Calibration of Flow Sensors by Nabeel Ehmed
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This document discusses different methods for calibrating flow meters, including gravimetric, volumetric, and gas flow meter calibration. Gravimetric calibration of liquid flow meters involves weighing the collected liquid and dividing by density to determine volume. Volumetric calibration uses a container of known volume to collect liquid. Pipe provers provide dynamic volumetric calibration by timing flow between switches of known pipe volume. Gas flow meter calibration uses methods analogous to liquids, commonly using a bell prover which measures displaced air volume into a calibrated bell.
Calibration of Flow Sensors by Nabeel Ehmed
- 3. Flow meters Differential Pressure Meters. Rotary Meters. 1.Displacement 2. Inferential New Flow Meters. 1.Electromagnetic 2.Vortex Shedding 3.Ultrasonic 4.Cross Correlation 5.Tracer 6.Swirl 7.Fluidic Point Velocity Meters. Mass Flow Maters.
- 4. Calibration “The set of oprations that establish, under specified conditions, the relationship between values of quantities indicated by a measuring instrument or measuring system and the corresponding values realized by standards”
- 5. Methods Gravimetric Calibration of Liquid Flow meters Volumetric Calibration of Liquid Flow meters Calibration of Gas Flowmeters
- 6. Gravimetric Calibration of Liquid Flow meters A flow meter can be calibrated gravimetrically by weighing the quantity of liquid collected in a vessel. The vessel is weighed and the weight (in air) of the fluid collected is noted. To determine the volume, the mass is divided by the density determined at the flowmeter Density can be measured using a densitometer but is more often calculated from a knowledge of the fluid properties and measurements of temperature and pressure at the test meter
- 7. Volumetric Calibration of Liquid Flow meters The measurement of the quantity of liquid collected may be carried out volumetrically, that is, by collecting a known volume of liquid in a container. In the volumetric method, the standard vessel takes the form of a container with calibrated volume. Normally, this would be a pipette with conical ends to facilitate drainage and to reduce the risk of air entrapment. The neck of the pipette is normally fitted with a sight glass and a scale marked in volumetric units.
- 8. Volumetric Calibration of Liquid Flow meters Pipe provers provide a dynamic volumetric calibration standard method for calibration. They provide a sealed system providing high-accuracy calibrations in situ as well as in laboratories. A length of pipe is fitted with switches such that the volume between the switches is known. If a displacer, or ‘pig’, is introduced to the flow, the time it takes to travel between the switches will give a measure of the flow rate.
- 9. CALIBRATION OF GAS FLOWMETERS In general, all the methods for the calibration of gas flow meters have analogies with liquid methods. A common standard used extensively for lower pressure calibrations is the ‘ bell prover ’. In this device, air is displaced into a calibrated bell, which rises or lowers as the bell is filled . A bath of oil or water acts asthe seal .