445:
plastic bowl in a microwave oven). They are also largely unaffected by high temperature, pressure, vacuum or vibration. As these sensors do not require physical contact with the process material, so the transmitter /receiver can be mounted a safe distance above/from the process, even with an antenna extension of several meters to reduce temperature, yet still respond to the changes in level or distance changes e.g. they are ideal for measurement of molten metal products at over 1200 °C. Microwave transmitters also offer the same key advantage of ultrasonics: the presence of a microprocessor to process the signal, provide numerous monitoring, controls, communications, setup and diagnostic capabilities and are independent of changing density, viscosity and electrical properties. Additionally, they solve some of the application limitations of ultrasonics: operation in high pressure and vacuum, high temperatures, dust, temperature and vapor layers. Guided wave radars can measure in narrow confined spaces very successfully, as the guide element ensures correct transmission to and from the measured liquid. Applications such as inside stilling tubes or external bridles or cages, offer an excellent alternative to float or displacement devices, as they remove any moving parts or linkages and are unaffected by density changes or build up. They are also excellent with very low microwave reflectivity products like liquid gasses (LNG, LPG, ammonia) which are stored at low temperatures/high pressures, although care needs to be taken on sealing arrangements and hazardous area approvals. On bulk solids and powders, GWR offers a great alternative to radar or ultrasonic sensors, but some care needs to be taken over cable wear and roof loading by the product movement.
441:
of light divided by the square root of the dielectric constant of the medium ), similar to ultrasonic level sensors, and
Doppler systems employing FMCW techniques. Just as with ultrasonic level sensors, microwave sensors are executed at various frequencies, from 1 GHz to 60 GHz. Generally, the higher the frequency, the more accurate, and the more costly. Microwave is executed non-contact technique or guided. The first is done by monitoring a microwave signal that is transmitted through free space (including vacuum) and reflected back, or can be executed as a "radar on a wire" technique, generally known as guided wave radar or guided microwave radar. In the latter technique, performance generally improves in powders and low dielectric media that are not good reflectors of electromagnetic energy transmitted through a void (as in non-contact microwave sensors). This technique can use application specific waveguides to get more accurate results or additional information required for sensor application (e.g. some sensors can use tank parts or other equipment as a waveguide or its part). It's common practice to use remote waveguides, when waveguide is distanced from electronic part (commonly for reservoirs with harsh conditions, radiation, or boiling under high pressure liquids/gases, etc.). But with the guided technique the same mechanical constraints exist that cause problems for the capacitance (RF) techniques mentioned previously by having a probe in the vessel.
374:
systems have sufficiently "intelligent" echo processing to make engineering changes largely unnecessary except where an intrusion blocks the line of sight of the transducer to the target. Since the ultrasonic transducer is used both for transmitting and receiving the acoustic energy, it is subject to a period of mechanical vibration known as "ringing". This vibration must attenuate (stop) before the echoed signal can be processed. The net result is a distance from the face of the transducer that is blind and cannot detect an object. It is known as the "blanking zone", typically 150 mm to 1 m, depending on the range of the transducer.
348:
289:. These sensors are suitable for use with highly viscous liquids such as grease, as well as water-based and corrosive liquids. This has the additional benefit of being a relatively low cost technique for point level monitoring. A variation of this technique is the "bubbler", which compresses air into a tube to the bottom of the tank, until the pressure increase halts as the air pressure gets high enough to expel air bubbles from the bottom of the tube, overcoming the pressure there. The measurement of the stabilized air pressure indicates the pressure at the bottom of the tank, and, hence, the mass of fluid above.
301:, nitric acid, ferric chloride, and similar liquids. For those conductive liquids that are corrosive, the sensor's electrodes need to be constructed from titanium, Hastelloy B or C, or 316 stainless steel and insulated with spacers, separators or holders of ceramic, polyethylene and Teflon-based materials. Depending on their design, multiple electrodes of differing lengths can be used with one holder. Since corrosive liquids become more aggressive as temperature and pressure increase, these extreme conditions need to be considered when specifying these sensors.
548:, can be suspended from a cable into the tank to the bottom point that is to be measured. The sensor must be specially designed to seal the electronics from the liquid environment. In tanks with a small head pressure (less than 100 INWC), it is very important to vent the back of the sensor gauge to atmospheric pressure. Otherwise, normal changes in barometric pressure will introduce large error in the sensor output signal. In addition, most sensors need to be compensated for temperature changes in the fluid.
