Temperature responsive pressure diaphragm valve ensuring delivery of boiling (or near) temperature fluid (water) for use in hand held apparatus for erradication of weeds.

摘要

A portable heating hand tool capable of heating a flow of water to a temperature suitable for killing vegetation. Water flows through an electrical heater within the hand tool, then to a thermally controlled pressure regulating valve (80) and then to an outlet nozzle. The outlet nozzle being separate from the water heating means. The thermally controlled pressure regulating valve has a moveable member such as a diaphragm (83) sealing off a pressure chamber (88). Movement of the diaphragm causes a valve (85) to open or at least partly close. When closed the valve impedes, or restricts the flow of water from an inlet (86) to an outlet (87) through the valve. On the other side of the diaphragm a small quantity of water is trapped within the pressure chamber so that as the valve heats up, pressure with in the pressure chamber rises as the water turns to water vapour and the air within the chamber also expands. This increase in pressure within the pressure chamber causes the diaphragm to move slightly outwardly causing a pintle (84) to allow the ball valve (85) to open and allow maximum flow of the heated water through the valve to the nozzle of the tool.