A Streaming Current Meter measures positive and negative ionic / particle charges in water. It is used for coagulant control (chemical dosing) in a variety of applications such as potable (drinking) water, wastewater, and industrial processes (ie. papermaking).
The sensor generates a signal with a reciprocating piston and cylinder which shears counter ions in the sample. Electrodes detect the streaming current signal polarity and magnitude and transmits it to the meter for processing and display purposes.
Streaming Current measures colloidal particle charge and not just specific ionic concentration. Streaming current also indicates the polarity of the charge (positive or negative).
Streaming Current doesn’t measure Zeta Potential directly, but there is typically good correlation with Zeta Potential measurement. While Zeta Potential is calculated from the motion (mobility) of a particle caused by an induced electric field, streaming current is a measure of the electric current from induced particle motion.
The SCM should be installed to sample the treated water just downstream of the coagulant addition. A sample which is well mixed with chemical is preferred. In sludge dewatering applications such as belt presses or centrifuges, the SCM should sample the filtrate or centrate.
The SCM will detect the charge neutralizing effects from alum and ferric based coagulants as well as polyaluminum chloride and other “charge based” polymers.
The SCM probe must be cleaned periodically to maintain sensitivity to process changes. The frequency depends on the application. This cleaning can be performed manually or with an optional automatic self cleaning system.
The probe housing includes a disposable Teflon® sleeve, which may be replaced independently of the electrodes. The upper and lower electrode are also independently replaceable to facilitate easy servicing of the probe.