136:, physical size and mounting of the instrument, monitoring or control of continuous or discrete (point) levels. In short, level sensors are one of the very important sensors and play very important role in a variety of consumer/ industrial applications. As with other types of sensors, level sensors are available or can be designed using a variety of sensing principles. Selection of an appropriate type of sensor suiting to the application requirement is very important.
496:
897:, or water with large quantities of suspended solids. The only part of the sensor that contacts the liquid is a bubble tube which is chemically compatible with the material whose level is to be measured. Since the point of measurement has no electrical components, the technique is a good choice for classified hazardous areas. The control portion of the system can be located safely away, with the pneumatic plumbing isolating the hazardous from the safe area.
437:
ultrasonic. Microwaves are electromagnetic energy and therefore do not require air molecules to transmit the energy making them useful in vacuums. Microwaves, as electromagnetic energy, are reflected by objects with high conductive properties, like metal and conductive water. Alternately, they are absorbed in various degrees by 'low dielectric' or insulating mediums such as plastics, glass, paper, many powders and food stuffs and other solids.
261:
mechanical float level sensors, chemical compatibility, temperature, specific gravity (density), buoyancy, and viscosity affect the selection of the stem and the float. For example, larger floats may be used with liquids with specific gravities as low as 0.5 while still maintaining buoyancy. The choice of float material is also influenced by temperature-induced changes in specific gravity and viscosity – changes that directly affect buoyancy.
276:" sensor which utilizes the magnetic sensing of a mechanical gauge's indications. In a typical application, a magnetism-sensitive "Hall effect sensor" is affixed to a mechanical tank gauge that has a magnetized indicator needle, so as to detect the indicating position of the gauge's needle. The magnetic sensor translates the indicator needle position into an electrical signal, allowing other (usually remote) indication or signalling.
313:. Conductive probes have the additional benefit of being solid-state devices and are very simple to install and use. In some liquids and applications, maintenance can be an issue. The probe must continue to be conductive. If buildup insulates the probe from the medium, it will stop working properly. A simple inspection of the probe will require an ohmmeter connected across the suspect probe and the ground reference.
305:
incorporates some aspect of control, such as high-low or alternating pump control. A conductive liquid contacting both the longest probe (common) and a shorter probe (return) completes a conductive circuit. Conductive sensors are extremely safe because they use low voltages and currents. Since the current and voltage used is inherently small, for personal safety reasons, the technique is also capable of being made
169:
201:
mounted on the motor contacts a mechanical switch. The paddle can be constructed from a variety of materials, but tacky material must not be allowed to build up on the paddle. Build-up may occur if the process material becomes tacky because of high moisture levels or high ambient humidity in the hopper. For materials with very low weight per unit volume such as
507:
The field compass location provides a physical location of the float position. The choice of float and stem materials depends on the liquid in terms of chemical compatibility as well as specific gravity and other factors that affect buoyancy of the float. The electronic monitoring system does not come in contact with the fluid and is considered
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there is also the capability for serial communication from to other computing devices making this a good technique for adjusting calibration and filtering of the sensor signal, remote wireless monitoring or plant network communications. The ultrasonic sensor enjoys wide popularity due to the powerful mix of low price and high functionality.
225:. The probe is driven through a shielded coaxial cable to eliminate the effects of changing cable capacitance to ground. When the level changes around the probe, a corresponding change in the dielectric is observed. This changes the admittance of this imperfect capacitor and this change is measured to detect change of level.
192:
Vibrating level sensors are not affected by dust, static charge build-up from dielectric powders, or changes in conductivity, temperature, pressure, humidity or moisture content. Tuning-fork style vibration sensors are another alternative. They tend to be less costly, but are prone to material buildup between the tines,
265:
with the materials used to construct the sensor. Float-style sensors should not be used with high viscosity (thick) liquids, sludge or liquids that adhere to the stem or floats, or materials that contain contaminants such as metal chips; other sensing technologies are better suited for these applications.
