TM 55-1930-209-14&P-19 Table 4-2.  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 1)  Remove tank lid and fill with 25 gal of drinking water from fill hose attached to bib in void 2 port above holding tank. 2) Add two cans (14 lbs) of sulphuric acid to water in tank for acid flush. 3) Turn valve CU3 to position A, ACID. Turn valve CU5 to position B, ACID. Open valve CU 17.  Make sure valve CU 16 is open. 4) Turn function switch on control cabi- net to FLUSH. 5) Descale until all visible signs of scale are gone from anodes (cells), approxi- mately 5 minutes, then turn function switch to OFF/RESET. NOTE Sump tank pump automatically empties sump tank.  Level switch in sump tank starts and stops sump pump. 6) Turn valve CU5 to position A, DRAIN, to allow solution to drain to sump tank. 7) Remove acid tank lid to observe level of solution in tank. 8) Turn function switch on control cabi- net to FLUSH.  Acid tank should be emptied by circulating pump. 9) When acid tank is empty, turn func- tion switch to OFF/RESET. 10) Close valve CU17 and CU3 to B. 11) Replace lid on acid tank. 4-10