Rev: 09.2017
EBS Pre-Engineered Skid IOM
5
DESCRIPTION OF FILTER OPERATION
Filtering process:
The EBS series HVAC filter system is a sophisticated yet easy-to-operate automatic filter, with a self-cleaning
mechanism driven by an electric motor. The filter system is also equipped with pump, control panel, isolation
valves, and check valve all installed on a skid. The EBS filter system is designed to work with various types of
screens in filtration degrees from 10 to 500 micron (HVAC STD is 50 micron).
The water enters through the pump inlet into the filters coarse screen from outside in, and through the fine
screen from inside out. The "filtration cake" accumulates on the fine screen surface and causes pressure
differential to develop.
The coarse screen is designed to protect the cleaning mechanism from large dirt particles and is not cleaned
automatically. Usually, it does not accumulate large quantities of suspended solids that will inhibit system flow.
Self-cleaning process:
The EBS will start the self-cleaning process when the pressure differential across the screen reaches a pre-set
value or a predetermined lapse of time.
Cleaning of the filter element is carried out by the suction scanner, which rotates in a spiral movement while
removing the filtration cake from the screen and expels it out through the exhaust valve.
The scanner rotation is operated by a 2-way (fwd/rev) drive unit which is attached to the scanner by a threaded
shaft, providing the linear movement.
The exhaust valve is activated for the duration of the cleaning cycle by a 3-way solenoid. During the self-cleaning
process, which takes approximately 35 seconds, filtered water continues to flow out of the filter.
System Operation modes:
The filtration system may be found in one of the following modes:
1.
Filtering mode:
This is the normal operating status. The flush mode is idle and the power light on the
control board is lit.
2.
Self-cleaning mode:
The motor and exhaust valve are activated according to the previously described self-
cleaning process.
3.
Malfunction mode:
If the filter malfunctions, the self-cleaning operation stops and the malfunction light on
the control board is turned on.
The filtration system enters a malfunction mode under any of the following conditions:
1st. A continuous signal from the pressure differential switch longer than the PD fault time-out (default
value=15 minutes) indicates that the filter is unable to clean itself.
2nd. The pump or drive motor Over Load Protector was activated, either manually or due to actual over load.
3rd. Limit Switch malfunction – usually, simultaneous activation of both limit switches.
Initiation of self-cleaning:
The filter initiates the self-cleaning process under any one of the following conditions:
1. Pressure differential (PD) – The Pressure Differential Switch (PDS) closes a free potential contact signal
when the pressure differential across the screen reaches the pre-set value (usually 0.5 bar =7 psi). The
control board registers the signal and activates the self-cleaning cycle.
2. Test - Manually pressing the "TEST" push button on the control board door activates a single self-cleaning
cycle.
3. Timed – The timer in the control panel activates the self-cleaning cycle at time intervals, regardless of the
pressure differential. The timer resets after every cycle. The PD mode is active in this mode as well.
