non-return valve, non-return device, retaining valve
a screw-down valve in which the spindle is not fixed to the valve disc or gate, so that while it may press it down on its seat it is incapable of lifting it. As a result the fluid going through the piping system can lift the valve and pass upward, but it cannot return and flow in the other direction. Valve chests for bilge and ballast systems are equipped with non-return valves., isteoimiv klapp, mis tagab vedeliku, auru või gaasi ühesuunalise voolamise; kui voolu suund muutub või vool katkeb, sulgub tagasilöögiklapp automaatselt
