The arrangement is classed as a type ‘A’, meaning that it is configured for the well to flow from the inside of the filter and the sand to collect therein. 

The principle of sand filtering is well understood, with the size of the separated particles determined by the mesh size in the filter elements. Continuous operation is achieved by switching the flow between the two pots and draining the collected sand from the bottom of the pot that is isolated from the flow. 

The assembly is also equipped with a water flushing system utilising fixed pipework and nozzles, providing the option to purge at lower pressure with water.