The Armfield Deep Bed Filter Column is a clear acrylic unit with a flanged end to allow easy access. The medium is supported on a corrosion-resistant gauze mesh below, packed with 1kg of 10mm Ballotini to ensure good wash water distribution. Slotted sampling tubes inserted through the wall penetrate into the media, and are fitted with control valves so that suspension samples can be taken isokinetically. Pressure sensors are mounted on the column 40mm apart, inclined at 60° allowing pressure drop across the column to be recorded.
These sampling and pressure sensor probes are located at 40mm depth intervals, but staggered in position, over 0.8m depth. Consequently, complete profiles of concentration changes in the suspension and of pressure variation can be measured during filter operation. The column can be operated as a pressure filter up to 1 bar. The service system supplied comprises a pump, sump tanks, flow sensors, control valves, sparging device, sampling ports and 21 pressure sensors.