Engineering 101: Let’s Talk About Flow Meters

A flow meter is an instrument used by professionals to measure the flow rate of gas or liquid. When choosing flow meters, one should consider such imperceptible factors in terms of the familiarity with the plant personnel, the experience they have in calibration and maintenance, and the like. Moreover, it is highly recommended that the cost of the process be computed after installation. 

Keep in mind that one of the most common flow measurement mistakes is instead of selecting a meter that performs properly, some make attempts to use devices that are not in line with the process because it is less expensive. But those “inexpensive” purchases can turn out to be the costliest installations. If the process requires you to use an electronic flow meter, then use it rather than sorting to options that may potentially lead to a problem.

Below, we will help you understand flow meters better as well as give substantial knowledge you can apply anytime if you have any special flow measurement problem.

Choosing the Right Flow Meter

The first step in selecting a suitable flow meter is to determine if the flowrate information should be continuous or in totality and whether the information is needed locally or remotely. In addition, consider these: If info is needed remotely, does the transmission have to be in analog, digital, or shared format? And, if it is shared, do not forget the required data-update frequency. Once determined, an evaluation of the properties and flow characteristics of the process fluid should proceed.

Fluid and flow characteristics

The fluid — along with its given pressure, temperature, and all essential elements and factors to consider — must be listed, together with an indication of how these properties differ or interact. In addition, all safety or toxicity information should be provided together with detailed data on the fluid’s composition.

Piping and Area of Installation

There are things to consider concerning the piping and the area where the flowmeters are to be installed. First, for the piping, avoid downward flow in liquid applications. Consider as well the size, material, accessibility, valves, regulators, and available straight-pipe run lengths. Your engineers must know if the occurrence of vibration or magnetic fields are present in the area, if the area is classified for explosion hazards, or if there are other special requirements such as compliance with sanitary and city safety regulations.

Flow rates and Accuracy

The next step is to determine the required meter range by identifying minimum and maximum flows. Then, the required flow measurement accuracy is determined. Normally, accuracy is identified in the percentage of actual reading, in the percentage of the calibrated span, or in full-scale units. The accuracy requirements should be separately stated at normal, minimum, and maximum flow rates. Unless you know these requirements, your flowmeter’s performance may not be acceptable over its full range.

Moreover, in actual applications where products are sold or purchased on the basis of a meter reading, accuracy is vital. In other applications, repeatability may be more important than total accuracy. Therefore, it is recommended to establish the accuracy and repeatability requirements of each application separately.

Every procedure must be handled with care and performed tediously. Furthermore, compromising accuracy for lower costs can lead to issues that may necessitate higher expenses.