Abstract: A diaphragm-type sensor arrangement to measure the flow pressure in a main pipe. The arrangement includes a connecting line in fluid communication with the main line and a housing with a chamber. The chamber is isolated from fluid communication with the connecting line by a flexible diaphragm and filled with a second fluid. In use, the diaphragm is displaced by pressure changes in the connecting line which in turn displaces the second fluid in the housing chamber to activate a pressure reading device. The sensor arrangement is particularly adapted for use with slurry flows of particulate solids in a liquid carrier and further includes a reaming member to breakup any consolidated plugs or clogs of solid particles in the connecting line.