Calculations Applied in Using Flow Meters
Technology has revolutionized industries to produce high-end products. In order to produce such products, accuracy and precision in meeting the exact measurements of raw materials is a requirement. This need made the push towards the production of devices for measurement. Flow meters are measuring technologies that enable companies to monitor, measure and calibrate forms of fluids that pass through a pipe.
Flow meter, to measure varied types of fluids in different sets of environments, apply principles and facts to accurately give the volumetric flow rate of a fluid. The following are the calculations applied by flow meters and flow meter users.
Actual to Normalized Flow Conversion – This calculation is concerned with thermal mass, variable area, and vortex flow meters. When such sensors sized and specified for gas flow measurement, the actual flow should be converted to standard flows or normalized flows. As a result, this will determine if a gas flow can be utilized or specified for a given application.
Ideal gas law is the principle behind the said conversion. For the gas flow meter users, they usually need a reference condition in comparing varied flows existing at different conditions in terms of temperature and pressure.
2. Conductivity – Due to its excellent accuracy, low to no pressure loss in the fluid flow, reliability, long service life, and wide turndown ratios, electromagnetic flow meter gains an edge among other types of measuring technology.
The vital part of calibrating and specifying such type of meter is the conductivity of the fluid media used in pipes. Listed are samples of fluid and their conductivity in µS/cm that are compatible and suitable to be measured by electromagnetic flow meters.
Acetic Acid – 318
Zinc Oxide – 2000
Urea – 5000
Starch – 3000
Propionic Acid – 479
Molasses – 300
Latex Paint – 700
Hydrofluoric Acid – 250
Formic Acid – 5500
Corn Syrup – 16
3. Flow Rate to Velocity Conversion – Experts and users of flow meters typically know what flow rate to measure. They calculate and determine if a certain type of flow meter has the capability to measure the volumetric flow based on the published velocity measurement specifications given by the flow meter’s manufacturer.
Differential pressure sensors, magnetic indicator, turbine meter, ultrasonic sensor, and vortex indicator are all flow meter technologies that are specialized to measure the volumetric flow of fluid as a function of fluid velocity. Such measuring technologies will have individually published specifications depending on the range of velocities it can measure.
4. Normalized to Actual Flow Conversion – The actual flow rate is defined as the actual fluid volume passing through a given point in a pipe per unit time or m3/hr. This is deemed a useful measurement to have.
However, the compressibility of gases alters its volume depending on its temperature and pressure. Hence, the gases can be accurately measured if there exists a flow rate referenced to a set temperature and pressure. This is called the standard flow rate or the normal flow rate. This opens up for a comparison of different flows existing at varied flowing conditions in terms of pressure and temperature.
5. Pipe Friction – A fluid passing through a pipe inevitably leads to wall drag or wall friction. This phenomenon causes a decrease in pressure and flow rate. To measure the inviscid and incompressible flow moving from one point to another point along a pipe, Bernoulli’s equation is used.
Bernoulli’s equation explains that the total head that passes through a streamline remains constant. It emphasizes that the head of the velocity can be converted to pressure head and/or gravity head. Hence, the total head remains constant and no energy lost involved in the flow.
6. Reynolds Number – The ratio of forces that are inertial to viscous forces that are enclosed in a fluid is called the Reynolds Number. This ratio is subjected to an internal movement that is relative due to varied velocities of fluids. A flame in air emits hot gases.
These hot gases, in turn, explains a similar effect synthesized from the introduction of a high-velocity fluid stream into a fluid with low velocity. A factor in developing the flow of turbulence is the relative movement of both fluids which generates fluid friction.
8. Velocity to Flow Rate Conversion – This conversion is commonly used when the fluid passes through pipes, ducts, or open channels. This is due to the inconsistency of the fluid’s velocity.
The velocity of the liquid is measured by specialized types of flow meters which are then converted into flow rate by engineers. Through the utilization of the flow continuity equation, engineers will be able to determine the flow range and/or the velocity for any flow-measuring technology.
Precise computations of numbers have shaped the world as it is. The international industrial arena has been dictated by how far can technology go. Knowledge in understanding the calculations made by flow meters and engineers is essential to get an overview of how science and mathematics work together to produce goods and wares necessary for a better living.
Working as a writer and a blogger, Sylvia Hopkins specializes in email marketing campaigns and ghost blogging. Due to her knowledge in liquid flows, she writes about flow measurement instrumentation, flow measurement application, and technology. Sylvia also enjoys the company of her family and friends when not working.