Abstract: A pool monitoring system includes a hydrophone configured to generate an electrical signal in response to receiving a pressure wave in the liquid of a pool, and a processor configured to receive the electrical signal and generate a trigger signal, when the electrical signal includes a characteristic signature over a time period within a predetermined range of time periods.

Abstract: A pool monitoring system includes a hydrophone configured to generate an electrical signal in response to receiving a pressure wave in the liquid of a pool, and a processor configured to receive the electrical signal and generate a trigger signal, when the electrical signal includes a characteristic signature over a time period within a predetermined range of time periods.

Abstract: A pool monitoring system includes a hydrophone configured to generate an electrical signal in response to receiving a pressure wave in the liquid of a pool, and a processor configured to receive the electrical signal and generate a trigger signal, when the electrical signal includes a characteristic signature over a time period within a predetermined range of time periods.

Abstract: A pool monitoring system includes a hydrophone configured to generate an electrical signal in response to receiving a pressure wave in the liquid of a pool, and a processor configured to receive the electrical signal and generate a trigger signal, when the electrical signal includes a characteristic signature over a time period within a predetermined range of time periods.

Abstract: This disclosure relates to a novel apparatus for perforating the necks of aerosol containers by providing an aerosol end for two or three piece containers having an annular shoulder joined by a radius to a cylindrical neck closed by an end wall, positioning the neck in exterior telescopic relationship to a punch having a circumferential axially terminal cutting edge, supporting the aerosol end in its telescoped position by seating of the end wall upon an end face of the punch, providing an annular guide ring with an internal diameter corresponding generally to the outer diameter of the neck, disposing the axes and imparting relative telescopic movement between the punch and guide ring to sever by a ripping action under tension the end wall from the cylindrical neck while at the same time sandwiching the latter between the inner and outer diameters of the ring guide and punch, respectively.