pump

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pump¹ / pəmp/ • n. a mechanical device using suction or pressure to raise or move liquids, compress gases, or force air into inflatable objects such as tires: a gas pump. ∎  [in sing.] an instance of moving something or being moved by or as if by such a machine: the pump of blood to her heart. ∎  Physiol. an active transport mechanism in living cells by which specific ions are moved through the cell membrane against a concentration gradient: the bacterium's sodium pump. ∎  a pump-action shotgun. • v. 1. [tr.] force (liquid, gas, etc.) to move in a specified direction by or as if by means of a pump: the blood is pumped around the body| [intr.] if we pump long enough, we should bring the level up. ∎  [intr.] move in spurts as though driven by a pump: blood was pumping from a wound in his shoulder. ∎  fill with something: my veins had been pumped full of glucose. ∎  shoot (bullets) into a target. ∎  (pump something in/into) inf. invest a large amount of money in (something): he pumped all his savings into building the boat. ∎  [tr.] inf. try to elicit information from (someone) by persistent questioning: she began to pump her friend for details. 2. [tr.] move (something) vigorously up and down: we had to pump the handle like mad. ∎  [intr.] move vigorously up and down or back and forth: that's superb running—look at his legs pumping. ∎  apply and release (a brake pedal or lever) several times in quick succession, typically to prevent skidding. ∎  move one's arm as if throwing a ball held in the hand, but without releasing the ball: [in comb.] behind the plate Howard double-pumped then threw to second. PHRASES: pump someone's hand shake a person's hand vigorously. pump iron inf. exercise with weights.PHRASAL VERBS: pump out produce or emit (something) in large quantities or amounts: that little printing press pumped out our brochures for more than twenty years. pump up inflate (a tire, balloon, etc.) ∎ inf. increase: she needs to read and pump up her political grip. ∎  inf. turn up the volume of (music): let's pump up those tunes, man. ∎ inf. give inappropriate support and encouragement to: we let them pump up our egos. pump² • n. a light shoe, in particular: ∎  a woman's plain, lightweight shoe that has a low-cut upper, no fastening, and typically a medium heel. ∎  a man's slip-on patent leather shoe for formal wear.

pump device to lift, transfer, or increase the pressure of a fluid (gas or liquid) or to create a vacuum in an enclosed space by the removal of a gas (see vacuum pumps under vacuum ). The centrifugal pump, the most common kind, consists basically of a rotating device, called an impeller, inside a casing. The fluid to be pumped enters the casing near the shaft of the impeller. Vanes attached to the spinning impeller give the fluid a high velocity so that it can move through an outlet. The reciprocating pump moves a fluid by using a piston that travels back and forth in a cylinder with valves to help control the flow direction. Examples are the lift pump and the force pump. In a lift pump the piston and cylinder are positioned vertically. When the piston moves upward, atmospheric pressure pushes water into the cylinder to fill the empty space beneath the piston. On the downward stroke, the water in the cylinder is forced to flow above the piston. Reversing direction, the piston moves up, allowing more water to come up under it into the cylinder and lifting the water held above it to an outlet pipe where the water flows out of the pump. Since atmospheric pressure will support a column of water no higher than about 33 ft (10 m), a lift pump can raise water no farther than this distance. The rotary pump is like the reciprocating pump in that it allows a fluid to fill a space that then decreases in volume, forcing the fluid out of the space. However, unlike a reciprocating pump, it has no valves and uses one or more rotating components in place of a piston. The jet pump has no moving parts; it uses a swiftly moving fluid to induce motion in another fluid. For example an atomizer, a type of jet pump, uses a high-speed stream of air to pump a liquid, such as a perfume. Compressors are used to pump air or other gases into a closed container. They range from hand pumps to large power-driven devices that furnish compressed air for operating pneumatic machinery and for various other purposes. In nuclear reactors that use liquid radioactive metal, the nonmechanical electromagnetic pump is employed. An electric current is either induced in the liquid metal or is passed through it by electrodes. A magnetic field surrounding the pipe then propels the current-carrying liquid forward.

pump, an essential piece of mechanism on board ship, used for emptying the bilges of any water which may have collected in them. Three types of pumps were fitted in the old sailing vessels to clear the bilges. A small hand-pump, similar to those used ashore, was placed near the mainmast, used when there was only very little water in the bilge and a short spell of pumping would clear it. It was a slow and laborious method. Some ships, particularly Dutch and German ones, used a burr-pump, also known as a bilge pump, in which a spar of wood about 1.8 metres (6 ft) long had a burred end to which a leather was fixed. Two men standing over the pump thrust this down into the box in which the bilge water collected, and six men then hauled it up by a rope fixed to it, thus lifting the water which lay on top of the leather. The third type was the chain-pump, which worked on a similar system to the burr-pump but with an endless motion so that there was no need for men to thrust it down in the bilge-box on each stroke. This was a most efficient pump, and two men working on it could lift a ton of water in 55 seconds. According to Sir Walter Raleigh, it was one of the improvements—bonnets, studsails, anchor capstans, and the ability to strike down a ship's topmast being the others—introduced into the British Navy during his time.

Modern pumps in ships are power driven and are capable of lifting some hundreds of tonnes of water an hour. Most smaller yachts have hand-operated diaphragm pumps which are more efficient than the plunger type. In steamships and their modern equivalents there are many other types of pump, used in connection with their internal machinery, such as fuel pumps to feed the boilers, circulating pumps to draw in seawater for the condensers, feed pumps to return condensed steam to the boilers, trimming pumps to transfer water ballast from one tank to another, and so on.

See also rose box.

pump A device for moving liquids by adding to the pressure existing within them. For example, a centrifugal pump first increases the velocity of the fluid by the use of impellers; this velocity increase is then converted to an increase in pressure by the use of appropriately orientated guide vanes or the use of a volute casing. Other pump types include multistage turbine pumps, jet pumps, positive-displacement pumps, and suction lifts.

pump Device for raising, compressing, propelling or transferring fluids. The lift pump, for raising water from a well, and the bicycle pump are reciprocating (to-and-fro) pumps. In many modern pumps, a rotating impeller (set of blades) causes the fluid to flow. Jet pumps move fluids by forcing a jet of liquid or gas through them.

pump1 mechanical device for raising water, etc. XV. In earliest use naut.; corr. to late MDu. pompe wood or metal pipe, stone conduit, Du. pomp ship's pump, LG. pump(e); the evidence is inadequate to decide whether the word was prior in Eng. or LG.
Hence pump vb. XVI.

pump n. a pump-action shotgun.
v. shoot (bullets) into a target.

pump2 light close-fitting shoe. XVI. of unkn. orig.

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