Selecting a Flowmeter on Amazon.com
A flowmeter, or flow meter, is an instrument for measuring the volume, mass, or velocity of gas or liquid flowing through piping. While most flow meters are designed for either gases or liquids, some models can be used with both. A flow meter for gases is commonly referred to as an air flow meter, while one for liquids is commonly referred to as a water meter or water flow meter. Flow meters are available with an analog scale, a digit counter, or a digital readout, and some have a signal output that transmits data to a remote device. They are used in applications such as water treatment, utilities monitoring, manufacturing, food processing, mining, refining, and medical research.
Among the factors to consider when selecting a flow meter are the type of measurement being made (volume, mass, or velocity), the type of media (liquid or gas) being measured and its compatibility with the meter's wetted parts, the required flow range and accuracy, and the pressure rating. Certain meters can handle slurries and media with particulates, while a water meter may only be compatible with clear liquids. Most flow meters have pipe fittings for inline installation; the type and size of the fittings varies from meter to meter. A flow meter may be immersible or have fittings for panel mounting.
There are various types of flow meter. A variable area flow meter, or rotameter, has a tapered tube and a float that indicates readings on an analog scale. It is mainly used for liquid flow measurements and is available in models for horizontal or vertical mounting. An ultrasonic, or Doppler, flow meter uses sound waves to measure the velocity of liquid flow. Thermal mass flow meters heat gas or liquid at one point within a pipe and have a temperature sensor to measure heat loss as the media moves through the pipe. Turbine flow meters determine volume by counting rotations of the rotor as liquid flows through the blades of the turbine. Low flow rate meters are often used for fuel monitoring in engines.