Detecting liquid levels with conductive Level Rod-Probes The level rod-probes are available in many different versions: • with two to five rods for detection of one to four different levels and • with or without an integrated temperature sensor. A suitable electronic controller applies a low alternating voltage to the probe rods. A current then flows from the electrically conductive tips of the rods and through the conductive liquid to the reference electrode, called the ground rod. The electrical circuit is closed. If the liquid level drops below the tip of a probe rod, the related electrical circuit is opened. The electronic controller detects the two states “current” and “no current”. The ground rod must be at least as long as the longest rod. An additional ground rod must be provided for level rod probes coated with PTFE-Compound, if the distance between the tips of the minimum and maximum rods is more than 1000 mm. Level rod-probes NS with terminal casing LC In metallic, electrically conductive tanks, no ground rod is needed if the ground terminal is connected directly to the tank. In order to prevent the rods from touching each other, PTFE spacers are fitted on probes with rod lengths of 300 mm or more. The level rod-probes are available with the small terminal casing LC (material PP) or LC/L (material PVDF) and the large terminal casing BC (material PP) or BC/L (material PVDF). Level rod-probes with terminal casing BC can be mounted onto the edge of the tank by the supports HB (PP) or HB/L (PVDF) or on a crossbeam by means of the mounting sleeve EM or the holding sleeve HM. Level rod-probes with terminal casing LC are mounted onto the edge of the tank by the supports HL (PP) or HL/L (PVDF), or on crossbeams by means of the holding sleeve ML. You can assure the safe control and monitoring of the liquid level in your tank by using level rod-probes. Since these are purely passive devices, suitable electronic controllers are needed. Level rod-probes operate on the conductive principle, which means that they can be used only in electrically conductive liquids (conductivity >4 μS). Encrustation and contamination in the tank normally have no effect on the function of the probes. The levels of non-conductive or poorly conducting liquids, in which level rod-probes cannot be used, can be controlled and monitored by our float switches. • monitoring of the level in order to prevent possible damage (dry-running, heating without sufficient liquid) to the devices (pumps, heaters) installed in the tanks or to prevent an overflow of the process liquid from the tanks. • control of the level in order to permit automatic execution of process operations (such as dosing of liquids) Possible deposits of encrustation between the tips of the probe can be avoided by ensuring that the difference between the probe-rod lengths is at least 60 mm. Liquid levels in process and storage tanks need to be measured and monitored, since unwanted variations in these levels (due to evaporation or removal of the process liquids) must be corrected. In this respect, there are two different gen

Controlling and monitoring with safety and quality 71,5 In order to ensure optimal chemical and thermal resistance, the level rod-probes are made from a variety of materials. Code letter Specifications of the standard materials Max. liquid temperature Temp. Sensor material (in case of NT) PTFE, pure-white PTFE, pure-white PTFE, pure-white Number of levels to be detected Number of probe rods Level rod-probes type Level rod-probes with integrated Temperature sensor Pt100 Temperature sensor The terminal casing BC made of PP permits the connection of the cable and has the degree of protection IP...