Abstract: An apparatus for cleaning a differential pressure line in a pressure monitoring system is described. The cleaning apparatus has a first fluid pressure inlet, a second fluid pressure inlet, a flow control, and a means for controlling the flow control. The flow control has a first port in fluid communication with the fluid pressure inlet and a second port in selectable fluid communication with the second fluid pressure inlet and a third port in selectable fluid communication with the first pressure inlet. The means for controlling the flow control allows the flow control to selectively receive a reverse-flow fluid pressure via the second fluid pressure inlet and selectively distribute the reverse-flow fluid pressure to the fluid pressure inlet via the first port.