49. Maintenance .....................................................................................789.1. Product Storage, Inspection and Safety Management..........789.2. Cleaning the Product ..............................................................789.3. Periodic Inspection..................................................................809.3.1. Battery Pre-installation Inspection ........................................809.3.2. Battery Post-installation Inspection.......................................819.4. Disposal...................................................................................829.5. Troubleshooting ......................................................................839.6. Error Codes.............................................................................8410. Optional Items (requiring order) ......................................................8711. Appendix ...........................................................................................8911.1. Principle of Blood Pressure Measurement ............................8911.2. EMC Information.....................................................................91