Raw water is pumped into the filter through a constant rate of flow valve. This valve maintains a fixed flow rate through the filter despite changes in up stream and down stream pressures. Discharge from the filter goes through CV-4, an air to open, spring to close valve and into the clean storage tank. The level in the clean tank is constantly monitored and the filter will start and stop according to the changes in these levels.

When a terminal pressure of 30PSID is reached, the operator will initiate the clean cycle by pressing a button. The clean cycle automatically evacuates the filter plates of any free water and dries the cake. This part of the clean cycle lasts about 4 minutes. The operator then opens the filter plates with the hand wheel. The filter trays can now be removed and the septum and spent filter cake can now be disposed of into a waste receptacle. New septum is placed onto the trays and the trays placed between the plates. The plates can now be closed.

The operator can now push the start button for the second time, which will start the filter pump and the precoat cycle. CV-2, the precoat supply valve, is opened which results in an increased flow rate. The higher flow rate speeds up the precoat and recirculation cycle as well as flushing the downstream areas of any particulate. Precoat requirements are 0.2 pounds per square foot of filter area. This amount, or more, is always available in the bodyfeed tank after the filter has been cleaned. A valve, CV-5B, near the bottom of the bodyfeed tank is opened and clean water and precoat (DE) are directed through the pump and into the filter. Discharge from the filter is directed through valve CV-5A located near the top of the bodyfeed tank. The DE in the bodyfeed solution is deposited on the septum until 0.2 pounds of DE is formed. The precoat cycle takes about 3 minutes.

After precoat CV-5B is closed and CV-1, the raw water inlet valve, is opened. This directs raw water through the filter and into the bodyfeed tank. The filtered water fills the bodyfeed tank until the high level switch opens CV-5, the recirculation valve, and closes CV-5A and CV-2. The flow rate is now back to its normal setting.

The recirculation cycle directs the filtered water back into the filter pump suction. During this cycle the effluent turbidity is checked to assure a 0.5 NTU quality. The bodyfeed tank fill/recirculation cycle takes about 5 minutes.

After the recirculation cycle is complete, CV-4, the outlet valve, is opened and CV-5 is closed. The filter system is now on-line. The total elapsed time is about 15 minutes.

Bodyfeed from the bodyfeed tank is injected into the filter inlet at a rate that is either manually or automatically set.

In the automatic bodyfeed mode, bodyfeed is injected at a rate that is a function of rate of filter inlet pressure rise (a pressure transducer) and the rate of decline in the bodyfeed tank level (a level transmitter). Our patented "Auto Bodyfeed Rate" software calculates the most efficient bodyfeed based on those two inputs.

If the influent turbidity exceeds a preset value, such as 20 NTU, the filter system will shut down and indicate an alarm. If the effluent turbidity exceeds 0.5 NTU, the filter system will automatically go into the recirculation cycle. The recirculation cycle directs the filter effluent into the filter pump suction and back through the filter. When the effluent turbidity drops below 0.5 NTU, the filter will go on-line. If after several attempts to reduce the effluent fail, the filter will automatically shut down and indicate an alarm.