This video shows being plugged but clearing the line by sucking the product back into the first empty hopper. The principle behind it is like a weather system...high pressure runs toward low pressure. Once the tank with zero psi in it is rapidly opened and closed..the product in the high pressure line is drawn back eventually clearing the plug. Yes. Its obviously better not to plug but this product is heavy, dense and has far to go. As one hopper goes empty, product falls in from an adjacent hopper dropping in too much limestone too fast for the line to handle. Watch your gauges. Truckin's the Life when you know how to do it.