Liquid drainage system with pneumatic sensor

Abstract

In a frost-free water supply system that drains down to avoid freezing, during non-pumping periods, operation of the system is responsive to pressure changes within the system. A pneumatic relay sensitive to changes in one of the fluid pressures operative in the system is located in a portion of the system subject both to water pressure and to the air pressure operating in the system, to provide a pneumatic signal that activates or de-activates one or more system components. One arrangement has a water line discharging into an animal watering bowl within a protected environment. The pneumatic relay is in pressure sensing relation with a localized portion of the water line that remains undrained when the major length of the hose is drained. The pneumatic relay subsequently senses a drop in water pressure, responsive to the re-filling of the bowl. The pneumatic relay is connected to a distant relay, to switch on the pump and recharge the water line, to re-supply the bowl. The relay also may control other system functions, such as reacting to a sharp local rise (or 'bump') in pneumatic pressure that occurs in the system at the moment of closure of a float valve, to actuate a relay operating the water line drain valve, or even to switch off the pump. In another embodiment, a low voltage electric float switch located in a water bowl may be used to actuate a master solenoid, to switch on the water supply. A series of such bowls, each with its own float switch may be used, to achieve individual water supply to each bowl from a common, air-charged, frost-free water supply line. This arrangement generally would have line drain valves, to ensure line drainage and an absence of freze-up potential in the line segments between the bowls.