| 摘要 |
A method and a filter unit for cleaning a liquid which circulates in a closed circuit, such as a central heating circuit, from particulate contaminant material, such as magnetite particles, comprises introducing into the circuit liquid soluble chemicals which are active in suspending and agglomerating the contaminant particles, and filtering the circuit liquid with the aid of a filter cartridge whose smallest filter medium openings are larger than a substantial proportion of the contaminant particles. By limiting the flow rate of the liquid through the filter cartridge to a given maximum filter surface load, corresponding to a value at which at least a 70 % reduction of a standard contaminant consisting of kaolin clay Grade C, EEC International, is obtained across the filter, the filter capacity is utilized to a very high degree and favourable separation or extraction of the contaminants is achieved. The filter unit may include a rate of flow limiting means which functions to set the throughflow to a value which will provide the maximum filter surface load in question essentially independently of the pressure drop across the filter. |
