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 dome for seating in a passage between the inlet and outlet of the valve, and the passage may be surrounded by an annular ridge for contacting the dome. The diaphragm may have one or more ribs for seating against other portions of the body located around the passage. The valve body may include openings or interruptions to permit fluid to flow through the valve, as well as to permit relatively small particulate matter to flow through. The diaphragm may have a first open position and/or a second open position such that the ribs and openings may perform screening functions to block or restrict particulate matter of relatively large size from flowing to the passage between the dome and the valve body.