A METER FOR BETTER PERFORMANCE

Introduction:

A flow meter is an instrument used to measure linear, nonlinear, mass or volumetric flow rate of a liquid or a gas. Flow meter applications are very diverse and each situation has its own constraints and engineering requirements. Flow meters are referredto by many names, such as flow gauge, flow indicator, liquid meter, etc. depending on the particular industry; however, the function, to measure flow, remains the same.

Precision in flow meter:

Precision in flow meters are used to provide accurate monitoring and/or flow control. Some industrial applications require precise calculation of quantity, such as precision servo-valve development for the aerospace industry. On the other hand, an application to measure water flow to a vineyard may only require a measurement accuracy of 5% to 10%.

Working principle:

The potential difference is sensed by electrodes aligned perpendicular to the flow and the applied magnetic field. The physical principle at work in flow meter is Faraday's law of electromagnetic induction. The magnetic flow meter requires a conducting fluid and a nonconducting pipe liner.

Pressure & Temperature Ranges

Expected minimum and maximum pressure and temperature values should be given in addition to the normal operating values when selecting flow meters. Whether flow can reverse, whether it does not always fill the pipe, whether slug flow can develop (air-solids-liquid), whether aeration or pulsation is likely, whether sudden temperature changes can occur, or whether special precautions are needed during cleaning and maintenance, these facts, too, should be stated.

Types:

·    Differential Pressure Flow Meters.

·    Positive Displacement Flow Meters.

·    Velocity Flow Meters.

·    Mass Flow Meters.

·    Open Channel Flow Meters.

Unit of measurement:

Before specifying a flow meter, it is also advisable to determine whether the flow information will be more useful if presented in mass or volumetric units. Both gas and liquid flow can be measured in volumetric or mass flow rates, such as litres per second or kilograms per second, respectively. These measurements are related by the material's density. The density of a liquid is almost independent of conditions. This is not the case for gases, the densities of which depend greatly upon pressure, temperature and to a lesser extent, composition.

Other names:

·       Low gauge

·       Flow indicator

·       Liquid meter.

Calibration and methods:

Even though ideally the flow meter should be unaffected by its environment, in practice this is unlikely to be the case. Often measurement errors originate from incorrect installation or other environment dependent factors. methods are used when flow meter is calibrated in the correct flow conditions. The result of a flowmeter calibration will result in two related statistics: a performance indicator metric and a flow rate metric.

·        Transit time method.

·        Tracer dilution method.

Applications of the instrument:

●      Calculating fuel consumption

●      Gas Flow Calculation in Power plants

●      Two component blending

●      On board ships for fuel consumption and power plant monitoring.

Conclusion:

One of the most common flow measurement mistakes is the reversal of this sequence: instead of selecting a sensor which will perform properly, an attempt is made to justify the use of a device because it is less expensive. Those "inexpensive" purchases can be the most costly installations and in turn will lead to reduced efficiency.