Control system for a vacuum filter

Claim 2

In combination with a vacuum filter having a liquid-receiving tank, a filter medium underlying the tank, a vacuum chamber receiving liquid from the filter medium, and a vacuum pump in communication with the vacuum chamber for withdrawing filtered liquid from the vacuum chamber, a control chamber adjacent the tank, a conduit between the tank and the control chamber, whereby a level of liquid is maintained in the control chamber substantially equal to the level of liquid in the tank, a control ejector receiving a portion of the filtered liquid from the vacuum pump, a dip tube connected to the control ejector and having an open end in the control chamber at a selected liquid level, a line receiving another portion of the filtered liquid from the pump, the ejector subjecting the dip tube to a reduced pressure when the open end is covered with liquid in the control chamber, valve means in the line for controlling the flow of the other filtered liquid in the line, and pressure-operated means connected to the dip tube and to the valve means for actuating the valve means when the open end of the dip tube is covered by liquid in the control chamber.

Claim 3

A combination as in claim 1 wherein the control ejector discharges into the control chamber, whereby filtered liquid flows through the conduit from the control chamber into the tank and the liquid in the control chamber is filtered liquid.

Claim 4

A combination as in claim 1 wherein the open end of the dip tube is at a selected minimum level of liquid in the tank, the line includes a first branch arranged to return liquid to the tank and a second branch arranged to discharge liquid and the valve means shuts off flow of liquid along the second branch when the open end of the dip tube is uncovered.

Claim 5

A combination as in claim 3 wherein a pump ejector is mounted in said first branch and a side arm is connected to the pump ejector, there being an open end of the side arm for receiving liquid to be drawn through the pump ejector and discharged into the tank.

Claim 6

A combination as in claim 1 wherein the open end of the dip tube is at a selected maximum level of liquid in the tank, the line includes a first branch arranged to return liquid to the tank, a second branch arranged to discharge liquid and a third branch, there is a storage tank arranged to receive liquid from the third branch, and the valve means is arranged to permit flow of liquid along the third branch to the storage tank when the open end of the dip tube is covered.

Claim 7

A combination as in claim 1 which includes a second control ejector receiving filtered liquid from the pump, a second dip tube connected to the second ejector and having an open end terminating in the control chamber at a selected maximum level, the dip tube of the first-mentioned control ejector having an open eNd terminating at a selected minimum level, the second control ejector subjecting the second dip tube to a reduced pressure when the open end of the second dip tube is covered by liquid, the line having a first branch arranged to return liquid to the tank and a second branch arranged to discharge liquid, and a third branch, a storage tank arranged to receive liquid from the third branch, a second valve means in the third branch, the first-mentioned valve means being in the second branch, and second pressure-operated means connected to the second dip tube and to the second valve means and arranged to permit liquid flow through the third branch when the level of liquid in the tank is above the maximum level, the first-mentioned pressure-operated means being arranged to actuate the first-mentioned valve means to shut off flow through the second branch when the level of liquid in the tank is below the minimum level.

Claim 8

A combination as in claim 6 which includes a third control ejector receiving filtered liquid from the pump, a third dip tube connected to the third control ejector and having an open end in the storage container at a selected maximum level for liquid in the storage container, third valve means in the first branch, a pump ejector mounted in the first branch, a side arm connected to the pump ejector, there being an open end of the side arm for receiving liquid to be drawn through the pump ejector to be discharged into the tank, and third pressure-operated means connected to the third dip tube and to the third valve means and arranged to arrest flow of liquid through the third branch when the third dip tube is covered by liquid in the storage container.

Claim 9

A combination as in claim 7 wherein the control ejectors discharge into the control chamber and there is a flow of liquid through the conduit from the control chamber to the tank and the liquid in the control chamber is filtered liquid.