[f. SNIFT v.] Snifting valve, a valve through which air may be expelled from the cylinder of a condensing steam-engine. So † snifting clack, pipe.
(a) 1744. Desaguliers, Exp. Philos., II. 474. This is call’d the Snifting Clack, because the Air makes a Noise every time it blows thro’ it, like a Man snifting with a Cold.
1812. Smeaton, Rep., I. 227. The steam, finding a passage at the snifting clack … blows out thereat.
[1873. Evers, Steam & Steam Eng., iii. 50. A valve to preserve the vacuum, which valve, from the peculiar noise it made, was called the snifting valve, or snifting clack.]
(b.) 1759. H. Wood, Pat. Specif. No. 739. 2. If the hot air be driven into the cylinder with a force superior to the pressure of the atmosphere, that force will drive out the condensed air through what is now called the snifting pipe.
(c) 1822. J. Robison, Syst. Mech. Phil., II. 61. The steam from the boiler will immediately rush in, and … will force the air to issue by the snifting-valve.
1846. A. Young, Naut. Dict., 302. The tail-valve, or snifting-valve, is at the opposite side of the air-pump from the condenser.
1878. Thurston, Growth of Steam-Engine, 138–9. A snifting-valve, k, opens when the engine is blown through.
