How to Store a pressure cooker
If like me you use your pressure cooker multiple times a week then simply store your pressure cooker in an easily accessible cupboard with the lid turned upside down, you should remove the gasket from its groove and place it in the lid. By doing this you will prevent any nasty odors or molds building up, this can be a problem especially when you live in warm humid areas.
If you only use your pressure cooker on rare occasions such as once every couple of weeks then its worth taking that little bit more time to ensure your pressure cooker stores well. Add a couple tablespoons of baking powder to the inside of your pot, put the gasket in a zip-lock bag with a tablespoon of baking powder then place it inside the pot and put the lid on. The baking soda will absorb all the odors and moisture.
Long Term Storage
If your not going to use your pressure cooker for a long period of time follow the steps above and put the pressure cooker in a plastic bag, one of your regular kitchen trash bags will do the trick, then place the cooker in a cardboard box and seal it up with tape. Your pressure cooker will be safely stored for however long you need it to be.
Its best if you store your pressure cooker in a cool dry place where prolonged heat will be avoided. When you need to use it again simply wash it first with warm soapy water.