577:
Hydrostatic pressure, also gravity pressure or gravity pressure, occurs within a stationary fluid. It is caused by gravity and depends on the density and height of the liquid column. The mass of the fluid does not matter - see also hydrostatic paradox - i. e. not the total weight of the liquid in the
568:
For deep well designs, the Sealed Gauge measuring principle is also used. From a depth of approx. 20 m, the relative pressure can only be compensated to a limited extent by the thin hose. The level sensor is then designed as an absolute pressure transmitter whose zero point is adjusted to the desired
560:
of the liquid column causes an expansion of the pressure-sensitive sensor element, which converts the measured pressure into an electrical standard signal. The connecting cable of level probes has several tasks to fulfil. In addition to the power supply and signal forwarding, the level sensor is held
444:
Non contact microwave-based radar sensors are able to see through low conductivity 'microwave-transparent' (non-conductive) glass/plastic windows or vessel walls through which the microwave beam can be passed and measure a 'microwave reflective' (conductive) liquid inside (in the same way as to use a
427:
An alternate approach for continuous optical level sensing involves the use of a laser. Laser light is more concentrated and therefore is more capable of penetrating dusty or steamy environments. Laser light will reflect off most solid, liquid surfaces. The time of flight can be measured with precise
423:
A common application of economical infrared-based optical interface point level sensors is detecting the sludge/water interface in settling ponds. By using pulse modulation techniques and a high power infrared diode, one can eliminate interference from ambient light, operate the LED at a higher gain,
398:
as low as 1.1 (coke and fly ash) and as high as 88 (water) or more. Sludges and slurries such as dehydrated cake and sewage slurry (dielectric constant approx. 50) and liquid chemicals such as quicklime (dielectric constant approx. 90) can also be sensed. Dual-probe capacitance level sensors can also
333:
The microprocessor in a state dependent frequency monitor can actuate valves and/or large pumps with very low power consumption. Multiple switch controls can be built in to small package while providing complex, application specific functionality using the microprocessor. Low power consumption of the
828:
The measuring minimum level starts from a complete covering of the measuring element near the head end of the level sensor. Filling levels below the level probe are not detected. Depending on the application and mounting height, it is therefore necessary to adjust the level in the evaluation unit to
536:
suitable for measuring the level of corrosive liquids in deep tanks or water in reservoirs. Typically, fluid level is determined by the pressure at the bottom of the fluid containment (tank or reservoir); the pressure at the bottom, adjusted for the density / specific gravity of the fluid, indicates
486:
The choice of float and stem materials depends on the liquid in terms of chemical compatibility as well as specific gravity and other factors that affect buoyancy. These sensors work well for liquid level measurements in marine, chemical processing, pharmaceuticals, food processing, waste treatment,
465:
level sensors are similar to float type sensors in that a permanent magnet sealed inside a float travels up and down a stem in which a magnetostrictive wire is sealed. Ideal for high-accuracy, continuous level measurement of a wide variety of liquids in storage and shipping containers, these sensors
419:
Optical sensors are used for point level sensing of sediments, liquids with suspended solids, and liquid-liquid interfaces. These sensors sense the decrease or change in transmission of infrared light emitted from an infrared diode (LED). With the proper choice of construction materials and mounting
329:
A strength of state dependent frequency monitoring is long term stability of the sensing probes. The signal strength is not sufficient to cause fouling, degradation, or deterioration of the sensors due to electrolysis in contaminated water. Sensor cleaning requirements are minimal or eliminated. Use
256:
The principle behind magnetic, mechanical, cable, and other float level sensors often involves the opening or closing of a mechanical switch, either through direct contact with the switch, or magnetic operation of a reed. In other instances, such as magnetostrictive sensors, continuous monitoring is
900:
Air bubbler systems are a good choice for open tanks at atmospheric pressure and can be built so that high-pressure air is routed through a bypass valve to dislodge solids that may clog the bubble tube. The technique is inherently self-cleaning. It is highly recommended for liquid level measurement
506:
float level sensors are similar to float level sensors however a permanent magnet pair is sealed inside the float arm pivot. As the float moves up the motion and location are transmitted as the angular position of the magnetic field. This detection system is highly accurate down to 0.02° of motion.
