Measurement and Control

Flow measurement has a long history extending over a period of about 3000 years, but it was only just over 200 years ago that the subject was first studied on a scientific basis and it was only 20 years ago that a surge of new techniques became available. Today there is a wide selection of methods and equipment to enable flow to be measured whether the medium is in the form of a liquid, gas, vapour or solid, or any combination thereof. According to the application, volumetric flow rate can be measured over a range exceeding 10⁻⁵m³/h to 10⁶m³/h which in everday terms is equivalent to a cupful per day to the flow of a very large river. The price of a flowmeter can be as small as a few pounds or in excess of £1 million depending on the accuracy and capacity required. References are made to about 50 types of flow metering devices which can be classified into 11 groups.