Process of opening and closing of the valve. When open the valve, firstly turn the handwheel to make the plug lifted and separated with the sealed surface, then turn the handle by 90?degree to connect the channel of plug with the channel of valve body. So that the valve is opened. When close the valve, firstly turn the handle by 90 degree to make the channel of plug vertical to the channel of the valve body, then the handwheel to descend the plug, so that the valve is closed.