Level measurement and control

The LED Tank Display EA01 is developed especially to fit into heavy duty applications in fire engines. It serves as an exact level teleindicator of water and foam tanks. Filling level is indicated by a tricoloured scale of 10 extremely bright LEDs (red/yellow/green). Intermediate steps are indicated by changements of the resp. highest LED’s brightness. For observers it looks like a nearly continuously lit lightbar. The LEDs’ brightness is controlled by a photo sensor. It is readable well in bright sunshine and darkness. This indicator in rugged design is constructed very compact, water- and dustproof and resistant to vibration. It fits into indicator panels. The EA01 is designed for operating voltages 12 V to 24 V DC. It is adjusted ex factory as a unitized measuring signal of 0-5 V, 0-10 V or 4-20 mA. The instrument is protected against voltage reversal and overvoltage. Controlling of tanks at various places is done easily by connecting the desired amount of EA01 in parallel (only for voltage input).

The EA14F is an intelligent multifunction level instrument that measures and displays level when connected to an NC54 or NC56 Capacitive Level Transmitter. The measured value can (optionally) be transmitted to the EA14F as a standardised 2-wire or 3-wire electrical signal. Its programmable limit detection functions enables it also to act as an accurate and versatile level switch. The electronic module converts the analogue signal from the level transmitter and then digitally processes these values. The microcontroller based EA14F has a high degree of user programmability, making it a truly versatile device. The electronic module computes the level, controls the local digital display and (optionally) produces a new analogue signal output. The measurements can be filtered, scaled, inverted or linearised through a user-defined look-up table. The EA14F can be programmed to display the value of either input or converted output signal. The input signal can be converted using its freely-programmable look-up table function for linearisation or conversion to derived units of measurement, e.g., %, m³, Kg, etc. The external level transmitter is connected to and energized by the electronic module through a flexible signal cable terminated by a plug-in connector.

ER76 is controlled by the medium using a type NK06 probe. Input sensitivity is factory-adjusted to 70 kΩ. In order for the relay to switch properly, the mediumconductivity must not fall below a value of 14 μS / cm. When contact is made, an alternating voltage without a direct voltage component flows through the medium, preventing galvanic erosion of the probe material. Depending on the application, location or national regulations, the control electrodes reference potential can be represented by a common electrode as well as by the container itself. After the level probe has been installed and the control relay has been electrically connected, the contact switches to the working position. LED is on. If the maximum level is reached, the output relay switches to the rest position. LED is off. This state remains until the level falls below the minimum level and the contact switches to the working position again. If the supply voltage fails, there is a defect in the control circuit or an interruption in the measuring line, the system goes into the safe state (normally closed contact) and thus prevents the container from being overfilled.

Measuring probes NB10 for hydrostatic measurement of fluid fill-levels. Some examples of typical applications are water or fluid fill-level measurements in wells, drill holes, wastewater systems and containers. This measuring probe is designed around a highly sensitive pressure sensor with a silicon membrane-measuring element. A DMS resistance bridge is attached to the rear of this membrane using a thin-film method. The well probe is equipped with an indirect hydraulic pres-sure sensor in order to guarantee the system-inherent dead space latitude. The pressure sensor is isolated by an elastic membrane from the medium to be measured. The volume between the membrane and the pressure sensor is filled com-pletely with a transfer fluid. When pressure is ap-plied this silicon membrane deforms in the elastic region, altering the resistance of the resistance bridge in a response linear to the measuring pres-sure. These changes in resistance are converted by electronics built into the device into standardized electrical signals.

The capacitive filling level probe NC56 serves to measure tank filling levels in tanks containing fresh water, waste water, faeces, diesel fuel, chemicals and extinguishing foam. Filling level heights of between 400 and 2000 mm can be measured. The probe can be used regardless of the tank material (metal, plastic or concrete). Typical applications is a measurement of tank filling levels for fresh water, waste waster, faeces, diesel fuel, extinguishing foam.

The capacitive filling level probe NC57 serves to measure tank filling levels in tanks containing fresh water, waste water or faeces. Filling level heights of between 400 and 2000 mm can be measured. The probe can be used for tanks made of metal. The tank wall and special rod form the electrodes of the measuring equipment. A condition for the flawless function of the probe is a special probe mounted in parallel to the tank wall. In the case of installation lengths > 700 mm, the rod must be supported by insulated circlips at intervals of 700 mm respectively. The housing is connected to the signal earth, and an AC voltage signal is applied to the special rod. If dipped into a fluid, this arrangement becomes a capacitor and the fluid acts as a dielectric. The capacity values of this capacitor are proportional to the filling height of the tank. Electronics integrated into the device convert these capacity changes into an analogue output signal (current or voltage).

