Internormen Filters Private Ltd. Manufactures Pressure Change Over Filter with Vertical Connecting Line. Internormen Filters Private Ltd. Is an ISO 9001: 2000 certified company offering a wide range of filters for hydraulic and lubricating fluids and contamination monitoring system. The Pressure Change Over Filter with Vertical Connecting Line of model number DUV 635 is suitable for operating pressure up to 32 bar and comes with Change-over ball valve between the two filter housings to switch from the dirty filter-side to the clean filter-side without interrupting operation. The Pressure Change Over Filter with Vertical Connecting Line is used for all petroleum based fluids, HW-emulsions, most synthetic hydraulic fluids and lubrication oils.