Abstract: This invention relates to a valve assembly including a hollow body housing a tubular flexible diaphragm therein to provide a passage for fluid flow through the body. The assembly includes means whereby pressures within the diaphragm and in the chamber between the diaphragm and the hollow body are controlled so that, in use with fluid flowing through the diaphragm, it will be caused to automatically and repeatedly contract and expand. This will result in a pulsating flow of fluid through the assembly. Such a valve assembly finds particular application in a swimming pool cleaner operating off the reduced pressure provided by the pump for the conventional pool filtration plant and this invention includes a cleaner of this type including a valve assembly as set forth.

Abstract: A monitoring system comprises a sensor responsive to acceleration in a predetermined plane and an electronic circuit responsive to the sensor for indicating details of the acceleration. The sensor has a float structure immersed in liquid in a casing and mounted for pivotal movement when the sensor is subjected to acceleration in the predetermined plane. The float structure has a pair of spaced floats having centers of bouyancy above and one on each side of an axis of rotation for biassing the float structure to a datum position. Openings are provided in the float structure at different angular positions about the axis of rotation.