Level probes of type series NK06 are used in connection with transistor control relays ER76 for the automatic control of conductive Liquids and liquid level control. So e.g: monitoring minimum or maximum filling levels in vessels, protection of pumps against dry running, differentiating oil and water levels within enclosed oil/water separators. Once the liquid wets the electrodes, make a conductive connection to the ground electrode or the vessel itself if this is used as ground. The conductivity of the liquid must be at least 5 μS/cm. Contact with the conductive liquid sets the interval relay and the output relay switches. If the liquid level drops below the longest functional electrode, the interval relay is switched off and the output relay drops out.

Уровнемеры серии NK08 используются в сочетании с транзисторными реле управления ER76 для автоматического контроля токопроводящих жидкостей и регулирования уровня жидкости, в качестве защиты насосов от сухого хода, контроля уровня конденсата. Как только жидкость смачивает электрод, создается проводящее соединение с заземляющим электродом, в зависимости от метода работы. Проводимость жидкости должна составлять не менее 5 мкСм/см. Контакт с проводящей жидкостью приводит в действие и переключает выходное реле.

The Fill Level Limiter NK10 can be used in safety-related systems. For use in safety-related systems according to 'Functional Safety' (SIL), the correct function of the safety function must be proven. The swim system of the fill level limiter is contained in the fluid-filled reservoir (expansion tank). The swimming motions generated by changes in the fill level are transmitted directly to the micro-switch S1 by a swimmer rod sealed in a stainless-steel bellows. The fulcrum of the swimmer rod is located outside of the pressure chamber. There is also a test button outside the pressure chamber with which a function check as per DIN 4754-3 can be run without lowering the fill level. When pressed, the body of the swimmer is moved against its buoyancy. The factory default switching point of micro-switch S1 is set so that it switches when the swimmer rod is horizontal. The optional warning switch S2 switches approx. 2.5 mm before S1. The fill level height at which switching is triggered depends on the density of the heat carrier. The lowest density at which a secure function is guaranteed is 0.6 kg/dm³. When the medium has a density of 1.0 kg/dm³, the switching level is approx. 60mm below the middle of the flange or socket.

The level control switch NK21 is suited for the level detection in containers with electrically conductive media. It operates according to the principle of conductive measuring and is suited for numerous measurement tasks. The device has three measuring probes (electrodes) and a common probe (com) that can also be connected to the container if required. The probe lengths can be optionally shortened and therefore adapted to the process. At the electrodes there is a low AC voltage. If these are moistened by the conductive medium, a current starts to flow that is analyzed by the integrated electronics. The threshold limit (resistance range of the medium) can be adjusted in 10 steps by the user. Three PhotoMOS contacts are available as output signal the switching function of which (see wiring diagram) can be set at the plant. The contacts are electrically isolated from the measuring circuit. The switching status is indicated by light emitting diodes. Another light emitting diode indicates the operating status of the device.

The NR56 is a tank level encoder that indicates reliably the level of fuel, water and foam in the tank. Thanks to its sturdy design, it is ideally suited for use in rough environments. It is suitable for various measuring tasks in the following areas: procedural engineering, process technology, environmental technology, automotive engineering, ship technology. The tank level encoder NR56 comprises a probe head with a probe rod with a length between 250 and 1400 mm on which a float magnet can move freely up and down. The probe head is equipped with a screw-in thread for assembly and an M12 connector for the electrical connection. The filling height-proportional signal of the reed chain is sent to the integrated measurement amplifier where it is converted into an electrical uniform signal. The output signal can be sent directly to a display of the type EA01, EA14F or to another analysis system.

The NS01 is a microprocessor controlled level switch for liquid or paste-like and adhesive media. The NS01 is a microprocessor device with integrated interface. In addition to its integrated change-over function it suits sensitivity of the device to dielectric quality of the media. Formation of crusts and drainage behaviour can be visualized and controlled by using the software process diagram. Key features are switching points and - especially - therefore separated setting of hysteresis to suit process. The adjusted value is reproducible by additional actions like dynamic compensation of temperature. To optimize active processes take advantage of the ability of documentation and process monitoring over a larger period. When the NS01 comes in contact with the medium level measurement is done by a high frequency alternating field. It is brought to process through an on media side isolated PEEK-socket. The device is integrated into process through socket welding or modular adaption. The alternating field launched into process is changed by dielectric qualities of the medium (dielectric constant / εr).