If you plan to store your Optima CM without use for an extended period of time there are several steps you should take to protect the unit.
First, remove all batteries from the unit. This includes the AA battery in the Petrel 3 controller, the 9V battery in the SOLO/solenoid external canister, and the AA battery in the OBOE/HUD external canister.
There is a slight current draw on the batteries even when the unit is turned off. Also, alkaline batteries tend to leak when they are fully discharged.
You will want to perform a thorough cleaning and sterilization of the entire breathing loop and then allow it to dry completely in pieces before storage.
Store all pieces in a sealed box and/or a plastic bag to keep bugs from getting inside of the components.
The unit should be stored in a cool, dry environment away from direct sunlight.
It is not recommended to remove the oxygen sensors for storage. However, all sensor dates should be inspected after a long period of storage to ensure that they have not expired. Replace any expired sensors, install fresh batteries, and perform a sensor calibration before diving the unit.