Abstract: A security system for pools and spas incorporates two distinct sections. The first control means allows for automatic operation and consists of sensors that detect and keep track of the number of adults entering or leaving the pool area and deactivate or activate the second control means of the system. Within the second control means, a motion detector first senses movement of an animate object in the area adjacent to the pool, which then interrupts, for a certain period of time, pool cleaning equipment to allow the aquatic sonic transducer to operate at a more effective sensitivity which senses frequencies characteristic of splashing over other sounds, coupled to circuitry responsive to the same frequencies. When splashing is detected, alarms are activated which then need to be reset.

Abstract: The condition of a gas turbine is monitored by locating a microphone in the air inlet and listening to or recording the sounds detected during certain periods of the machine operating cycle. By proper selection and control of those periods, the operator is enabled to detect rubs or other problems but is not exposed to undesirable noise levels.

Abstract: A wet cooling tower has an encircling exhaust header in communication with the exhaust of a plurality of gas turbines and a plurality of upwardly inclined conduits, which direct the hot exhaust gas tangentially into the cooling tower to increase the temperature and velocity of the moisture laden air flowing therethrough to lift the effluent air into the upper atmosphere and eliminate the plume under many weather conditions.