TM 55-1930-209-14&P-19 Table 3-3. Preventive Maintenance Checks and Services for ROWPU System (Continued) B - Before D - Daily Q -  Quarterly D - During W - Weekly S -  Semiannually A - After M - Monthly A -  Annually INTERVAL ITEM PROCEDURES EQUIPMENT ITEM TO BE CHECK FOR AND HAVE IS NOT READY/ NO. INSPECTED REPAIRED OR ADJUSTED AVAILABLE IF B   D   A   D  W  M   Q   S   A AS NECESSARY 3)  Close valve RO14 on hose connected to small threaded drum bunghole. 4)  Disconnect hose containing valve RO14. 5)  Tip drum from vertical position and remove using drum lifter and bridge crane with 2-ton hoist. NOTE Membrane cleaning agent drum is normally painted black. 6)  Use drum lifter and bridge crane with 2-ton hoist to position drum to stand so large bunghole is on bottom and small bunghole is on top when drum is tipped into place. 7)  Connect hose containing valve RO14 to small threaded drum bunghole. 8)  Connect hose containing valve RO13 to large threaded drum bunghole. 4 * * * * Media Filters a.  Check each media filter unit for damage and leaks.  Check vent valve for proper operation.  Replace vent valve as required.  Unscrew existing air vent on top of media tank and install new vent (P/N 51896-1). * b.  Backwash and flush media filters when Pressure in P1 pressure difference between seawater and P2 exceeds pump discharge pressure gauge P1 and 35 psi. media filter output gauge P2 exceeds 35 psi, when MEDIA FILTER LIGHT OK light goes out, or when water sample taken from cartridge filter assembly drain valve RO8 is dirty. 3-11