Density meter

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Sebuah density meter , juga dikenal sebagai densimeter , adalah perangkat yang mengukur kepadatan. Densitas biasanya disingkat sebagai ${\ displaystyle \ rho}  ÂÂ$ atau ${\ displaystyle D}  ÂÂ$ . Biasanya, kepadatan memiliki satuan ${\ displaystyle kg/m ^ {3}}  ÂÂ$ atau ${\ displaystyle lb/ft ^ {3}}  ÂÂ$ . Prinsip paling mendasar tentang bagaimana densitas dihitung adalah dengan rumus:

${\ displaystyle \ rho = {\ frac {m} {V}}}  ÂÂ$

Dimana:

${\ displaystyle \ rho}  ÂÂ$ = kepadatan sampel.

${\ displaystyle m}  ÂÂ$ = massa sampel.

${\ displaystyle V}  ÂÂ$ = volume sampel.

Many density meters can measure the wet and dry parts of the sample. The wet part comprises the density of all the liquids present in the sample. Dry solids consist only of the solid density present in the sample.

The density density does not directly measure the density of the sample type. However, specific gravity can be deduced from the density measure. Specific gravity is defined as a sample density compared to reference density. Reference density is usually from water. Specific gravity is discovered by the following equation:

Dimana:

${\ displaystyle SG_ {s}}  ÂÂ$ = berat jenis sampel.

${\ displaystyle \ rho _ {s}}  ÂÂ$ = kepadatan sampel yang perlu diukur.

${\ displaystyle \ rho _ {r}}  ÂÂ$ = kepadatan material referensi (biasanya air).

The density meter has many variations. Different types include: nuclear, coriolis, ultrasound, microwave, and gravity. Each type measures the density differently. Each type has its advantages and disadvantages.

The density meter has many applications in different parts of various industries. The meter density is used to measure slurry, mud, and other liquids that flow through the pipes. Industries such as mining, dredging, waste water treatment, paper, oil, and gas all have use for density meters at various points during their respective processes.

Video Density meter

Berbagai jenis Density Meter

Gravimetric

The gravimetric density meter works based on the principle of gravity to calculate sample density. Flexible hoses are used to determine weight changes. By using the fixed two-tail beam deflection principle, weights can be calculated. The increase in weight results in a larger deflection. Weight loss results in a smaller deflection. The volume inside the hose never changes. Because the volume is constant and weighing is known, the density is easily calculated from this information.

The displacement is measured by a high precision lifting laser. The micron scale deflection can be read by the density meter. Small changes in body weight are seen on this scale.

The entire volume is measured using the gravimetric method. This means that the sample size is all of what volume needs to be measured.

Meteran kepadatan Gravimetri menggunakan teori paling sedikit, menjadikannya pilihan yang paling akurat, tergantung pada aplikasinya. Menggunakan persamaan ${\ displaystyle \ rho = {\ frac {m} {V}}}  ÂÂ$ volume diketahui, setelah kami menemukan massanya, kami dapat menemukan kerapatan.

Coriolis

The Coriolis density meter, also known as the mass flow meter or the inertial flow meter, acts on the vibration principle to measure the phase shift in the vibration of a bent, walled tube. The thin, curved walled tube is rotated around the central axis. When there is no mass in the crooked part, the tube remains unrolled. However, as the density inside the hook increases, the inlet portion of the bent pipe drags behind the outflow section. This twisting causes a phase shift which results in a change in the resonance frequency of the thin-walled tube. Therefore, the resonant frequency is directly affected by the density. Higher density media causes a greater Coriolis effect if the volumetric flow rate is constant. The flowing medium causes the frequency and phase shift of the bent pipe, which is proportional to the mass flow rate of the sample.

The Coriolis meter measures the mass flow of the system. They do not measure volumetric flow. However, the volumetric flow can be inferred from the measurement of mass flow. This measurement is limited to the small diameter for the flow tube. However, this measurement technique produces high accuracy and high repeatability. The Coriolis meter also has a fast response time.

Coriolis meters need to be calibrated for temperature and pressure. The zero point for these values ​​is used to calibrate the system. Coriolis meters can not be calibrated while in use. The range difference is used to see how temperature and pressure change.

Nuclear

The nuclear density meter works on the principle of measuring gamma radiation. Gamma radiation is emitted from the source. This source is usually cesium-137 (half-life: ~ 30 years). Radiation is seen by the synthesizer device. Radiation is turned into a flash of light. The number of flashes of light is calculated. The radiation absorbed by the mass is not seen by the synthesizer device. Therefore, the media density is inversely proportional to the radiation captured and seen by the synthesizer.

The nuclear density meter is limited in terms of what the gamma radiation rays see. The sample size is a single, thin column with a small elongated length.

Nuclear equipment requires staff who are certified and licensed to operate the instrument.

Microwave

Microwave density meters have a variety of ways to measure what solids are present in the sample. All microwave meters measure microwaves but some use different methods such as measuring changes in microwave propagation speed, amplitude reduction, flight time, single phase difference, or dual phase shift. Each technique has certain accuracy.

Several microwaves use a ceramic probe that is directly inserted into the sample. This allows the meter to have direct contact to the intended sample. However, this limits the type of slurry and mud that can flow through the pipeline. Abrasive slurries with particulate matter may damage the sensor probe.

Microwave meters are also limited to liquids with unchanged dielectric constant. The percentage of slurry solids affects the dielectric constant for all samples. Typically, a solid percent greater than 20% produces a major error. Similar inconsistencies occur with large pipe diameters.

Microwave meters are excellent at detecting dissolved solids. Homogeneous solutions are easily seen by microwaves. This makes them suitable for applications whose solutions are consistent and not abrasive.

Ultrasonic

The ultrasonic density meter works on various principles to calculate density. One method is the principle of transit time (also known as the flying time principle). In this technique, two transducers are attached to the sides of the pipe wall. The transducer alternates between sending and receiving ultrasonic signals. From this measurement of transit time, the flow velocity and volume flow based on pipe diameter are calculated.

Another method used is the method of ultrasonic attenuation. This method measures the number of different signals with a certain amplitude. The density of media flowing through the pipes affects the signals sent through the pipes. This changes the signal strength, causing weaker signals and smaller amplitude.

Another method used in ultrasonic meters is the average method of envelope energy. This method is not only based on signal amplitude but also signal form. These information packets are called envelopes.

The Doppler ultrasonic meter measures the flow of the suspension in which the concentration of solids in the slurry is above 100ppm and the suspended particles are larger than 100 microns in diameter. However, the Doppler method works only on solids concentrations of less than 10%.

Maps Density meter

Compensation

Temperature

Temperature affects the fluid density. In many cases, an increase in temperature indicates that the media density will decrease. This shows that temperature and density are inversely proportional to each other. Temperature also affects the meter itself. Mass flow meters have different resonant frequencies at different temperatures.

Pressure

Pressure changes the stiffness of the mass flow tube. The pressure affects the gravimetric meter's stiffness.

Vibration

Vibration from plant noise can be filtered. Vibrations seen in microwave, ultrasonic, gravimetric, and Coriolis meters. Vibration causes this type of meter to accumulate errors

Damage

Coriolis meters have compensation from pitting, cracking, coating, erosion, and corrosion. This damage affects the way the tubes resonate. This change affects the baseline. Compensation can not be created dynamically. This damage usually causes offsets that can be added to existing calibration factors which will ensure a consistent reading is still obtained.

src: koehlerinstrument.com

References

Source of the article : Wikipedia