粉末装罐的堵塞形成的可能性取决于粉末的性质和它周围的条件(湿度、温度、应力状态、料斗几何形状)。垂直剪切试验提供了一种方法来测试粉末从填充状态开始流动，模拟一个充满的料斗。这种测试也可以帮助确定正确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.