Flow Meters Types and Terms

  • Air flow meters are used to measure the flow of air.
  • Coriolis mass flow meters are used to measure the force of acceleration resulting from a moving object towards or away from the center of rotation.
  • Differential pressure flow meters are used to measure the flow of fluids and gases in a pipe by introducing constriction that causes the pressure to drop. The pipe must be clean to result in accurate measurements.
  • Insertion flow meters measure flow at one position in a pipe, and then, based on the measurement, they estimate the flow rate for the entire pipe.
  • Magnetic flow meters measure by creating a magnetic field that is channeled into the liquid and causes a voltage signal to be sensed that is proportional to the flow of liquid.
  • Mass flow meters are used to measure gas flow and are one of the more popular flow meters. This meter is relatively unaffected by changes in temperature or pressure in the tube or pipe.
  • Open channel flow meters are used to measure the flow of liquids when they are open to the atmosphere.
  • Peak flow meters are used by patients with asthma or other lung disorders to measure the amount of air patients take into their lungs. These flow meters allow physicians to determine the severity of the illness.
  • Positive displacement flow meters trap liquid to measure its flow by rotating parts that move between seals and the meter body.
  • Rotometers have a rotating float that moves vertically through a tapered tube.
  • Sight flow indicators allow the operator to view the liquid as it is moving. Some models come equipped with lights to enhance the visibility of the fluids.
  • Target flow meters measure the amount of force that is exerted on a target in a particular liquid or gas. This should not be used to measure high viscosity liquids because the target can be damaged.
  • Thermal flow meters are meters that use thermal properties of fluids to measure the flow. The meter is heated and as the liquid flows by, it can tell the flow rate by the amount of heat lost.
  • Turbine flow meters consist of a rotor that measures the fluid when it passes through the blades. The blade speed is translated into the speed of the fluid
  • Ultrasonic flow meters use sound to determine flow rate. Both Doppler Effect meters and time-of-flight meters are different kinds of this type.
  • Variable area flow meters measure by letting the flow stream change the opening in the meter with a movement of an internal part.
  • Vortex and fluid flow meters generate oscillations as a result of the flow that allows a measurement to be taken.
  • Water flow meters are flow meters designed for measuring flow rates of water in various channels, tubes, partially filled pipes, streams, and rivers.


Flow Meter Terms

Absolute Pressure - Atmospheric pressure plus gage pressure.

Accumulator - Area where fluid is under pressure and stored as a source of power.

Control Point - The temperature an instrument needs to maintain to perform its designated function.

Coriolis Force - The force that occurs when a mass has a velocity moving outward in a rotating plane.

Counter Weight - A mass that is added to a particular substance to create a more balanced and stable apparatus.

Current - The flow rate of electricity.

Density - A substance's mass per unit of volume.

Flow - The travel of materials in response to a force, such as pressure.

Flow Nozzle - A constriction made of a contoured plate that forms a hole for the flow stream so a measurement can be taken.

Flow Rate - The velocity of flow.

Head-Loss - The loss of pressure in a flow system that is measured with a length parameter (such as amount).

Hot-Tap - Allows for a flow meter to be inserted or removed without causing a complete system shutdown.

Integrator/Totalizer - A device that measures the total flow of fluids.

Manometer - Measures fluid pressure. This is a U-shaped tube containing liquid which adjusts with the pressure in the tube.

Mass Flow Rate - The volumetric flow rate of a liquid or gas times its density, expressed as pounds per hour or kilograms per minute.

Potential Energy - The potential of energy when a liquid is in a position or height above a place to which it can potentially flow.

Transducer - The part of a flow meter that senses fluid as it passes through the device.

Transmitter - The part of a flow meter that produces the usable flow information from the transducer.

Weldolet - A connection for a metal pipe that is used to aid as a fitting for insertion-type sensors or meters.