469:
Magnetostrictive level and position devices charge the magnetostrictive wire with electric current, when the field intersects the floats' magnetic field a mechanical twist or pulse is generated, this travels back down the wire at the speed of sound, like ultrasound or radar the distance is measured
440:
Microwave sensors are executed in a wide variety of techniques. Two basic signal processing techniques are applied, each offering its own advantages: pulsed or time-domain reflectometry (TDR) which is a measurement of time of flight divided by the speed of electromagnetic waves in the medium (speed
377:
The requirement for electronic signal processing circuitry can be used to make the ultrasonic sensor an intelligent device. Ultrasonic sensors can be designed to provide point level control, continuous monitoring or both. Due to the presence of a microprocessor and relatively low power consumption,
358:
level sensors are used for non-contact level sensing of highly viscous liquids, as well as bulk solids. They are also widely used in water treatment applications for pump control and open channel flow measurement. The sensors emit high frequency (20 kHz to 200 kHz) acoustic waves that are
325:
A microprocessor controlled frequency state change detection method uses a low amplitude signal generated on multiple sensor probes of differing lengths. Each probe has a frequency separate from all other probes in the array and independently changes state when touched by water. The state change of
268:
A special application of float-type sensors is the determination of interface level in oil-water separation systems. Two floats can be used with each float sized to match the specific gravity of the oil on one hand, and the water on the other. Another special application of a stem type float switch
264:
Float-type sensors can be designed so that a shield protects the float itself from turbulence and wave motion. Float sensors operate well in a wide variety of liquids, including corrosives. When used for organic solvents, however, one will need to verify that these liquids are chemically compatible
402:
Since capacitance level sensors are electronic devices, phase modulation and the use of higher frequencies makes the sensor suitable for applications in which dielectric constants are similar. The sensor contains no moving parts, is rugged, simple to use, and easy to clean, and can be designed for
369:
Turbulence, foam, steam, chemical mists (vapors), and changes in the concentration of the process material also affect the ultrasonic sensor's response. Turbulence and foam prevent the sound wave from being properly reflected to the sensor; steam and chemical mists and vapors distort or absorb the
482:
Resistive chain level sensors are similar to magnetic float level sensors in that a permanent magnet sealed inside a float moves up and down a stem in which closely spaced switches and resistors are sealed. When the switches are closed, the resistance is summed and converted to current or voltage
410:
A significant limitation for capacitance probes is in tall bins used for storing bulk solids. The requirement for a conductive probe that extends to the bottom of the measured range is problematic. Long conductive cable probes (20 to 50 meters long), suspended into the bin or silo, are subject to
304:
Conductive level sensors use a low-voltage, current-limited power source applied across separate electrodes. The power supply is matched to the conductivity of the liquid, with higher voltage versions designed to operate in less conductive (higher resistance) mediums. The power source frequently
284:
Pneumatic level sensors are used where hazardous conditions exist, where there is no electric power or its use is restricted, or in applications involving heavy sludge or slurry. As the compression of a column of air against a diaphragm is used to actuate a switch, no process liquid contacts the
80:
whereas most bulk solids pile at an angle of repose to a peak. The substance to be measured can be inside a container or can be in its natural form (e.g., a river or a lake). The level measurement can be either continuous or point values. Continuous level sensors measure level within a specified
540:
Since these sensors sense increasing pressure with depth and because the specific gravities of liquids are different, the sensor must be properly calibrated for each application. In addition, large variations in temperature cause changes in specific gravity that should be accounted for when the
473:
Because of the accuracy possible with the magnetostrictive technique, it is popular for "custody-transfer" applications. It can be permitted by an agency of weights and measures for conducting commercial transactions. It is also frequently applied on magnetic sight gages. In this variation, the
373:
Proper mounting of the transducer is required to ensure the best response to reflected sound. In addition, the hopper, bin, or tank should be relatively free of obstacles such as weldments, brackets, or ladders to minimise false returns and the resulting erroneous response, although most modern
564:
Without this so-called relative pressure compensation, level probes would not only measure the hydrostatic pressure but also the air pressure on the liquid column. At sea level, this is about 1013 mbar - which would correspond to the pressure exerted by a water column ten meters high. In
436:
Microwave sensors are ideal for use in moist, vaporous, and dusty environments as well as in applications in which temperatures and pressures vary. Microwaves (also frequently described as radar), will penetrate temperature and vapor layers that may cause problems for other techniques, such as
406:
Appropriate choice of probe materials reduces or eliminates problems caused by abrasion and corrosion. Point level sensing of adhesives and high-viscosity materials such as oil and grease can result in the build-up of material on the probe; however, this can be minimized by using a self-tuning
233:
Typical systems for point level detection in liquids include magnetic and mechanical floats, pressure sensors, electroconductive sensing or electrostatic (capacitance or inductance) detectors—and by measurement of a signal's time-of-flight to the fluid surface, through electromagnetic (such as
200:
Rotating paddle level sensors are a very old and established technique for bulk solid point level indication. The technique uses a low-speed gear motor that rotates a paddle wheel. When the paddle is stalled by solid materials, the motor is rotated on its shaft by its own torque until a flange
260:
With magnetically actuated float sensors, switching occurs when a permanent magnet sealed inside a float rises or falls to the actuation level. With a mechanically actuated float, switching occurs as a result of the movement of a float against a miniature (micro) switch. For both magnetic and
191:
Single-probe vibrating level sensors are ideal for bulk powder level. Since only one sensing element contacts the powder, bridging between two probe elements is eliminated and media build-up is minimized. The vibration of the probe tends to eliminate build-up of material on the probe element.
