Abstract: The invention provides a simple, non-invasive means for measuring pressure of fluid in fluid-containing, resilient tubing by measuring the force to mechanically compress the tubing to a predetermined distance. In the apparatus of the invention, first and second opposed members are moved together to a predetermined distance to compress the fluid-containing, resilient tubing therebetween. Measuring means connected to at least one of the members is used to measure the force exerted by the fluid-containing, resilient tubing against the members when the members are at the predetermined distance from one another, wherein the measuring means has been pre-calibrated at the predetermined distance, to correspond to fluid pressure within the fluid-containing, resilient tubing. An important application of the invention is the provision of a convenient, non-intrusive, low-cost device for field measurement of pressure in drip irrigation systems, without installing special fittings or puncturing the tubing.

Abstract: The invention provides a simple, non-invasive means for measuring pressure of fluid in fluid-containing, resilient tubing by measuring the force to mechanically compress the tubing to a predetermined distance. In the apparatus of the invention, first and second opposed members are moved together to a predetermined distance to compress the fluid-containing, resilient tubing therebetween. Measuring means connected to at least one of the members is used to measure the force exerted by the fluid-containing, resilient tubing against the members when the members are at the predetermined distance from one another, wherein the measuring means has been pre-calibrated at the predetermined distance, to correspond to fluid pressure within the fluid-containing, resilient tubing. An important application of the invention is the provision of a convenient, non-intrusive, low-cost device for field measurement of pressure in drip irrigation systems, without installing special fittings or puncturing the tubing.

Abstract: A variable flow sprinkler head having an inlet, an outlet and a nozzle, the nozzle having an orifice therein, the cross sectional area of the orifice being changeable by alternately inserting or removing a needle into the sprinkler head nozzle orifice. The needle diameter is sized to provide a predetermined flow rate reduction when the needle is inserted into the nozzle orifice. When the needle is removed full flow occurs. When the needle is inserted into the center of the nozzle orifice, the cross sectional area is effectively reduced by an amount equal to the cross sectional area of the needle. A linear actuator for the needle is centered above the outlet. The linear actuator may be either an electric solenoid or a hydraulic actuator. Alternatively, the linear actuator may provide a mechanism to allow the sprinkler to be operated between either of two preselected flow rates or in the alternative to be shut off completely.

Abstract: Water pressure in various branches of an irrigation system is controlled by incorporating a butterfly valve in each branch. Each valve is connected to its own piston-cylinder hydraulic assembly. Elongation of the assembly urges the valve toward closure. Shortening of the assembly urges the valve toward opening. A spring operatively associated with the assembly urges the assembly to shorten itself. A tube conveys actuating fluid, i.e., water, into the assembly from the conduit downstream from the valve in opposition to the force of the spring. Whenever the downstream pressure exceeds a predetermined pressure, the actuating fluid overcomes the force of the spring and elongates the assembly thereby moving the valve toward closure. This causes the valve to obstruct the flow of water, thereby returning the downstream pressure to the predetermined magnitude.