APG LPU-2127 Loop-Powered Ultrasonic Sensor
The LPU-2127 is designed for easy set-up. Wiring is fast, and programming is done entirely through the integrated keypad. With CSA hazardous location certification, and a durable housing with high chemical compatibility, this ultrasonic sensor performs well under stress. The LPU-2127 is loop-powered for faster, more efficient wiring, and the easy interface and keypad eliminate the need for a computer. The sensor is virtually maintenance-free!
Ultrasonic 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 reflected back to and detected by the emitting transducer. Ultrasonic level sensors are also affected by the changing speed of sound due to moisture, temperature, and pressures. Correction factors can be applied to the level measurement to improve the accuracy of measurement. 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 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.
Endress & Hauser Time-of-Flight Levelflex FMP51
Levelflex FMP51 for level measurement even under extreme process conditions like high temperature and high pressure in the process industry. FMP51 offers maximum reliability even in case of moved surface and foam or when numerous tank baffles interfere with the measurement. Levelflex FMP51 is used for continuous level measurement of liquids, pastes and slurries but also for interface measurement. The measurement is not affected by changing media, temperature changes, gas blankets or vapors.
Guided-wave radar (GWR) is a contacting level measurement method that uses a probe to guide high-frequency electromagnetic waves from a transmitter to the media being measured. GWR is based on the principle of time-domain reflectometry (TDR). With TDR, a low-energy electromagnetic pulse is guided along a probe. When the pulse reaches the surface of the medium being measured, the pulse energy is reflected up the probe to circuitry that then calculates the fluid level based on the time difference between the pulse being sent and the reflected pulse received. The sensor can output the analyzed level as a continuous measurement reading via an analog output, or it can convert the values into freely positionable switching output signals. Unlike older technologies, GWR offers measurement readings that are independent of the chemical or physical properties of the process media with which it is in contact. Additionally, GWR performs equally well in liquids and solids.
Endress & Hauser Time-of-Flight Micropilot FMR50
Micropilot FMR50 is the best choice in simple reservoir and storage applications as well as in utility processes. The Micropilot FMR50 is used for continuous, non-contact level measurement of liquids, pastes and slurries. The measurement is not affected by changing media, temperature changes, gas blankets or vapors.
In free-air radar measurement, a signal is sent from a non-contacting device and received back at the device. Using either transit time or frequency modulation techniques, the distance from the device to the level is derived, and used to calculate the level of the liquid or solid being measured. Free-air radar works much better than ultrasonic level gauges and is significantly less costly than nuclear level gauges or laser level devices. It's substantially immune to vapor blanket variation in the vessel, to steam, dust and foam in the vessel, and can be easily removed for cleaning and calibration. Free-air radar solves many of the problems of difficult level measurement applications. You're able to mount the device in many existing vessels using an existing connection, which is normally 4 in. to 12 in. Vessel nozzles on many vessels are unused and available.
APG FL Multi-Point Float Switch
The FL multi-level float switch comes made to order. From switch configurations to float types and materials, the FL level switch adjusts to meet your specifications. Unlike suspended float switches that require room to operate, this vertical float switch works along a probe, or stem, for linear level measurement in a tight space. The FL float switch offers up to 7 switch points for increased control and savings. Monitor 7 different levels with a single sensor, and a single mount.
These "multi-station" units offer the most practical way to monitor multiple liquid level points within a single tank. Only a single entry point into the tank is required, and all electrical wiring emanates from a single source. In addition to tracking changing level points of a single liquid within a tank, "multi-station" float level switches are ideal for monitoring liquid interfaces and emulsions in vessels simultaneously containing two or more liquids.
APG KA 1-Level Float Switch
From a stronger cable, to a high chemical compatibility, to durable components, the KA level switch is built to outlast any other. In addition to normally closed, or normally open, the KA single point float switch can be configured with both high and low alarms, as well as dual low or dual high alarms. Unlike some of our competitors, these cable-suspended float switches are mercury and lead-free.
