Napier-Reid’s pressure filtration systems are designed to carry out filtration in a closed vessel under pressurized condition with high filtration rate and ability to operate at higher pressure drop compared to gravity filters and a smaller footprint compared to conventional gravity filters. They are designed for turbidity, iron, manganese, sulfide, and arsenic removal.



  • High filtration rate up to 10 gpm/ft2 (24 m/hr).
  • High solids holding capacity, and ability to operate at high pressure loss, resulting in longer filter runs and reduced backwash water requirement as little as 2% of plant flow.
  • High flexibility in mode of operation.
  • Degree of automation can be provided as per client’s requirement, from completely manual to fully automatic complete with automatic control valves, PLC / SCADA control package, and control panel.
  • Available in vertical and horizontal configuration.
  • Supplied with suitable media: dual bed, multi media bed, GAC, or MD-80 catalytic media for iron, manganese, arsenic, and H2S removal.
  • Well designed feed water distribution system.
  • Efficient under-drain collection / backwash distribution system for minimal pressure drop and proper backwashing.
  • Efficient backwash and air scour system.
  • Package design and multi-tank configuration available. System can be supplied skid mounted, completely assembled, or loose for field assembly on concrete pads.
  • Material of construction – Carbon steel, stainless steel or fiberglass reinforced polyester (FRP), designed for 150 psig pressure.
  • All CS vessels are designed and fabricated in accordance with ASME code. The vessel can be ASME “U” stamped if required.
  • Carbon steel pressure vessel provided with lifting lugs and appropriate sized man ways. Interior lined with NSF approved epoxy suitable for potable water service.
  • Smaller footprint compared to other systems.
  • High degree of automation leads to reduced operator attention and lower O&M cost.


Process Description

In NR–Pressure Filters, the incoming raw water is distributed over the filtration area of the filter through our unique well designed flow distribution system. The water filters down through the different layers of the filter bed. The filtration media mechanically strains out dirt, suspended solids, sediment, algae, bacteria, microscopic worms, cryptosporidium and asbestos, colour, odour, precipitates of iron, manganese, and other impurities.

The filter bed is designed to capture and hold the suspended solids and impurities throughout the depth of the filter bed (and not just at the surface layer), hence increasing the solids holding capacity. The filter bed and internals are also designed to prevent channeling and media upset. The capability of NR pressure filters to operate at higher terminal headlosses and higher solids holding capacity results in longer filter runs and a reduced backwash water requirement.

The filtered water is evenly collected over the filtration area by our unique water collection system that prevents channeling and short circuiting.

When the differential pressure across the filter increases beyond a preset value, the filter bed is backwashed to remove the entrapped impurities in the filter media bed and return the filter to its original filtration capacity. NR filters are equipped with air scouring system and efficient backwash water distribution system for effective backwash.