448:
One perceived major disadvantage of microwave or radar techniques for level monitoring is the relatively high price of such sensors and complex set up. However, price has reduced significantly over the last few years, to match those of longer range ultrasonics, with simplified set up of both
393:
Capacitance level sensors excel in sensing the presence of a wide variety of solids, aqueous and organic liquids, and slurries. The technique is frequently referred to as RF for the radio frequency signals applied to the capacitance circuit. The sensors can be designed to sense material with
561:
in place by the cable. The cable also includes a thin air tube that directs the ambient air pressure to the level probe. Level probes are therefore usually designed as relative pressure sensors, which use the current ambient pressure as the zero point of their measuring range.
929:
on the other. As the level of molten steel rises in the mold, less of the gamma radiation is detected by the sensor. The technique allows non-contact measurement where the heat of the molten metal makes contact techniques and even many non-contact techniques impractical.
569:
mean air pressure depending on the location of use. This means that the level sensor no longer has any connection to the atmosphere. Possible fluctuations in air pressure may have an impact on the measurement result, but they play a rather minor role in deep well wells.
316:
Typically, in most water and wastewater wells, the well itself with its ladders, pumps and other metal installations, provides a ground return. However, in chemical tanks, and other non-grounded wells, the installer must supply a ground return, typically an earth rod.
487:
and other applications. With the proper choice of two floats, resistive chain level sensors can also be used to monitor for the presence of an interface between two immiscible liquids whose specific gravities are more than 0.6, but differ by as little as 0.1 unit.
403:
high temperature and pressure applications. A danger exists from build-up and discharge of a high-voltage static charge that results from the rubbing and movement of low dielectric materials, but this danger can be eliminated with proper design and grounding.
474:
magnet is installed in a float that travels inside a gage glass or tube. The magnet operates on the sensor which is mounted externally on the gage. Boilers and other high temperature or pressure applications take advantage of this performance quality
428:
timing circuitry, to determine the range or distance of the surface from the sensor. Lasers remain limited in use in industrial applications due to cost, and concern for maintenance. The optics must be frequently cleaned to maintain performance.
901:
applications where ultrasonic, float or microwave techniques have proved undependable. The system will require constant supply of air during measurement. The end of the tube should be above certain height to avoid sludge from clogging the tube.
514:
Due to the presence of a microprocessor and low power consumption, there is also capability for serial communication from to other computing devices making this a good technique for adjusting calibration and filtering of the sensor signal.
466:
require the proper choice of float based on the specific gravity of the liquid. When choosing float and stem materials for magnetostrictive level sensors, the same guidelines described for magnetic and mechanical float level sensors apply.
81:
range and determine the exact amount of substance in a certain place, while point-level sensors only indicate whether the substance is above or below the sensing point. Generally the latter detect levels that are excessively high or low.
399:
be used to sense the interface between two immiscible liquids with substantially different dielectric constants, providing a solid state alternative to the aforementioned magnetic float switch for the "oil-water interface" application.
889:
level sensor uses a tube with an opening below the surface of the liquid level. A fixed flow of air is passed through the tube. Pressure in the tube is proportional to the depth (and density) of the liquid over the outlet of the tube.
