After lye unloading,when remove the pipe,lye will flow to ground and equipment,it is needed to wash in time,and the rinse water can cause pollution.At the same time,the centrifugal pump is easy to leak,leading to splash.So a device was designed to solve the above two kinds of leakage.Lye in the pipe was emptied by high pressure gas;then a vacuum pump was added to control the vacuum degree,adjusting the absolute pressure at the entrance of the centrifugal pump.Finally,a lye uninstall equipment was set up to make experimental research and the final residual phenomenon was explained.This device can be widely used in liquid transportation,not only for lye unloaded,but also for other regular or high corrosive chemical liquid.It has low cost and it is easy to use,green and environmental protection.