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� copy <br /> lNc(_osvpc 3 <br /> S . W. P . C . <br /> DE-SLUDGING OPERATION OF THE <br /> ZINC PHOSPHATE BATH <br /> The De-Sludging operation of the Zinc Phosphate Bath is to <br /> remove the excess build-up of settled sludge in the bottom of the <br /> bath and to remove the hardened scale that collects on the plate <br /> heat exchangers . This De-Sludging Operation is very similar to <br /> the De-Sludging operation of the Clarifier, however, the return <br /> valves directs the liquid, back to the HOT WATER TANK, rather <br /> than back to the P-6 Pit . <br /> 1 . Starting with a full tank of Zinc Phosphate Bath, one must <br /> remove the Sludge and Scale in the following manner. <br /> 2 . Drain the Hot Water Bath into P-6 Pit outside and close the <br /> Drain Valve . <br /> 3 . Pump Down the liquid level in the Zinc Phosphate Bath to the <br /> top of the sludge level . <br /> 4 . The liquid pumped out of the Zinc Phosphate Bath is now in <br /> the Hot Water Tank . <br /> 5 . Check the Filter Press Valve Handle positions, making sure <br /> that they are opened correctly. <br /> 6 . Check the Filter Press Console to verify the control <br /> switches are correct : "AIR ON" , "PRESS CLOSED" , "HYDRAULICS ON" . <br /> 7 . Verify the press is closed and all filter plates are <br /> straight . <br /> 8 . The Sludge Pump behind the Zinc Phosphate Bath is normally <br /> off and the valves in the closed position. <br /> 9 . Open the valve at the bottom of the Zinc Phosphate Bath. <br /> Open the ball valve on top of the sludge pump . Open the air <br /> valve entering the sludge pump, making sure the pressure does not <br /> exceed 40 Psi . It is best to start with low air pressure , and <br /> gradually increase the pressure until the pump "stalls out" at 40 <br /> Psi . This should mean that the Filter Press is full . Turn off <br /> air supply and close the valves as in step 8 above . <br /> 10 . Close all valves at the Filter Press except the valve which <br /> is marked "OPEN DURING BLOW DOWN" . This open valve allows the <br /> water in the filter press to return to the Hot Water Tank during <br /> the "BLOW DOWN" cycle, which you are now starting . Open the air <br /> supply valve to "BLOW DOWN" the Filter Press . The maximum air <br /> pressure should be no greater than 30 Psi . You must wait until <br /> the air pressure reaches "ZERO" on the pressure gauge before <br /> 7 <br />