213:, special paddle designs and low-torque motors are used. Fine particles or dust must be prevented from penetrating the shaft bearings and motor by proper placement of the paddle in the hopper or bin and using appropriate seals.
370:
sound wave; and variations in concentration cause changes in the amount of energy in the sound wave that is reflected back to the sensor. Stilling wells and waveguides are used to prevent errors caused by these factors.
541:
pressure is converted to level. These sensors can be designed to keep the diaphragm free of contamination or build-up, thus ensuring proper operation and accurate hydrostatic pressure level measurements.
511:
or explosion proof. These sensors work well for liquid level measurements in marine, vehicle, aviation, chemical processing, pharmaceuticals, food processing, waste treatment, and other applications.
84:
There are many physical and application variables that affect the selection of the optimal level monitoring method for industrial and commercial processes. The selection criteria include the physical:
297:
Conductive level sensors are ideal for the point level detection of a wide range of conductive liquids such as water, and is especially well suited for highly corrosive liquids such as caustic soda,
556:
Pressure level probes are submerged directly into the liquid and remain permanently floating above the tank bottom. The measurement is carried out according to the hydrostatic principle. The
537:
the depth of the fluid. For these sensors, using chemically compatible materials is important to assure proper performance. Sensors are commercially available from 10 mbar to 1000 bar.
407:
sensor. For liquids prone to foaming and applications prone to splashing or turbulence, capacitance level sensors can be designed with splashguards or stilling wells, among other devices.
188:
or greater). With proper selection of vibration frequency and suitable sensitivity adjustments, they can also sense the level of highly fluidized powders and electrostatic materials.
411:
tremendous mechanical tension due to the weight of the bulk powder in the silo and the friction applied to the cable. Such installations will frequently result in a cable breakage.
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909:
A nuclear level gauge or gamma ray gauge measures level by the attenuation of gamma rays passing through a process vessel. The technique is used to regulate the level of molten
633:
544:
For use in open air applications, where the sensor cannot be mounted to the bottom of the tank or pipe thereof, a special version of the hydrostatic pressure level sensor, a
565:
addition, a variable air pressure would affect the measurement result. Typical air pressure fluctuations of about +/- 20 mbar, corresponding to +/- 20 cmWs (water column).
269:
is the installation of temperature or pressure sensors to create a multi-parameter sensor. Magnetic float switches are popular for simplicity, dependability and low cost.
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Nucleonic level sensors are often used in mineral crushing circuits, where an increase in gamma ray detection indicates a void, compared to being filled with ore.
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controls is consistent across large and small field applications. This universal technology is used in applications with wide-ranging liquid quality.
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by time of flight from pulse to return pulse registry. the time of flight corresponds to the distance from the sensor detecting the return pulse.
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due to moisture, temperature, and pressures. Correction factors can be applied to the level measurement to improve the accuracy of measurement.
387:
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Air bubbler systems contain no moving parts, making them suitable for measuring the level of sewage, drainage water, sewage sludge,
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128:, tank or bin size and shape. Also important are the application constraints: price, accuracy, appearance, response rate, ease of
1065:
330:
of multiple sensing rods of different length allows the user to intuitively set up control switches at various water heights.
144:
A variety of sensors are available for point level detection of solids. These include vibrating, rotating paddle, mechanical (
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1316:
Falahati, M. (2018). "Design, modelling and construction of a continuous nuclear gauge for measuring the fluid levels".
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the frequency on each probe is monitored by a microprocessor which can perform multiple water level control functions.
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Depending on the requirements of the site, hydrostatic pressure level probes offer different features:
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process of steelmaking. The water-cooled mold is arranged with a source of radiation, such as
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An RF admittance level sensor uses a rod probe and RF source to measure the change in
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location, these sensors can be used with aqueous, organic, and corrosive liquids.
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Zhukov, Yuriy D.; Zivenko, Oleksii V.; Gudyma, Yevgen A.; Raieva, Anna N. (2019).
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Piezoresistive silicon sensor, ceramic thick-film sensor, ceramic capacitive
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1276:"Correction technique for guided wave radar lpg level measurement sensors"
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1210:"LPG Accounting Specificity During ITS Storage and Transportation"
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Sensors for both point level detection and continuous monitoring
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the respective mounting height with an offset setting.
