake air temperature detection part for detecting a temperature of the intake air in the measurement passage of the flow rate measurement apparatus; and an intake air temperature detection circuit part arranged in a circuit accommodating part of the flow rate measurement apparatus, for generating a signal obtained by carrying out phase lead correction on a signal representing a result of detection by the intake air temperature detection part.

Flow restriction differential pressure and a third tap differential pressure for a pipe are used to determine a pressure loss ratio for the pipe/system that includes a flow restriction. The pressure loss ratio is used to determine whether liquid is present in the pipe. If liquid is present in the pipe, a value of the Lockhart-Martinelli parameter is determined and used to (1) correct gas flow measurement for the pipe and (2) determine a liquid flow rate in the pipe.

A high-temperature resistance is disposed in an internal passage and has its energization controlled based on an intake-air flow rate in the passage to increase/decrease a heat generation amount. A first low-temperature resistance constitutes a bridge circuit which has its energization state changed according to the heat generation amount of the high-temperature resistance. The first low-temperature resistance varies its resistance value according to intake-air temperature. A second low-temperature resistance is an element, which is not incorporated into the bridge circuit and varies its resistance value according to intake-air temperature to increase/decrease an energization amount. The second low-temperature resistance is provided on a substrate. Another bridge circuit produces an intake air amount detection signal using an electrical signal generated by operation of the high-temperature resistance and the first low-temperature resistance. A digital circuit uses an electrical signal produced by the second low-temperature resistance as an intake temperature detection signal.

In a capillary heating type thermal type mass flow meter comprising a sensor configured to detect temperature and pressure of a fluid and a correction means configured to correct a mass flow rate based on said temperature and said pressure, change rates of the mass flow rate of the fluid with respect to temperature and pressure have been previously acquired, and the mass flow rate is corrected based on said temperature and said pressure as well as these change rates. Thereby, the mass flow rate can be measured accurately and simply even when the temperature and/or pressure of the fluid, whose mass flow rate is to be measured, change.

A system includes a control system and a field device. The control system is configured to communicate data with the field device. The field device determines whether a deviation in a measurement accuracy of a first characteristic curve for a flow profile of a process fluid is detected while monitoring an inline condition of the process fluid. The field device determines whether the deviation is greater than an application tolerance. The field device also performs an inline recalculation for a new characteristic curve according to present flow condition detected in measurements of the flow profile when the deviation is greater than the application tolerance. The field device calculates a flow rate of the process fluid using the new characteristic curve.

The present invention provides an automated meter station monitoring system for a fluid comprising a processor having algorithms for verifying performance of a fluid flow measurement system. A pressure sensor is operatively connected to the processor to measure the pressure of the fluid. A temperature sensor is operatively connected to the processor to measure the temperature of the fluid. A gas chromatograph is operatively connected to the processor to monitor changes in gas composition and chromatograph response factors of the fluid. An ultrasonic meter is operatively connected to the processor to monitor the velocity of the fluid, speed of sound of the fluid, and meter diagnostics. A flow computer is operatively connected to the processor to record pressure of the fluid, record temperature of the fluid, record gas composition of the fluid, calculate compressibility ratio of the fluid, calculate standard flow rate of the fluid, and calculate energy rate of the fluid.