Abstract: A method of measuring the remaining useful life of a filter may comprise flowing a particulate-laden fluid through a filter, measuring values indicative of pressure drop across the filter, and outputting the values to a store. The store may hold a set of values indicative of pressure drop and the percentage of remaining useful life of the filter represented by those values. On receiving a measurement indicative of pressure drop, the store may find the corresponding stored value indicative of pressure drop and output the value indicative of percentage of remaining useful life represented by the stored value.

Abstract: A method of measuring the remaining useful life of a filter may comprise flowing a particulate-laden fluid through a filter and measuring a parameter of the flow during the flowing. From the measurements of the parameter, measurements of the remaining useful life of the filter that vary linearly during the time in which the fluid is flowing through the filter may be produced. The method may include, storing in a store a previously measured correlation between the parameter and the remaining life for a trial filter corresponding to the filter on flowing the particulate-laden fluid therethrough. The store may receive the measurements of the parameter and output measurements of the remaining useful life corresponding to the received measurements of the parameter and derived from the previously measured correlation.