alarm valve

alarm valve

[ə′lärm ‚valv]
(engineering)
A device that sounds an alarm when water flows in an automatic sprinkler system.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

wet-alarm valve

A valve that (a) permits the flow of water into a wet-pipe sprinkler system, (b) prevents the reverse flow of water, and (c) incorporates provisions for actuating an alarm under specified flow conditions.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.