BAR SCREENS


Coarse filtration is normally performed by bar screens system, tailor manufactured to withstand required differential heads and normally composed by an heavy rectangular structure made of bars with rectangular section with spaces from 20 to 150mm and appropriate inclination

 

FAI Bar Screens, designed for heavy duty performances, can be removable, fitting guides tracks commonly used for stoplogs, or fixed, strictly connecting the civil work channels by means of anchoring plates previously provided for building into the first phase concrete.
Automatic motorized cleaning systems (fixed or mobile type racking screen) are commonly installed and consists of one or more rakes that sweep the space between the bars, lifting up the solids retained which are discharged at the top into a collecting system (concrete gutter, baskets or belt conveyor).
FAI Racking Screen are of a proven design and operating since 1978 in water intakes located in different countries with the heaviest environment condition.

Automatic and manual operations are always available by combined differential level control, time switch and local push buttons, serial linked or hardwired to FAI PLC control panel or central DCS.
All materials of construction, where not directly indicated by Customer, are carefully selected to guarantee the maximum vital service. Maintenance is never a major requirement.

FIXED AND MOBILE AUTOMATIC RACKING SCREENS

FAI Automatic Racking Screens consist of one rake that covers with alternative movement the surface of the bar grid system, driven by four steel cables connected with two shafts, motor operated. The main shaft is dedicated at the up/down movement while the auxiliary one at the open/close movement.
The teeth of the rake are lowered against the bar during the upward while stay lifted during the downward.
The system is supported by an heavy superstructure with chute, connected to double side guide rails on which the rake can slip and swing. The screen has an automatic cleaning system, consisting of a movable baffle installed at the upper end of the stroke that pushes the solids retained into the discharging concrete gutter where a water flow will provide for the evacuation to the collecting baskets.
Safe operations are guaranteed by overload systems, installed on both shaft, and cable slack switches for the main shaft cables. Furthermore the end strokes of the rake are monitored by limit switches installed in waterproof boxes.
Automatic racking screens are also available with two cables connected with one sole shaft and double side guides with swap for the open/close of the rake.
Fixed racking screens are normally installed in channels having a maximum width of 6 meters. When the intake foresees very large channels or many parallel channels, the cleaning system can be installed on a travelling rake machine running on rails (MTRR – Mobile trash rack rake). The rake can have the same size of the bar grids or in case of channels with different widths, the minimum required.

FAI MTRR can include the following:

  • On board electric power and control system,
  • Single or redounded PLC,
  • Air conditioned closed cabin for operator and control system,
  • Electric or hydraulic motors,
  • On boar trash baskets.

REVOLVING RACKING SCREENS

When the screening system shall be capable to deal with large quantity of jellyfishes or sea grass, the installation of the automatic Revolving Cleaning System is recommended.