粉末裝罐的堵塞形成的可能性取決于粉末的性質和它周圍的條件(濕度、溫度、應力狀態、料斗幾何形狀)。垂直剪切試驗提供了一種方法來測試粉末從填充狀態開始流動，模擬一個充滿的料斗。這種測試也可以幫助確定正確的料斗出口大小的可靠流量。The likelihood of a blockage forming depends on both the properties of the powder and the conditions surrounding it (humidity, temperature, stress state, hopper geometry). A vertical shear test provides a method to test the commencement of flow of a powder from a packed state, imitating a filled hopper. This test can also help to determine the correct hopper outlet size for reliable flow.