Filtering stage: The Sheaf Filter™ is made of tens of thousand of threads held as a sheaf inside a cylindrical chamber. Several chambers are then assembled inside a larger tank, the number of chambers defining the volume of the filter.
During filtration, the contaminated water enters the lower part of the filter and flows from the bottom to the top of the sheaf. By the force of water and by differential pressure in the vessel, the sheaf is squeezed into the chamber, filling it up in an even and balanced way. The water then flows lengthwise through micron channels created by the spaces between the threads. An important part of the filtration occurs at the first contact of the water with the sheaf, where the pores created among the threads are the first barrier to the dirt. Further filtration occurs as the water flows through the micron channels inside the sheaf by capillary phenomenon. The shape of the threads, their designed surface area, and the time it takes the water to flow through the sheaf; enable the smallest suspended solids to be intercepted and adhere to the threads. The final result is a remarkable and fine filtration.
Backwash stage: The Sheaf Filter™ has a self-rinsing system that is activated either by time intervals or differential pressure. The backwash functions with the addition of air pressure, creating a flow of water in the opposite direction through the chambers and sheafs. The change in flow direction and change in pressure inside the vessel cause the sheafs to move down until they are partly outside the chambers. As such, the bottom filtration area of the sheaf is no longer held tighlty by the chamber and the threads of the sheaf can spread out, guaranteeing an efficient wash to the main area of contamination in the sheaf. The rest of the sheaf gets rinsed inside the chamber by the pressure of the water flow inn opposite direction as well as by alternating cycles of air and water pressure, creating turbulence and movement throughout the threads.
Each pulse of water and air during the backwash sequence has a duration of 3 seconds only.