All your employees should input inventory and order data into your computer system in real time. The computer database should tell the inside guy how many valves are in stock (no waiting). The warehouse should learn about orders the instant they are placed. This will involve training and procedures.
This is a pretty straightforward process: A valve arrives in a box from a vendor. It gets unpacked in a receiving area. Then the valve gets put away in the warehouse. Ultimately it gets picked, and is probably put in a staging area. It gets packed and then the packed order is moved to a shipping area.