What is doppler move meter?
Doppler flow meter is a sort of ultrasonic circulate meter. These devices use the scientific principle of the Doppler effect to measure the volumetric circulate by way of a pipe. This is completed in such a means that the Doppler circulate meter is clamped to the surface of the pipe, so it does not disturb the circulate as different forms of flow meters require.
Doppler move meters use the frequency of the ultrasonic beam to determine the circulate rate of a liquid. This measurement is feasible because of the Doppler impact discovered by Austrian scientist Christian Johann Doppler within the early 1800s. Essentially, the Doppler impact means that the frequency of a sound wave depends on the motion of the sound receiver, or the source of the sound relative to the medium by way of which the sound travels. In this case, the medium in which the sound wave propagates is the liquid flowing through the pipe.
In order for a Doppler flowmeter to work correctly, the liquid should contain particles or bubbles, so it works properly for soiled liquids, however not so well for clean water. The circulate meter emits an ultrasonic sign, which is mirrored by particles and bubbles, leading to a shift in signal frequency. This frequency shift is measured by the flowmeter.
How does doppler flowmeter work?
The Doppler flowmeter converts the measured frequency shift into a volumetric move rate. The velocity of move in the pipe is calculated utilizing the frequency shift, the original frequency of the ultrasonic signal, the velocity of the sound by way of the emitter materials, and the sine of the angle of the sign into the liquid. Once the speed is understood, the volumetric move fee can be easily calculated by multiplying the velocity by the realm of the pipe.
In calculating the circulate fee, the meter detects the velocity on the discontinuity, not the speed of the fluid. The velocity of move (V) may be determined by the next equation.
V = (f 0 – f 1 )Ct / 2f zero cos(a)
where Ct is the speed of sound contained in the transducer, f0 is the transmission frequency, f1 is the reflection frequency, and a is the angle of the transmitter and receiver crystals with respect to the tube axis. Since C t / 2f 0 cos(a) is a constant (K), the relationship may be simplified to
V = (f 0 – f 1 )K
Thus, the flow fee V (ft/sec) is proportional to the change in frequency. The circulate price (Q in gpm) in a pipe with a specific inside diameter (ID in.) can be obtained by the following equation
Q = 2.45V(ID) 2 = 2.45f 0 -f 1 )K 2
The presence of acoustic discontinuities is critical to the right operation of a Doppler flow meter. The generally accepted rule of thumb is that for proper signal reflection, at least 80-100 mg/l of stable particles are +200 mesh (+75 microns) in size. In the case of bubbles, a diameter of 100-200 mg/l between +75 and +150 microns is right. If the size or concentration of the discontinuity changes, the amplitude of the reflected sign will be shifted, introducing errors.
Doppler flowmeters may have one or two sensors. Both types contain a transmitter and a receiver, but in a single sensor Doppler circulate meter they’re contained in one sensor. Reflected particles in the liquid mirror the transmitted signal again to the receiver. In a dual sensor move meter, the transmitter and receiver are sandwiched on reverse sides of the pipe.
Doppler flow meters can be a good monitoring possibility as a end result of they do not intervene with circulate and require little upkeep. In addition, they will provide fast and correct circulate measurements for a extensive range of liquids beneath a wide range of temperature and circulate conditions. On the opposite hand, liquids should comprise air bubbles or particles for the meter to work correctly, and lined or chrome steel piping can intrude with the transmitter sign and cut back measurement accuracy.
Advantages of Doppler ultrasonic flow meters
Doppler circulate meters can be used the place different meters do not work. This may be liquid slurries, aerated liquids or liquids containing small or large amounts of suspended solids. The advantages could be summarized as follows.
Less obstruction to circulate
Can be installed outside the pipe
Pressure drop equal to the equal length of a straight pipe1
Low move cut-off
Corrosion resistance
Relatively low energy consumption
Extended reading:
Ultrasonic circulate meter working precept
Select the best water circulate meter
Mass flow price vs volumetric circulate fee
Relation between circulate and straine
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What is doppler move meter?
