Abstract: An apparatus for dosing a fluid flow system with treatment fluid/chemicals is described. The apparatus includes a vessel; an inlet pipe or hose and an outlet pipe for coupling to the system so that fluid from the system may flow into the vessel and return into the system to flush chemicals from within the vessel and into the system. The vessel has a piston within it and the vessel wall defines a cylinder in which the piston moves under pressure of incoming fluid from a first position at which the vessel contains fluid to be dispensed into the system to a second position corresponding to substantially complete emptying of the vessel. The piston has a bypass passage through or around it that opens when the piston substantially reaches the second position so that fluid from the system may flow passed the piston when the piston is at the second position.

Abstract: Apparatus for dispensing a dose of fluid, the apparatus comprising a dispensing vessel with a dispensing outlet, the vessel having a piston and a vessel wall defining a cylinder in which the piston may move under pressure from a first position to a second position, wherein the apparatus has a bypass passage that extends through the first piston and has a valve member that is opened by a valve actuating plunger in the piston that moves within the piston to push the valve open when the valve actuating plunger abuts a shoulder at or near the second position in the vessel; wherein the shoulder at the second position is an annular shoulder and the apparatus is adapted to dispense fluid in a sequence of stages comprising a mixing stage and a dispensing stage.

Abstract: An apparatus for dosing a fluid flow system with treatment fluid/chemicals is described. The apparatus includes a vessel; an inlet pipe or hose and an outlet pipe for coupling to the system so that fluid from the system may flow into the vessel and return into the system to flush chemicals from within the vessel and into the system. The vessel has a piston within it and the vessel wall defines a cylinder in which the piston moves under pressure of incoming fluid from a first position at which the vessel contains fluid to be dispensed into the system to a second position corresponding to substantially complete emptying of the vessel. The piston has a bypass passage through or around it that opens when the piston substantially reaches the second position so that fluid from the system may flow passed the piston when the piston is at the second position.

Abstract: An apparatus for dosing a fluid flow system with a treatment fluid/chemicals is described. The apparatus includes: a vessel; an inlet pipe and an outlet pipe for coupling to the system so that fluid from the system may flow into the vessel and return into the system to flush chemicals from within the vessel into the system. The vessel has a piston within it and the vessel wall defines a cylinder in which the piston moves under pressure of incoming fluid from a first position at which the vessel contains fluid to be dispensed into the system to a second position corresponding to substantially complete emptying of the vessel. The piston has a bypass passage through or around it that opens when the piston substantially reaches the second position so that fluid from the system may flow passed the piston when the piston is at the second position.