A Streaming Current Monitor (also called a Streaming Current Meter or Streaming Current Detector) is an instrument to measure the surface charge on particles in a liquid This measurement most commonly used in controlling. The dosage of coagulant before the settling process in water treatment. The exact level of streaming current for optimal settling will depend on the plant. Once this has been determined, by knowledge, experimentation or jar tests, a Streaming Current Monitor can be used to automate the process of coagulant dosing to maintain optimal coagulant dosage levels, even in the presence of raw water changes. Streaming Current is directly related to Zeta Potential, but is not the same measurement.
Principle Of Operation
Extremely small particulates suspended in a solution will often have a surface charge. This means that even after a long time in a settling tank the particles will not coagulate and settle out of suspension. To neutralise this charge a material called a flocculent, containing particles with the opposite charge, can be added. When the overall surface charge is balanced the suspended particles will then bind with the flocculent and settle out.
A measurement of the charge on particles in solution can be made by measuring the current produced when the particles are rapidly moved.
The Accufloc uses a piston reciprocating in a closed chamber to create a high rate of flow along the chamber wall. This moving charge is a current (called the Streaming Current) and can be measured between two electrodes at opposite ends of the chamber.
This signal is amplified and processed to give a reading that is a direct indication of the dosage required to exactly neutralise the surface charge on particles in the solution.
- Advanced digital signal processing. The microprocessor runs an algorithm custom designed for the streaming current signal. This algorithm takes into account the shape of the small current signal generated by the sensor, rather than simply rectifying filtering and in the traditional way. This allows a much quicker response
- Excellent immunity to electrica l noise both because o f the shielding characteristics of the metal construction and the advanced signal processing. Other makes of SCMs are well known for vulnerability to interference.
- Optional ushing mechanism. Automatically timed and controlled cleaning of the inside of the sensor chamber.
- Industrial sized motor, all metal enclosure and mechanical parts. All the other SCMs on the market are mostly – if not entirely – constructed with plastic parts.
- Dual display. The only SCM with two displays, one for the un-adjusted streaming current value and one for the distance of this value from the set-point. This way you can tweak the set-point up and back in an absolutely repeatable manner. If the SCM zero ofset needs to be adjusted regularly this dual display makes it easier for the operator once they get used to it.
- Optional built-in controller. This avoids the needs for a separate PID controller in small plants.
- Lower cost. Manufactured with new-millennium technology, allowing us to keep our costs down.