# Flow Measurement Device

## Flow Measurement Device

in physiology, an instrument used for measuring the volume rate of blood flow in a blood vessel (flowmeter) or for measuring expired air flow (pneumotachometer). The volume rate of blood flow, that is, the amount of blood that passes through a cross section of a blood vessel per unit time (milliliters per minute, or ml/min), is usually determined by the linear velocity rate of blood as it passes through a segment of pipe of a known cross section. The linear rate of blood flow, that is, the average velocity of the flow of blood particles in a given section of a blood vessel, is measured in the following ways: (1) by the rate of the movement of an air bubble that is introduced into the blood flow, (2) by the difference in blood pressure at two points that are located before and after a constricted section of the pipe through which the blood is flowing (the pneumotachometer has a similar circuit), (3) by the degree of cooling of the heated junction of a thermocouple or thermistor caused by the flowing blood, (4) by the difference in the rates of dissemination of ultrasound in the blood as the ultrasound moves against or with the blood flow, and (5) by the value of the electrical potential of the blood that moves perpendicularly to the magnetic field of a strong electromagnet. The electrical potential of the blood is comparable to that of an electrolytic conductor.

Other types of flow measurement devices used include blood flowmeters, rotameters, turbine meters, and gas flowmeters.

References in periodicals archive ?
It consists of multiple nozzles for measuring a wide range of flow rates with less error and a speed-controlled turbo fan to control the exit pressure so the pressure of the outlet is maintained at atmospheric pressure that then becomes the same as the original pressure before the flow measurement device is applied.
Eventually a flow cross was introduced to allow a VAV box to be pressure independent to duct pressure, but it was still not a flow measurement device.
Using a flow measurement device with an accuracy of [+ or -] 1% means the uncertainty in money equals more than \$30,000 per hour.
The CentriFeeder[TM] with Integrated Control Valve (ICV) is both a controlled feed device and a mass flow measurement device in a single multi-functioning unit that measures and controls the flow of any dry, free-flowing solid.
Purpose: To assess the reproducibility of QA measurements using the Transonic[R] access blood flow measurement device in individual patients over multiple measures.
Two centuries ago, Italian scientist Giovanni Battista Venturi developed a mass flow measurement device for incompressible fluids based on the characteristic pressure drop that fluids exhibit when accelerated to a higher velocity.
In the 3rd quarter of 2009 we announced that we discontinued commercial activities related to the blood flow measurement device business and incurred a non-cash impairment charge of \$1.
The effect of the resistance of the flow measurement device on the airflow through a grille is sometimes accounted for by a K-factor.
The long term monitoring and detection of process effects are advantageous for any flow measurement device.
In the late 1990s, J&W Scientific acquired Humonics, a gas and liquid flow measurement device company, and R&D Separations, a specialized manufacturer of carrier gas purification traps and systems.
Over the following decade and a half, the practical challenges of making the technology commercially viable as a flow measurement device were described and addressed through innovation and development that resulted in production of a gas ultrasonic meter that utilizes:

Site: Follow: Share:
Open / Close