Which Flow meter Is Best for Your Application?

From single-use to magnetic to variable-area, the options in flow meters are plentiful. But there are distinct differences in functionality, accuracy, and certainly price. Ultrasonic sensors that accurately and non-invasively measure through commonly used tubing is an excellent multi-use option that is positioned on the higher end of the price scale. If low unit price is desirable without sacrificing accuracy, then single-use turbine type sensors are a good option particularly if working fluid is low viscosity. If higher viscosity working fluids are involved, the single-use flow through disposable ultrasonic sensors are the best fit.

When selecting a flow meter consideration must be given to:

304 stainless steel flow measurement type - momentum (velocity), volumetric or mass flow measurement

Accuracy - required accuracy of the readings

Media - type of media (liquid, gas or slurry) and any special condition such as particulates in the media and viscosity of the media

Media conditions - pressure and temperature of media and whether media conditions are likely to remain constant or vary

Flow range - required flow range of media (min and max readings required)

Here is the flowmeter options available to you:

Electromagnetic flow meter advantages and disadvantages (or magmeters) are available in two design styles: insertion and full-bore. Coils in the meter produce a magnetic field. When a conductive fluid is passed through the field, a voltage is produced through an electrode in the meter wall or insertion probe; this generated voltage is proportional to the flow. Magmeters operate by measuring the electrical content of water or other fluids. The magnetic technology contains no moving parts, and the full-bore designs offer no intrusions into the flow stream. Magmeters are higher-end flow meters and are used in the food & beverage industry, water purification, pulp and paper manufacturing, mining, chemical manufacturing, and petrochemical industries. They should not be used with low conductivity fluids such as de-ionized water.

Turbine meters contain a bladed rotor positioned along the centerline of the flow stream. The rotating component is designed to provide a pulse when passing either a magnetic or optical sensor. The frequency of the pulses is proportional to the velocity of the fluid. Some designs offer high levels of accuracy and can handle slightly higher viscosity fluids than basic propeller-type designs. Also, some turbine designs meet sanitary guidelines.

Ultrasonic meters offer more advanced technology and greater versatility than some other types. These designs measure the frequency shift of an ultrasonic signal that is sent through the fluid. Two types of ultrasonic meters are Doppler and transit-time. Doppler technologies utilize particles or aeration in the fluid as a reflective mechanism to gauge the velocity of the fluid. Transit-time technologies rely on a frequency difference in forward and reverse signals sent though a clean liquid to gauge the velocity of the fluid; the fluid must not have solids or aeration, as they will distort the sonic pulses. These are ideal technologies to create flow profiles through an existing process, when modifying piping is not possible.

Ultrasonic flow meters are used in a long list of industries, including facilities management, pulp and paper manufacturing, chemical manufacturing, and mining. Water/wastewater, petrochemical, and aquafarms also enlist this technology. Ultrasonic meters can be used to measure the corrosiveness of slurry fluid flow.

Vortex meters use a pressure sensor to measure the pressure pulses from vortices that come from the fluid passing a bluff body bar across the flow stream. A simple analogy of this phenomenon is that of a flag waving in the wind. The pulses are proportional to the rate of flow. Many users find the technology appealing because it has no moving parts