In OpenERP, you can handle three types of goods: two types of products (Stockable or Consumable products) and one type of services.

A consumable is a physical product which is treated like a stockable product, with the exception that stock management is not taken into account by the system. You can buy it, deliver it or even produce it but OpenERP will always assume that there is enough of it in stock. It will NEVER trigger a procurement for these types of products, and your stock levels will go negative if the inventory in OpenERP ever gets to 0.

To create consumables, for Product Type, select Consumable