![]() However, in liquids, the effects of fluctuating temperature and pressure are not as critical as in gas flow measurement. Older, early generation flow measurement technologies all made use of volumetric techniques for measuring liquid flow rates. The volume of liquid changes as changes in pressure and temperature occur, while its mass never changes. For measuring a flow: mass flow = volumetric flow (Q) times density(d). For example, the density of air is 1.2 kilograms per cubic meter. Density is commonly expressed in units of grams per cubic centimeter. The formula for density is d = M/V, where d is density, M is mass, and V is volume. An object made from a comparatively dense material (such as iron) will have less volume than an object of equal mass made from some less dense substance (such as water). The average density of an object equals its total mass divided by its total volume. Other factors that affect liquid flow rate include the liquid’s viscosity and density, and the friction of the liquid in contact with the pipe, as well whether a mass flow measurement is better for a given liquid flow application.ĭensity is a measure of mass per unit of volume. This means that the meter output or displayed value on the screen is in volumetric units of measure, such as Gallons Per Minute (GPM), Liters Per Minute (LPM), or one of many other flow units. Q above is volumetric flow rate and volumetric flow meters are the most traditional flow metering technologies. The basic relationship for determining the liquid’s flow rate in such cases is: Because the pipe’s cross-sectional area is known and remains constant, the average velocity is an indication of the flow rate. Velocity depends on the pressure differential that is forcing the liquid through a pipe or conduit. ![]() With most liquid flow meters, the flow rate is determined inferentially by measuring the liquid’s velocity or the change in kinetic energy. SmartmeasurementTM has the most comprehensive selection flow metering technologies, offering our customers a smart solution for their individual application needs. SmartmeasurementTM’s ALCMCoriolis flowmeters offer a perfect solution for mass flow measurement of liquids. Mass flowmeters solve this problem by providing a direct mass flow measurement reading which is immune to changes in process temperature and pressure. The changing density leads to inaccuracy when volumetric meters are applied in these situations. For liquid fluid medias, the density value changes with temperature for gas medias the density changes with both temperature and pressure. Making use of volumetric flowmeters in these applications can prove to be challenging because converting the volumetric units to mass units requires the volumetric reading to multiplied by a media density value. This makes the Coriolis meter an ideal choice for a number of applications that require the flow rate to be measured in mass units, including chemical mixing/batching, custody transfer, and emissions monitoring. Coriolis flow meters are the only type of liquid flow meter that is capable of direct mass flow measurement.
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