Abstract: A low-flow diaphragm valve is disclosed having a flexible diaphragm that cooperates with a portion of the valve body to open and close the valve. The diaphragm may have a portion for seating in a passage between the inlet and outlet of the valve and may have one or more ribs for seating against other portions of the body located around the passage. While the valve body may include openings or interruptions to permit fluid and small particulate matter to flow through the valve, the ribs and openings block or restrict particulate matter of relatively large size from flowing to the passage between the diaphragm and the valve body. With this structure, the valve will function even when particulate matter is trapped between one or more of the diaphragm portion that sits in the passage and ribs, on the one hand, and the body on the other hand.