Cable suspended float switches require tanks that are large enough to accommodate the arc of their incline. In conjunction with size, you must also decide whether or not you have the resources required to transport and mount a stem that could measure over 12 ft. in length. Cable suspended floats, can be moved easily while stored in a small box and can simply be “dropped” into the tank with no mounting required. In applications that have tanks with agitators, cable suspended float switches are not a good solution since they would be free to flow with the current of the swirling liquid.
APG RPM Liquid Level Probe
This level probe is built for heavy-duty applications that require ATEX or CSA intrinsic safety, or CSA explosion-proof certifications. It’s large float works well in dirty environments, and has been proven for years in the oil & gas and wastewater industries. Made to OrderProbe length, float type, specific gravity, even outputs can all be customized to your needs. The RPM liquid level probe is meant to work for you.No Fuss OperationThe RPM level float doesn’t struggle with many of the same variables that plague non-contact forms of measurement. With simple linear measurement, there is little that can disrupt the operation or the accuracy of the RPM.
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 signals that are proportional to the level of the liquid. 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, 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.
Kobold NE - Conductive Level Switch
NE series conductive liquid level switches are used to monitor the level of moderately to strongly conductive liquids (>20 uS/cm) only. These conductive liquid level switches work through measurement of the electrical resistance between a sensing electrode and a reference electrode. The simple design incorporates no moving parts and makes these conductive liquid level switches especially suitable for difficult applications, such as monitoring the level of low-density liquids, high viscosity liquids, or liquids containing large quantities of suspended particulates. A complete NE Series level switch system consists of a reference electrode, a sensing (control) electrode and a relay/power supply. Up to six conductive electrodes may be mounted on each NE Series unit, for a total of up to six switch points. A wide range of available materials, including 316-Ti Stainless Steel, Hastelloy® or titanium with optional polyolefin or PTFE coating of electrodes, makes NE conductive liquid level switch ideal for use with corrosive or dirty media.
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, hydrochloric acid, 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. 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 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 “Intrinsically Safe” to meet international standards for hazardous locations. 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. 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.
Kobold NRF - Capacitance Level Transmitter
The NRF Series capacitance level transmitter is designed to measure water-based liquids or oils in metal tanks. The probe measures level by measuring the change in capacitance as level changes in the tank. The transmitter’s microprocessor-based electronics convert this minute capacitance change into a linear, highly accurate 4-20 mA, loop-powered signal. The compact, microprocessor-based design makes installation and set up a simple task. Advanced signal conditioning circuitry greatly minimizes the adverse effects of coating media. The NRF Series capacitance level transmitter is available in rigid and flexible probe versions. An NPT threaded fitting and Tri-Clamp® sanitary fittings are available as standard items. The standard probes for conductive media are PFA-clad to stand up to aggressive media. The KOBOLD NRF Series capacitance level transmitter is truly designed with tough applications in mind. Alternate versions of the NRF Series capacitance level sensor, such as high-sensitivity units for non-conductive fuels and oils, are also available. Consult the NRF product line overview for details on other models.
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 dielectric constants 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 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. 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 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. 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 sensor. For liquids prone to foaming and applications prone to splashing or turbulence, capacitance level sensors can be designed with splash guards or stilling wells, among other devices. 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 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.
APG VBL Vibrating Level Switch
The VBL vibrating level switch works well with solids of many types and for silos and bins or many shapes and sizes.Mounting OptionsBeyond top or side mount, the VBL vibrating level switch features a few options for mounting types, including plug and flange mounts.Sensitivity AdjustmentsThe VBL vibrating level sensor allows you to adjust the sensitivity setting to accurately detect the presence of different types of solids. Settings include low, standard, high, and very high, for solids from sticky to the highly liquidized.
These detect levels of very fine powders (bulk density: 0.02 g/cm3 – 0.2 g/cm3), fine powders (bulk density: 0.2 – 0.5 g/cm3), and granular solids (bulk density: 0.5 g/cm3 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. 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. 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.