Just like the name suggests, a flow meter is an instrument used to measure linear and nonlinear, mass or volumetric flow rate of a liquid or gas. In this case we look at water flow meters. The quantification of bulk fluid movement is fluid measurement. Through measuring the velocity of a fluid over a known area, flow can be measured. In choosing water flow meters, one should consider factors such as; spare parts availability, familiarity of personnel with the device, and their experience with calibration and measurement.
To fully evaluate the nature of the process and of the overall installation, time should be invested. this helps a person in choosing a good flow meter. Whether the flow information should be continuous or totalized and whether the information is needed remotely or locally is what one should determine first while choosing a flow meter. After asking these questions, an evaluation of the fluid process and of the piping that will accommodate the flow meter takes place.
Included in the different types of mag flow meter, is mechanical flow meter and it works on the principle of positive displacement. The most used in domestic measurement of water is a piston meter or a rotary piston. It works by a piston rotating within a chamber and for each rotation some amount of water passes.
An oval gear meter is another type of flow meters. Herein fluid gets into one chamber then into a measurement chamber and then to the outlet. As the cycle continues, fluid is metered in alternating measurement chambers. In the rotating gears there are permanent magnets that transmit signal to an electric reed for flow measurement. Though claims are made for high performance, they are not as precise as sliding vane design.
Measurement chambers of gear meters which is the other type are made up of gaps between the gears and the teeth and this makes the difference between them and oval meters. Flow meter’s other type is helical gear flow meter. The rotation of rotors happens in a continuous fashion hence flow rate is measured in this way. The variable area meter is also called a rotameter and it is another type. This type of a meter consists of a tapered tube mostly made of glass with float inside which is pushed by fluid flow and pulled down by gravity. Some floats are designed to spin visibly in the fluid stream so as to help the user determine whether the float is stuck or not. This is the commonly used meter with water.
The list is endless but just to mention the other types of flow meters are; turbine flow meter, nutating disk meter, single jet meter, Woltman meter, multiple jet meter and many more.