The OPC-N3 does not have any user-serviceable parts. The fan and laser are both chosen to give good lifetimes. The flow path is designed to minimise particle deposition on any internal surfaces of the OPC. The unit must not be opened for cleaning as this may expose the worker to class 3B-laser radiation and could affect the calibration. Careful cleaning with compressed air may be successful but this should be discussed with Alphasense.