What is  a Hydrastep and what are the for ?

Over the years, numerous companies have entered the drum level market and produced EDLI's. These include Clark Reliance, Fossil Power Systems, Yarway, Narvik, Levelstate Systems, Questtec Solutions, Igema, Penberthy, Tyco, as well as the original company that has been sold and resold numerous times (Solartron, Mobrey, Delta Mobrey (Hydrastep), Delta Mobrey etc.) Many of the systems are very similar and technology has been copied from company to company. There are numerous probes that are interchangeable between different OEM systems. There is nothing special or different about the technology used in the construction of electrodes or conductivity probes, but some manufacturers charge huge prices for spare parts, in some cases over 5 times the price of a Drumline quality direct replacement.

EDLI's work on the principle of resistance, specifically the difference in resistance between steam and water. Because steam has a very big resistance and water has a very small resistance, it is possible to use electronics to turn that resistance into a level indicator. Conductivity probes have a metal stud and tip that are completely isolated from the metal body but a brazed insulator. The probe is inserted into the water column and its body forms part of the earthing (grounding) system of the electronic unit. An alternating electrical current is applied to the probe stud and tip from the electronic unit. When water bridges the gap between the tip and the body, the electrical circuit is complete and the electronic indicates this as a water state. If the water does not bridge the gap, it is indicated as a steam state. Each probe in the system has its own circuit and LED indicator channel.