Signal device for detecting filter condition

A signal device attachment for a fluid line provided with a filter for passage of pressurized fluid through the filter, said filter being connected to pressurized fluid intake and outlet lines, said signal device comprising

• a. a piston housing and a piston longitudinally movable in the housing, the piston normally being spaced from the inner surfaces of opposite ends of the housing to provide a high pressure and a low pressure chamber, respectively, in the housing, said piston being provided with an annular groove,
• b. a fluid line communicating with the high pressure chamber and having means for connection to the filter intake line, and a fluid line communicating with the low pressure chamber and having means for connection to the filter outlet line, and
• c. signal means activated by fluid pressure in the high pressure chamber when the piston has been moved to the low pressure chamber by unbalanced pressure in the chambers resulting from reduced volume of fluid passing through the filter, and
• d. locking means automatically actuated only by movement of the piston into piston engagement for retaining the piston in signal activating position, said locking means comprising a spring metal plate fastened to the piston housing and a pin extending from the plate through the housing into contact with the groove in the piston preventing movement of the piston while in contact therewith.

A signal device for detecting the condition of a fluid line filter and for automatically giving a signal when the filter needs cleaning or replacement, comprising

• a. a piston housing and a piston longitudinally movable in the housing, the piston normally being spaced from the inner surfaces of opposite ends of the housing,
• b. a fluid line having a filter therein, and pressurized fluid intake and outlet lines communicating with the filter, said pressurized fluid passing through the filter,
• c. a fluid line connecting the pressurized fluid intake line to one end of the piston housing and a fluid line connecting the pressurized fluid outlet line to the opposite end of the piston housing for permitting passage of fluid to opposite ends of the piston housing, and
• d. signal means activated by fluid pressure in the piston housing when the piston has been moved toward one end of the housing by unbalanced pressure in the housing resulting from reduced volume of fluid passing through the filter,
• e. said piston housing having a smaller internal diameter at one end portion and larger internal diameter at the opposite end portion, and the piston has opposite end portions which slidably contact said respective smaller diameter and larger diameter portions of the housing, the space between the smaller diameter end of the piston and the inner surface of the housing end wall providing a high pressure chamber, and the space between the larger diameter end of the piston and the inner surface of the opposite end wall of the housing providing a low pressure chamber when an unbalanced fluid flow into opposite end chambers exists, and
• f. manually adjustable means for varying the pressures required in the opposite end chambers to actuate the piston.

a signal device attachment for a fluid line provided with a filter for passage of pressurized fluid through the filter, said filter being connected to pressurized fluid intake and outlet lines, said signal device comprising

• a. a piston housing and a piston longitudinally movable in the housing, the piston normally being spaced from the inner surfaces of opposite ends of the housing to provide a high pressure and a low pressure chamber, respectively, in the housing,
• b. a fluid line communicating with the high pressure chamber and having means for connection to the filter intake line, and a fluid line communicating with the low pressure chamber and having means for connection to the filter outlet line, and
• c. signal means activated by fluid pressure in the high pressure chamber when the piston has been moved to the low pressure chamber by unbalanced pressure in the chambers resulting from reduced volume of fluid passing through the filter, and
• d. manually adjustable means for varying the pressures required in the opposite end chambers to actuate the piston.