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in their containers (or other physical boundaries) because of
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Ultrasonic level sensors are also affected by the changing
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reflected back to and detected by the emitting transducer.
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signals that are proportional to the level of the liquid.
234:
magnetostrictive), ultrasonic, radar or optical sensors.
1066:"A Dozen Ways to Measure Fluid Level and How They Work,"
176:
These detect levels of very fine powders (bulk density:
1258:"60GHz FMCW Cloud Level Radar - Staal Instruments B.V."
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Ultrasonic level sensor used in a water treatment plant
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1052:, Electronic Sensors, Inc., retrieved August 8, 2018
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27:Sensor to detect the level of substances that flow
925:, on one side and a sensitive detector such as a
424:and lessen the effects of build-up on the probe.
156:), capacitance, optical, pulsed-ultrasonic and
140:Point and continuous level detection for solids
578:container, but the filling level is decisive.
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72:. Substances that flow become essentially
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1131:"Apparatus for determining liquid levels"
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1283:Shipbuilding & Marine Infrastructure
272:A variation of magnetic sensing is the "
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453:Continuous level measurement of liquids
449:techniques also improving ease of use.
532:are submersible or externally mounted
184:), and granular solids (bulk density:
982:EngineersGarage (18 September 2012).
7:
1352:"Technical data on nucleonic gauges"
1106:Notes on Instrumentation and Control
309:to meet international standards for
844:Size and number of openings / holes
1359:International Atomic Energy Agency
628:{\displaystyle p(h)=\rho gh+p_{0}}
530:Hydrostatic pressure level sensors
257:possible using a float principle.
172:Principle of vibration point probe
120:, acoustical or electrical noise,
25:
1214:Measuring Equipment and Metrology
321:State dependent frequency monitor
229:Point level detection of liquids
56:and fluidized solids, including
852:Stainless steel, titanium, PTFE
180:), fine powders (bulk density:
1338:10.1088/1748-0221/13/02/P02028
808:
802:
597:
591:
116:(specific gravity) of medium,
1:
1103:G. J. Roy (22 October 2013).
499:Magnetoresistive level sensor
238:Magnetic and mechanical float
1361:. July 2005. pp. 34–39
1227:10.23939/istcmtm2019.03.021
757:height of the liquid column
88:(liquid, solid or slurry),
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1318:Journal of Instrumentation
1109:. Elsevier. pp. 23–.
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241:
29:
1208:Zivenko, Oleksiy (2019).
1191:"Capacitive Level Sensor"
1072:retrieved August 29, 2018
1050:Tank Sensors & Probes
1014:"Fly Ash Level Detection"
1295:10.15589/smi2019.2(12).3
1153:. Morgan-Grampian. 1934.
868:Relative or sealed gauge
30:Not to be confused with
988:www.engineersgarage.com
1195:Level Sensor Solutions
815:
781:
749:
727:
711:gravitational constant
703:
681:
655:
629:
500:
390:
352:
173:
68:that exhibit an upper
1084:"Float Level Sensors"
927:scintillation counter
860:PE, FEP, PURE EPR, PA
816:
782:
780:{\displaystyle p_{0}}
750:
728:
704:
682:
680:{\displaystyle \rho }
656:
654:{\displaystyle \rho }
630:
498:
389:
350:
171:
1171:: 2–. January 1927.
1012:Sapcon Instruments.
823:hydrostatic pressure
814:{\displaystyle p(h)}
796:
789:ambient air pressure
764:
739:
717:
693:
671:
645:
585:
519:Hydrostatic pressure
396:dielectric constants
252:Magnetic level gauge
244:Float (liquid level)
40:Level of measurement
1330:2018JInst..13P2028F
865:Measuring principle
687:≈ 1.000 kg/m³]
311:hazardous locations
106:dielectric constant
1068:December 1, 2018,
948:Level (instrument)
915:continuous casting
811:
777:
745:
723:
699:
677:
651:
625:
509:intrinsically safe
501:
391:
353:
307:intrinsically safe
178:0.02–0.2 g/cm
174:
118:agitation (action)
1116:978-1-4831-0491-1
1070:Sensors Magazine,
873:Sensor technology
748:{\displaystyle h}
733:≈ 9,81 m/s²]
726:{\displaystyle g}
702:{\displaystyle g}
504:Magnetoresistance
415:Optical interface
299:hydrochloric acid
182:0.2–0.5 g/cm
18:Level measurement
16:(Redirected from
1394:
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558:gravity pressure
534:pressure sensors
491:Magnetoresistive
463:Magnetostrictive
458:Magnetostrictive
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126:mechanical shock
50:level of liquids
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984:"Level Sensors"
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980:
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971:
953:List of sensors
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217:Admittance-type
198:
196:Rotating paddle
185:
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166:
164:Vibrating point
160:level sensors.
