Patent ID: 8615825

Claim:
A liquid drainage system comprising a drainage receptacle having a liquid outlet; a drainage pipe in liquid communication with said drainage receptacle via said liquid outlet; means for pumping liquid from said drainage receptacle into said drainage pipe via said liquid outlet; and a first liquid level sensor arranged to detect the level of liquid in said drainage receptacle, wherein said first liquid level sensor is arranged to generate a control signal to turn said pumping means on depending on the detected liquid level and to cause said control signal to be communicated to said pumping means, the pumping means being arranged to pump liquid from said drainage receptacle in response to said control signal, and wherein said first liquid level sensor includes non-contact sensing means for detecting the level of liquid in the receptacle, said system further including a second liquid level sensor configured to detect the level of liquid in said drainage pipe, said second liquid level sensor being configured to generate at least one control signal for turning said pumping means off depending on the detected liquid level in said pipe and to cause said at least one control signal to be communicated to said pumping means.