BigPatents India

An oil filtration unit for a tap selector switch comprises a pressure vessel (1), which is connectible into a switch oil circuit of the tap selector switch and which comprises a cylinder (2) with a base and with a removable lid (3) sealingly mounted on an encircling flange (4) at the upper end of the cylinder (2). A removable oil filter insert (18) is arranged in the vessel (1) to filter oil in the oil circuit. For mounting the insert (18), the cylinder flange (4) has a radially inwardly projecting flange portion (17) and the insert (18) has a collar (14) seated on the flange portion so as to suspend the insert (18) in the cylinder (1). The collar (24) can be resilient so as to slightly deform when the lid (3) is fitted. The lid (3) and the filter insert (18) can thus be fitted to and removed from the cylinder (2) of the pressure vessel (1) separately from each other.