A powder dosing valve is a mechanical device (sometimes also called a ‘butterfly valve’) that delivers a precise amount of powder when filling bags, drums, boxes or other containers. It can used for pharmaceutical ingredients, corrosive powders or agents, abrasive powders, for example, or in any other application where an extremely precise amount of a given item needs to be measured when moving it from a larger container to a smaller one. Typical dosing valves provide accuracy within plus or minus 20g but some can be as accurate as plus or minus 1g.
These types of valve are generally based on a butterfly valve design. Butterfly valves have largely replaced ball valves because they cost less, are lighter weight and provide more accurate measures. These types of valves have been in use since the 18th century when they were invented by James Watt in his steam engine prototypes.