Duplex strainer or twin basket strainer is a kind of of filter constructed into a piping system of gas, oil or water and used to remove big particles of dirt and debris. Usually, the duplex strainer system comprises of two distinct housings for strainer baskets.
The system also includes a valve handle between the two boxes to divert liquid flow to one strainer while cleaning the other. The valve will work automatically on some strainers and a self-cleaning procedure will be performed by the strainer.
fuel oil system uses duplex filters. Only one filter is used at a time, while the other is kept clean.
Cleaning of duplex filter
Filters are cleaned at regular intervals, or when there is a drop in pressure. To clean the filter change over the filter to the other side, which is clean. open the purge cock of the filter in use and ensure that oil flow through the filter. open the purge cock of the filter which is not in use. Open the cover,after the oil stops flowing and take out the filter element.
Be careful when heavy fuel oil is used as it will be very hot. The filter element is made of wire gas. The size of the wire gas depends on the rate of filtration in micron. It is between five microns to 35 microns. clean the filter element with kerosine and compressed air. Put the filter element back with the cover, change over slowly and purge the air from the filter housing.