What is "float valve"

Float \Float\ (fl[=o]t), n.[OE. flote ship, boat, fleet, AS. flota ship, fr. fle['o]tan to float; akin to D. vloot fleet, G. floss raft, Icel. floti float, raft, fleet, Sw. flotta. [root] 84. See Fleet, v. i., and cf. Flotilla, Flotsam, Plover.]

1. Anything which floats or rests on the surface of a fluid, as to sustain weight, or to indicate the height of the liquid surface, or mark the place of, something. Specifically:

   1. A mass of timber or boards fastened together, and conveyed down a stream by the current; a raft.

   2. The hollow, metallic ball of a self-acting faucet, which floats upon the water in a cistern or boiler.

   3. The cork or quill used in angling, to support the bait line, and indicate the bite of a fish.

   4. Anything used to buoy up whatever is liable to sink; an inflated bag or pillow used by persons learning to swim; a life preserver.

   5. The hollow, metallic ball which floats on the fuel in the fuel tank of a vehicle to indicate the level of the fuel surface, and thus the amount of fuel remaining.

   6. A hollow elongated tank mounted under the wing of a seaplane which causes the plane to float when resting on the surface of the water.

      This reform bill . . . had been used as a float by the conservative ministry.
      --J. P. Peters.

2. A float board. See Float board (below).

3. (Tempering) A contrivance for affording a copious stream of water to the heated surface of an object of large bulk, as an anvil or die.
   --Knight.

4. The act of flowing; flux; flow. [Obs.]
   --Bacon.

5. A quantity of earth, eighteen feet square and one foot deep. [Obs.]
   --Mortimer.

6. (Plastering) The trowel or tool with which the floated coat of plastering is leveled and smoothed.

7. A polishing block used in marble working; a runner.
   --Knight.

8. A single-cut file for smoothing; a tool used by shoemakers for rasping off pegs inside a shoe.

9. A coal cart. [Eng.]
   --Simmonds.

10. The sea; a wave. See Flote, n.

11. (Banking) The free use of money for a time between occurrence of a transaction (such as depositing a check or a purchase made using a credit card), and the time when funds are withdrawn to cover the transaction; also, the money made available between transactions in that manner.

12. a vehicle on which an exhibit or display is mounted, driven or pulled as part of a parade. The float often is based on a large flat platform, and may contain a very elaborate structure with a tableau or people.

    Float board, one of the boards fixed radially to the rim of an undershot water wheel or of a steamer's paddle wheel; -- a vane.

    Float case (Naut.), a caisson used for lifting a ship.

    Float copper or Float gold (Mining), fine particles of metallic copper or of gold suspended in water, and thus liable to be lost.

    Float ore, water-worn particles of ore; fragments of vein material found on the surface, away from the vein outcrop.
    --Raymond.

    Float stone (Arch.), a siliceous stone used to rub stonework or brickwork to a smooth surface.

    Float valve, a valve or cock acted upon by a float. See Float, 1 (b) .