Conductive level probe - GALVATEK - #1

Terminal casing LC

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.

The levels of non-conductive or poorly conducting liquids, in which level rod-probes cannot be used, can be controlled and monitored with the aid of our float switches.

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. 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. If the distance between the tips of the minimum and maximum probe rods is more than 1000 mm, an additional ground rod must be provided.

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, a distinction must be made between two general tasks:

• control of the level in order to per­mit automatic execution of process operations (such as dosing of liquids)

• 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.

You can implement safe control and monitoring of the liquid level in tanks with level rod-probes. Since these are purely passive devices, suitable electronic controllers are needed.

Level rod-probes operate on a conduc­tive principle, which means that they can be used only in electrically conduc­tive liquids (conductivity >10 pS). Encrustation and contamination in the tank normally have no effect on the function of the probes.

Ground rod

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 BK (material PP) or BK/L (material PVDF).

Level rod-probes with terminal casing BK can be mounted on the edge of the tank with the support HB or on a crossbeam with the aid of the mounting sleeve EM or the holding sleeve HM.

Level rod-probes with terminal casing LC are mounted on the edge of the tank with the support HL, or on cross­beams with the holding sleeve ML.