Fluid treatment system and cleaning apparatus therefor

A fluid treatment device comprising a housing for receiving a flow of fluid, the housing comprising:

• a fluid inlet;
• a fluid outlet;
• a fluid treatment zone disposed between the fluid inlet and the fluid outlet;
• a radiation source assembly disposed in the fluid treatment zone for treatment of the flow of fluid;
• and
• a cleaning apparatus comprising:
• at least one cleaning sleeve in sliding engagement with the exterior of the radiation source assembly;
• a cleaning chamber disposed in the at least one cleaning sleeve in contact with a portion of the exterior of the radiation source assembly and for being supplied with a cleaning solution, the cleaning chamber comprising an opening to an exterior of the cleaning sleeve;
• a pressure equalization member disposed in the opening to provide a seal between the opening and the exterior of the cleaning sleeve, the pressure equalization member being moveable independently of the cleaning sleeve in response to a pressure gradient thereacross;
• and drive means to translate the at least one cleaning sleeve along the exterior of the radiation source assembly.