Doppler flow meter is a type of ultrasonic circulate meter. These units use the scientific precept of the Doppler effect to measure the volumetric move via a pipe. This is finished in such a way that the Doppler flow meter is clamped to the surface of the pipe, so it doesn’t disturb the move as other forms of move meters require.
Doppler flow meters use the frequency of the ultrasonic beam to determine the move rate of a liquid. This measurement is feasible because of the Doppler impact found by Austrian scientist Christian Johann Doppler in the early 1800s. Essentially, the Doppler effect means that the frequency of a sound wave depends on the motion of the sound receiver, or the supply of the sound relative to the medium through which the sound travels. In this case, the medium during which the sound wave propagates is the liquid flowing via the pipe.
In order for a Doppler flowmeter to work correctly, the liquid must contain particles or bubbles, so it works nicely for soiled liquids, however not so well for clear water. The move meter emits an ultrasonic signal, which is mirrored by particles and bubbles, resulting in a shift in signal frequency. This frequency shift is measured by the flowmeter.
How does doppler flowmeter work?
The Doppler flowmeter converts the measured frequency shift right into a volumetric flow price. The velocity of circulate in the pipe is calculated using the frequency shift, the unique frequency of the ultrasonic sign, the velocity of the sound by way of the emitter materials, and the sine of the angle of the sign into the liquid. Once the velocity is understood, the volumetric circulate price could be easily calculated by multiplying the rate by the world of the pipe.
In calculating the flow rate, the meter detects the rate on the discontinuity, not the rate of the fluid. The velocity of circulate (V) can be decided by the following equation.
V = (f 0 – f 1 )Ct / 2f zero cos(a)
the place Ct is the velocity of sound contained in the transducer, f0 is the transmission frequency, f1 is the reflection frequency, and a is the angle of the transmitter and receiver crystals with respect to the tube axis. Since C t / 2f zero cos(a) is a constant (K), the connection may be simplified to
V = (f 0 – f 1 )K
Thus, the flow fee V (ft/sec) is proportional to the change in frequency. The move fee (Q in gpm) in a pipe with a specific inner diameter (ID in.) may be obtained by the next equation
Q = 2.45V(ID) 2 = 2.45f 0 -f 1 )K 2
The presence of acoustic discontinuities is crucial to the proper operation of a Doppler circulate meter. The usually accepted rule of thumb is that for proper signal reflection, a minimum of 80-100 mg/l of strong particles are +200 mesh (+75 microns) in dimension. In the case of bubbles, a diameter of 100-200 mg/l between +75 and +150 microns is right. If the dimensions or concentration of the discontinuity changes, the amplitude of the reflected sign might be shifted, introducing errors.
Doppler flowmeters might have one or two sensors. Both varieties comprise a transmitter and a receiver, but in a single sensor Doppler circulate meter they are contained in one sensor. Reflected particles within the liquid reflect the transmitted signal back to the receiver. In ราคาเกจวัดแรงดันลม , the transmitter and receiver are sandwiched on reverse sides of the pipe.
Doppler move meters could be a good monitoring option as a end result of they do not intrude with circulate and require little upkeep. In addition, they’ll provide quick and accurate circulate measurements for a variety of liquids under a wide selection of temperature and circulate situations. On the opposite hand, liquids should contain air bubbles or particles for the meter to work properly, and lined or chrome steel piping can intervene with the transmitter sign and reduce measurement accuracy.
Advantages of Doppler ultrasonic flow meters
Doppler circulate meters can be utilized where other meters do not work. This could additionally be liquid slurries, aerated liquids or liquids containing small or giant quantities of suspended solids. The advantages may be summarized as follows.
Less obstruction to circulate
Can be put in exterior the pipe
Pressure drop equal to the equivalent size of a straight pipe1
Low circulate cut-off
Corrosion resistance
Relatively low power consumption
Extended reading:
Ultrasonic flow meter working principle
Select the right water circulate meter
Mass circulate fee vs volumetric move fee
Relation between move and stresse