142:
64:materials, and
43:
28:
23:
22:
15:
12:
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5:
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1165:"MotorBoating"
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1064:Henry Hopper,
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1324:(2): P02028.
1323:
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1289:(12): 27–34.
1288:
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1261:www.senz2.com
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1169:Motor Boating
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1038:
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1005:
994:on 2012-09-20
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186:0.5 g/cm
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55:
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46:Level sensors
41:
37:
33:
19:
1363:. Retrieved
1346:
1321:
1317:
1311:
1286:
1282:
1269:
1260:
1252:
1220:(3): 21–27.
1217:
1213:
1203:
1194:
1185:
1168:
1159:
1150:Chemical Age
1149:
1143:
1134:
1125:
1105:
1098:
1087:. Retrieved
1077:
1069:
1017:. Retrieved
1007:
996:. Retrieved
992:the original
987:
977:
932:
908:
899:
892:
886:
884:
836:
833:Design types
827:
822:
788:
756:
667:[for water:
662:
637:
576:
567:
563:
555:
543:
539:
529:
528:
513:
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485:
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368:
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354:
332:
328:
324:
315:
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296:
287:moving parts
283:
271:
267:
263:
259:
255:
248:Float switch
232:
220:
199:
190:
175:
143:
83:
70:free surface
45:
44:
958:Sight glass
923:caesium-137
887:air bubbler
881:Air bubbler
573:Formulation
546:level probe
525:Depth gauge
382:Capacitance
274:Hall effect
134:programming
130:calibration
90:temperature
48:detect the
36:Dumpy level
32:Tilt sensor
1365:9 February
1135:google.com
1089:2009-05-05
1019:2016-09-22
998:2018-09-16
969:References
963:Tide gauge
943:Fuel gauge
895:night soil
523:See also:
356:Ultrasonic
343:Ultrasonic
293:Conductive
242:See also:
223:admittance
158:ultrasonic
74:horizontal
52:and other
1303:213556435
1244:211776025
1236:0368-6418
1197:. elobau.
1177:1531-2623
919:cobalt-60
905:Gamma ray
675:ρ
649:ρ
604:ρ
552:Operation
432:Microwave
285:sensor's
280:Pneumatic
207:Bentonite
150:microwave
146:diaphragm
122:vibration
102:chemistry
1381:Category
1082:Deeter.
937:See also
94:pressure
62:granular
58:slurries
1387:Sensors
1326:Bibcode
664:density
638:where:
211:fly ash
203:Perlite
114:density
78:gravity
66:powders
1301:
1242:
1234:
1175:
1113:
250:, and
110:medium
98:vacuum
54:fluids
1355:(PDF)
1299:S2CID
1279:(PDF)
1240:S2CID
913:in a
911:steel
154:radar
86:phase
38:, or
1367:2023
1232:ISSN
1173:ISSN
1111:ISBN
1334:doi
1291:doi
1222:doi
921:or
885:An
713:[:
209:or
148:),
132:or
108:of
96:or
1383::
1357:.
1332:.
1322:13
1320:.
1297:.
1285:.
1281:.
1238:.
1230:.
1218:80
1216:.
1212:.
1193:.
1167:.
1133:.
1057:^
1028:^
986:.
821:=
787:=
755:=
709:=
661:=
246:,
205:,
124:,
112:,
104:,
100:,
92:,
60:,
34:,
1369:.
1340:.
1336::
1328::
1305:.
1293::
1287:2
1263:.
1246:.
1224::
1179:.
1137:.
1119:.
1092:.
1022:.
1001:.
809:)
806:h
803:(
800:p
773:0
769:p
743:h
721:g
697:g
621:0
617:p
613:+
610:h
607:g
601:=
598:)
595:h
592:(
589:p
152:(
42:.
20:)
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