A flow meter is a device that measures flow. Flow measurement is the quantification of bulk fluid movement (liquid or gas). Flow can be measured in a variety of ways.
Mechanical (Positive-displacement) flowmeters are best compared to a bucket and a stopwatch. The stopwatch is started when the flow starts, and stopped when the bucket reaches its limit. The volume divided by time gives the flow rate.
Pressure-based Meters rely on Bernoulli’s principle to derive the dynamic pressure. Optical flowmeters use light to determine flow rate. A direct measurement of mass flow can be obtained with Coriolis flow meters. These flowmeters use the Coriolis effect that causes a laterally vibrating tube to distort to measure mass flow.
If you’re doing gas chromatography, you must routinely measure gas flows when setting up an instrument, developing a method, or troubleshooting. Modern GCs rely on electronic pressure control (EPC) for setting flow rates. However, a flowmeter is still an essential tool to have- especially while troubleshooting. Also, many older GCs that are still in use don’t have EPC, which requires manually setting flows with a flowmeter.
Types of Flowmeters
There are generally two types of gas flowmeters- volumetric and mass. Both types measure the amount of gas exiting a column or split vent in a specific time period. If the amount of gas is measured in units of volume, the flow rate is volumetric based. The most common device for measuring a volumetric flow rate is a bubble flowmeter. If the amount of gas is measured in units of mass, the flow rate is mass based. The most common device for measuring mass flow is a thermal flowmeter (more commonly called mass flowmeter).
Top Flowmeter Manufacturers
HiTechTrader offers a variety of flow meters to meet your flow measurement needs. Hewlett Packard, Humonics, Brooks Instruments, Kobold, Sensus, and ISCO are all excellent manufacturers.
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