Flow Meter Advantages and Disadvantages

10/19/2017

There are different kinds of flow meters from different suppliers and manufacturers in the market or on the internet. Each kind of these flow meters have different types of functions from size and type of flow being measured, i.e. water quality measurements. There are also advantages and disadvantages of different kinds of flow meters which is discussed below.

Electromagnetic flow meters have unobstructed flow passage without projecting parts which are safely used in water flow measurements and in places where there are a lot of traffic. There are also no moving parts which is advantageous if used in energy saving equipment. It has no additional pressure drop which allows a more accurate measurement of the flow. Essentially, it is flow profile insensitive which allows only short inlet and outlet sections. It is unaffected by changes in temperature, density, viscosity, concentration and electrical conductivity. It is a favored choice for materials which are chemically aggressive or abrasive in measuring media. It is also unaffected by contamination and deposits which is especially suitable for hydraulic solids transport. There is a linear relationship between flow rate and measured variable which operates in both flow directions (forward and revers). The measuring range of this flow meter can be optimized in the settings, low maintenance and very easy to maintain. The only limitations of this flow meter is that it is used for fluids only, lower conductivity limit at 0.05 uS/cm and has gas inclusions that causes errors.

Ultrasonic flow meters also have unobstructed flow passage and moving parts therefore, has no additional pressure drop for efficient measurement of flow. Chemically aggressive liquids are the favorable choice of materials. It also has linear relationship between flow rate and measured variable. It has low maintenance and operates in both flow directions. Transit time meters are unaffected by temperature, density and concentration. Later installation in existing pipes is possible with individual elements, but on site calibration is required. The limitations of this flow meter include errors due to deposits. It is till problematic for liquid and gas measurements. Sound beams must traverse a representative cross section, therefore it is flow profile dependent which requires long inlet and outlet sections. Its transit time meters require clean liquids. The Doppler meters are only for slight contamination or a few gas bubbles. Doppler meters affected by the sound velocity changes due to temperature, density and concentration. It is unsuitable for heavily contaminated liquids and that it is easily affected by gas bubbles that causes errors in the reading of flow measurement.

The Coriolis mass flow meters have true mass flow measurements. It has additional temperature and density measurements which are high accuracy for mass flow measurements. It can also accurately measure density and is unaffected by pressure, temperature and viscosity. There are also no inlet and outlet sections required which operates in both flow directions. Its measuring range settings can be optimized for flow rate and density which has a self-draining ability. Its limitations are: it is affected by gas inclusions and vibration sensitive when improperly installed.