Flow meter technology is one of those technologies that can either support or hinder the growth of other technologies. In fact much of the advances in flow meter technologies is a direct response to many needs in other industries including manufacturing, automotive and many others. For instance we wanted better cars and got them, now we want cars that are both more powerful as well as more fuel efficient and it took more than a handful of flow measuring, flow control, sensors and computer chips to deliver them.
The earliest uses for flow meters stem from a need to ration out water and trade in both solid and liquid products. A flow meter in those days was as simple as a large vat or other type of container that would be filled up to measure the amount of water to ration then released into a channel or other container. The need for great accuracy is not as it is today, giving some one a small amount more or less was no big deal.
Today we not only measure the flow of liquids but of gases and solids as well. We measure things in much smaller amounts and our measurements need to be as close to exact as possible with each generation of devices outperforming the previous. Much of what we see around us today would not be possible without the advances in flow meters.
Some common examples of flow meters include the pump at the gas station, your household water meter and your gas meter for natural gas. Your car is full of flow control devices and newer cars include flow control and sensors as part of its computer controller. Flow measurement is also used in places where failures could mean disaster including nuclear power plants, manufacturing operations and a great many more.
Inaccuracy in flow measurement or misinterpreting measurements can not only cost you a great amount of money over time, it can also spell disaster for equipment, product and even hazard to life. This is why it is important for all people that work around or with flow meters or the data provided by them to know about the basic types of meters and how they work.
From purchasing agents that should know something of what they purchase to the person that sweeps the floors at night, all should know about these sensitive and important devices. This site is set up to give the most basic introduction to flow meters and display a wealth of other information.
Basic flow meters
The most basic types of flowmeters are used with various liquids and some can be used with gases. Most of these flowmeters have some impact on the downstream flow from their installation. This reduction of the downstream flow may need to be compensated for upstream. Most of the devices listed in this section are mechanical.
Vortex Flow Meter
Commonly used to measure steam and also appropriate for water and other gases. Vortex flowmeters are used to measure volume and are often used with other devices like pressure and temperature sensors as part of a larger complex system controlled by a flow computer.
Variable Area Flow Meter
These are often called rotameters, they are used to measure flow rate of gases or liquids. They compare linear displacement to a known flow rate. The three basic times of variable area flow meters are rotameter, movable vane meter and weir type of flowmeter.
Paddle Wheel Flow Meter
The paddle wheel flow meter works much as you would think, fluid or gas flows through paddles or cups and spin an impeller. This type of flow meter measures the velocity of a substance and volumetric data can be calculated using these measurements. You will often find paddle wheel flow meters used for irrigation as well as "dirty" water applications.
Vane or Piston Flow Meter
Vane and piston meters are often used for lubricants and corrosive liquids. These flow meters are used in applications with valves, sensors and flow control devices. Often the vane or piston flow meters are used in systems that deliver lubricants to tools.
Gas Flow Meter
Most of the flow meters here can be sued to measure gas flow including steam. You should carefully read product literature before purchasing any flowmeter for any application.
Ultrasonic Flow Meter
This is a volumetric flowmeter that is specifically designed to work with liquids that have particulates in it. This "dirty" water can have a many types of particulates or air bubbles and that the liquid is conductive. The ultrasonic flow meter can be used with clean water by introducing air bubbles upstream of it.
A level sensor measures the level of a substance within a container. There are two types of level sensors. The first type is the continuous level sensor, these operate within a specified range delivering continuous data to your system. The second type is the point value level sensor that checks for a specific level and usually connect to an alarm or flow control system.
Magnetic Flow Meters
These are also called electromagnetic flowmeters as well as induction flowmeter. The liquid being measured must be conductive. There are both insertion and no insertion types of magnetic flow meters and they are normally used to measure flow with waste water as well as other conductive fluids.
Wedge Flow Meter
This is a differential pressure flow measuring device that can be use for nearly any liquids. The wedge type of flow meter is most commonly found in liquids with suspended solids, slurries and viscous fluids
Turbine Flow Meter
Much like the rotameter this device measures the rate of flow as a substance flowed through some type of blades that turn a spindle. There is a direct correlation between the rate of flow and the speed of rotation.
This type of sensor is normally mounted at the top of a tank and measures the distance from it to the substance in the tank. Ultrasonic levels measure distance by bouncing a sound off of the substance and measure that sounds time of travel. It is important to choose an ultrasonic level for the temperature range for its installation.
Positive Displacement Flow Meter
PD meters are made up of a chamber that constricts a portion of liquid flow. This chamber has a known capacity and is fill and emptied repeatedly with each cycle being counted toward the total flow rate. The positive displacement meter can cause a large drop in pressure downstream of its installation.
Mass Flow Meter
Used to measure rate of low for a gas or liquid in units of mass flow such as pounds per minute.
Water Level Sensor
There are many type of water level sensors available including the ultrasonic level sensor described on this page. While most water level sensors can be used with other liquids it is important to note that flammable liquids may prohibit their use.
Portable Ultrasonic Flow Meter
These are ultrasonic flow meters that can be used at any location. The generally clamp around a pipe and work just like the more permanently installed ultrasonic flowmeter.
These articles are only the most basic primer to flow meters and should give enough information to help you search for specific flowmeter topics. Remember that using the right parts to create complex systems is best left engineers but it may be your job to understand what they tell you.