Patent: Spa Pressure Sensing System Capable of Entrapment Detection 6,390,781

Spa pressure sensing system capable of entrapment detection. Patent 6,390,781

A safety circuit for use with a spa system includes a pressure sensor which generates a signal representative of the pressure in the system. The safety circuit provides a constant current to the pressure sensor. A microcontroller is coupled to receive the signal from the sensor and is configured to store a first pressure level. The microprocessor compares the first pressure level with the subsequently measured pressure level and generates a control signal if the comparison indicates a change in pressure which exceeds a predetermined amount. The control signal is sent to a spa control circuit. An electronically controlled switch is coupled to receive the control signal from the microcontroller and turn electrical power to the pump off in response thereto.