What is a Flow Transmitter?

A flow transmitter is a instrument that takes a range of flow and converts it into a signal for use in a control system.

As a simple example, 0-10m³/h -> 4-20mA (an industry-standard signal).

Such an instrument is usually found in, on or adjacent to a pipeline, depending on measuring technique, or could also be found in or over flow an open channel.

Techniques of measurement include:

• Variable area
• Electromagnetic
• Differential pressure across a restriction
• Ultrasonic
• Pelton wheel or other turbine/impeller
• Vortex shedding
• Coriolis mass

There is also the Calorimetric Principle which uses thermal dynamics to detect flow speed and transmits when the flow is higher or lower than a set point. For example: wet your finger and hold it in the air; the speed at which it cools down relates to the amount of flow in the pipe.

In Simplest terms, An item that 'transmits flow'

How's that for Simple.....

PWSlack has it mainly right, but the reason it is referred to as a transmitter and has a current output is to allow for monitoring from long distances vs. a transducer which would have a voltage output and used for localized montoring. They both convert from one form of energy to another, but voltage outputs will have voltage drops over distance whereas current outputs are much less affected.