Flowmeter

Flowmeter

A flowmeter is used to measure the linear, nonlinear, mass or volumetric flow rate of a liquid or a gas. The intangible factors when choosing flowmeters are familiarity with plant personnel, experience with calibration and maintenance, spare parts availability and mean time between failure etc. Common mistakes when selecting a flow meter is instead of selecting a sensor that will perform properly, they tend to select a less-expensive sensor and then justify the use of the device. But those “inexpensive” selection can be the costliest installations.

Measurement of flow meter can be done as follow:

Flow(Q) = Cross-sectional area of pipe(A) * Velocity of flowing fluid(v)

Mass Flow(m) = Volumetric flow rate (Q) * Fluid Density (p)

Steps to choose the right flow meter:

• Determine the flowrate information should be continuous or totalized
• Information needed locally or remotely
  • If remotely, transmission be analog, digital, or shared?
    • If shared, what is the required (minimum) data-update frequency?
• Evaluation of the properties and flow characteristics of the process fluid, and the piping that will accommodate the flow meter.
• Costly products that need precise measurement?
• Liquid, gas or steam?
• Very large flows or small flows only?
• Low pressure/High pressure of liquid, gas or steam?
• Liquid, gas, or steam flowing in complicated or big piping arrangements?

There are multiple types of flowmeters. The first type of flow meter is the capillary thermal mass flow meter. It uses the thermal heat transferred between gas passing through a very small tube (the capillary) and a set of resistance temperature detectors (RTDs) to measure the mass flow of gas. The second type of flow meter is the Immersible thermal mass flow meter. It uses the thermal heat transferred from a heated sensor immersed in the flow to measure the mass flows of the gas. The third type of flow meter is the vortex shedding flow meter. It measures the mass and/or volumetric flow of liquids, gases, and steam using vortices shed from a sensor immersed in the flow and a computer fluid density.

The fourth type of flow meter is Transit-Time Ultrasonic flow meter. It measures the speed of fluid passing through a pipe using ultrasound and can be fitted onto the outside of the pipe, thus eliminating the need for pipe cutting. It is a clamp-on system, installed from outside the pipe for completely non-wetted measurement, preventing any risk of adverse effects on the liquid and eliminating the need for piping work. The fifth type of flow meter is the Electromagnetic flow meter. It detects the flow via electromotive force created through electromagnetic induction.

The sixth type of flow meter is the Paddlewheel flow meter. When fluid flowing through the pipe instigates the spinning of the paddlewheel. Magnets in the paddle spin past the sensor. The electrical pulses produced are proportional to the rate of flow. The seventh type of flow meter is the floating element flow meter. A float is suspending in a tapered pipe (the pipe that progressively widens heading upwards). When fluid is forced in between the tapered pipe and the float, a differential pressure is generated. When this happens, the float stops at an area where the upward force caused by differential pressure and the downward force caused by the weight of the float that has been equalized. The resulting display is the instantaneous flow. The seventh type of flow meter is the diaphragm flow meter. An orifice plate is installed into the path of the following fluid, deliberately causing pressure loss. The pressure differential before and after the orifice plate is measured. The smaller flow, the smaller the flow velocity, the smaller pressure loss created by the orifice.

Different type of flow meter is suited with different situation. Vortex shedding flow meter is suited for measuring the flow of liquids and steam at high temperature and pressures. Thermal mass flow meters on the other hand are suited for the mass flow of gases from low to high flows. Transit-Time Ultrasonic flow meters are suited for measuring the flow of meter or other liquids when no process shutdown or pipe cutting is ideal.

Flow meter possesses many benefits for the user. Firstly, the flow meter is able to be used for quality control where it can monitor liquid passed through. The information is then managed/analysed accordingly to improve or stabilize product quality. Secondly, a flow meter also enables predictive maintenance and superior device protection. It prevents any deterioration inequality or malfunctions with equipment due to improper cooling. Besides the quick detection of a decrease in flow rate makes it possible to immediately perform predictive maintenance to avoid adverse effects on production or equipment. Lastly, the amounts of resources used are able to be visualized to conserve energy which reduces costs with that information the instantaneous and total flow rates can be managed simultaneously to detect abnormal flows.

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Flowmeters are available through Quick Time Engineering Inc.

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Quick Time Engineering Inc is an international company with offices and distribution networks in the USA, Hong Kong, Europe and Malaysia.

In its 20 years of operation since 1998, Quick Time Engineering Inc had emerged from a local engineering company with a single staff that provided solutions in factory automation to become nowadays a company that serves the Oil & Gas industries, EPC contractors, System Integrators and other industrial automation and process control companies worldwide. Customers from over 50 countries worldwide trust us with their need for process control instruments and industrial automation products.

For more information about Quick Time Engineering Inc, visit www.quicktimeonline.com or email enquiry@quicktimeonline.com