Omicron Operation Details

Operation Summary

The water enters the filtration chamber and passes through the fine screen to produce surface mechanical filtration at the filtration degree according to the selected screen rating, from 10 to 2000 microns.

As the collected particles accumulate on the inner surface of the fine mesh, their build-up causes a progressive loss of pressure between the filter inlet and outlet. When the differential pressure reaches 0.3 bar (about 4.5 psi), two analog transducers initiate the backwashing sequence. (Other backwash triggers are available, such as time delay, combined pressure and/or time delay, or continuous backwashing.)

When the DP switch reaches 0.3 bar (4.5 psi), the drainage valve is signaled to open. This generates a pressure differential between outside (atmospheric pressure) and inside the filter (working pressure), which induces a current of fast-flowing water that rushes through the mesh and out through the inner hole of the suction scanner nozzles. At this point a signal is sent to the motor to start operating.

The result of simultaneous (1) spiral movement of the suction scanner inside the filter with (2) suction effect from the nozzles on the accumulated filter cake, enables successful cleaning of the fine screen.

During the 25-second self-cleaning process (or 32 seconds for 10-micron filters), filtered water flows without interruption to the intended application.

Labeled cutaway of an Omicron Filter

Operation Details

The water flows into the filter body and through the stainless steel coarse filter element (Horizontal units only) outside in, keeping large debris from entering the fine screen. Once water flows through the coarse screen, the water enters the stainless steel fine filter element inside out, allowing the dirt to accumulate on the inside surface of the element. A Differential Pressure Switch (DPS) senses the pressure differential across the filter as filter cake builds up on the element. The DPS signals the PLC control panel to initiate the cleaning cycle when PD reaches the 0.3 bar (4.5 psi) threshold, visible on the PD display. During the flushing cycle, there is no interruption of flow. With a clean screen at the maximum flow rate, the filter shall lose less than 1 psi. The filter operation and flushing is controlled and monitored by a touchscreen PLC control panel. The PD set point is user adjustable via the HMI touchscreen. The panel, and its related circuitry, is housed in a NEMA 4X-rated enclosure. A single point power connection controls operation.

The water flows into the filter body and through the stainless steel coarse filter element (Horizontal units only) outside in, keeping large debris from entering the fine screen.  Once water flows through the coarse screen, the water enters the stainless steel fine filter element inside out, allowing the dirt to accumulate on the inside surface of the element.  A Differential Pressure Switch (DPS) senses the pressure differential across the filter as filter cake builds up on the element.  The DPS signals the PLC control panel to initiate the cleaning cycle when PD reaches the 0.3 bar (4.5 psi) threshold, visible on the PD display.  During the flushing cycle, there is no interruption of flow.  With a clean screen at the maximum flow rate, the filter shall lose less than 1 psi.  The filter operation and flushing is controlled and monitored by a touchscreen PLC control panel.  The PD set point is user adjustable via the HMI touchscreen.  The panel, and its related circuitry, is housed in a NEMA 4X-rated enclosure.  A single point power connection controls operation.

Cutaway of Omicron filter showing backwash process

Cleaning Mechanism

The filter cleaning mechanism consists of a spiral-moving suction scanner, constructed of a 316 stainless steel assembly. By opening a 2” flush valve, the scanner creates high efficiency suction force on each of the cleaning nozzles. During that time, the nylon brush nozzles clean the total area of the screen. The nozzle head contacts the screen surface at a constant pressure in order to maximize cleaning efficiency. The flushing flow rate depends on the model; for the largest unit, Omicron 21300, it does not exceed 150 gallons per minute.

Assuring a maximum flush flow rate of 150 gpm regardless of pressure is enabled by a flow control valve in the drain line. For 10 micron screens, the motor driving the suction scanner is factory-set to operate at a slightly reduced speed to ensure successful screen cleaning. Accordingly the cleaning cycle is completed in 32 seconds or less (25 seconds for 25 micron and larger perforation screens), consuming approximately 80 gallons (Model 21300 / 10 micron). The minimum pressure required for flushing is 45 PSI during the flush cycle.

Driving Mechanism

The suction scanner is driven by a 0.5 hp (0.37 kW) electric motor connected to the suction scanner through a threaded shaft that travels inside a threaded bearing. The movement created by the electric motor causes the scanner to move in a spiral motion at a speed of 17 RPM (@208V AC 60 Hz). Other powers, e.g. 460V, are available. The control of the scanner by the electric motor is limited by two normally closed limit switches, and monitored by the control panel.

Closeup of a 10 micron screen

Filtration Element

The filter element is a patented construction comprised of a combination of wedge and weave wire screens, consisting of four layers, fabricated together in order to achieve both greater open area and mechanical strength. The collective screen is made of 316L stainless steel. The screen’s external support is constructed of wedge-wire for mechanical strength. The fine weaved-wire screen is sandwiched (protected) between two 2000-micron weaved-wire additional layers. The total surface area of each screen depends upon the unit size (model # = cm2 screen area). The screen is constructed so as to be able to withstand an internal to external pressure differential of at least 100 PSI without any damage.

Housing Construction

The filter housing is made of 316L stainless steel, or it may be ordered of high-grade S235J coated carbon steel. The filter body has a maximum operating pressure of 145 PSI, or it may be ordered with a higher pressure rating, up to 350 psi. It will have a maximum operating temperature of 120° F (may be ordered with higher temperature capacity). The filter housing shall have the capability to accept filter elements with varying micron degrees, which are totally interchangeable in the same housing.

Note: Replacing a filter element with another of a lower micron perforation in the same housing will reduce the maximum available flow rate the filter can accommodate.

Closeup of a Siemens control panel

Control System

The filter control system consists of a NEMA4 PLC with HMI that controls all aspects of the filter's operation including: Monitoring the DPS and limit switches, and operating the flush valve, electric motor, flush line pump (if included) and by-pass valves. The control panel includes a flush counter to monitor average flush intervals. Control features include dry contact outputs to remotely indicate flush in progress and fault events, and inputs to remotely initiate a start or stop of the filtration system.

The filter conforms to international quality code ISO-14001. It meets or exceeds all current US domestic quality requirements for filtration devices including, but not limited to, NSF, ANSI, AWWA, ASE, and others.

Note: The manufacturer reserves the right to change product specifications without prior notice.