The Ontario Building Code | Direct Flush Valves
188.8.131.52. Direct flush Valves
(1) Every direct flush valve shall,
(a) open fully and close positively under service pressure,
(b) complete its cycle of operation automatically,
(c) be provided with a means of regulating the volume of water that it discharges, and
(d) be provided with a vacuum breaker unless the fixtureis designed so that back-siphonage cannot occur.