flow meter is a device that is use to measurement is an integral part of process equipment.  right quantity of fluid determine quality of the product. that is why some product taste in a certain way irrespective of where they are made.  having the right quantity of receipt is very important. too much of it can degrade the product quality. which are taste, smell, color etc. flow meter are usually place at the inlet of the process. this ensure the  right quantity is added during blending activities. once the cubic gallon required is attain. the valves close. so basically, not only that flow meter  is pivotal during blending. it is also an important equipment in a control system. the plc need the volumetric count to determine weather to continue  to keep the valve open or close.