That would depend on a few factors.
Equipment that is used on a recurring basis for the production of income is a business asset, and it's acquisition by the business is reported in the business assets section. Said equipment is depreciated over time. Most "equipment" is depreciated over 5 years. When you sell that equipment, you report it's disposition in the business assets section.
If equipment is purchased for one time use on a job, that too can be a business asset. Depending on the specifics, it could be considered inventory. But inventory is generally used by a business that is "in the business" of purchasing a product at one price, and selling it at a higher price for a profit.
