Pressure Sand Filter

The Sand Filter is a depth filter that makes use of coarse and fine media mixed together in a fixed proportion. This arrangement produces a filter bed with adequate pore dimensions for retaining both large and small suspended particles.

This filter performs at a substantially higher specific flow rate than conventional filters. Specific flow rates of 15-30m/h have been successfully obtained for treating water containing 50-25ppm suspended solids respectively to produce a filtrate with less than 5ppm.

Features :
• Higher specific velocity.
• Raw water can be used for backwashing the filter.

Advantages :
• Higher specific flow rate than conventional down flow filters thereby saving on Space & cost.
• Very little maintenance required.
• Lower backwash water requirement.
• In most cases, raw water can be used for backwash.

Applications :
• The sand filters filter is an ideal choice for all applications where a conventional sand filter is used.
• It is extensively used in side stream filtration of cooling water & in potable water treatment.
• It is ideal for filtration of clarified water.
• In addition it finds application in sea water filtration & in filtration of chemical solutions.
• For these types of filtrations rubber lined or epoxy painted filters can be offered.

Specifications :
• One vertical cylindrical Mild steel/FRP pressure vessels with dished ends. Mild Steel pressure vessel are painted internally with anticorrosive bitumastic paint and externally with a protective coat of red oxide primer.
• One set of internal water distribution & collection system.
• One initial charge of filter sand & underbed material
• One set of frontal pipe work & valves.
• Two pressure gauges to monitor head loss across the filter.
• One orifice board (optional) for indicating wash water flow to be fitted in drain sump. Maximum / minimum operating pressure will be 3.5kg/cm2g & 2.0 kg/cm2g respectively.
• Multigrade sand filters are available from 600 to 3000mn diameters.

How the Sand / Media filters work:
Water enters through the filter inlet and percolates through the filter bed. When suspended matter comes in contact with media particles, it absorbs it. Clean water Then goes via the filtration nozzles through the filter outlet. Cleaning is done by backwashing. Water is inserted in reverse direction - from the nozzles upwards, causing suspension of the filter bed, thus releasing the suspended matter from the bedding and it is flushed out through a backwash valve. Backwashing may be done automatically according To pressure differential and/or according To time.

1. Water inlet 2. Water 3. Sand bed 4. Water outlet 5. Filtration 6. Service port 7. Media filling