What is "ice pack"

Ice \Ice\ ([imac]s), n. [OE. is, iis, AS. [=i]s; aksin to D. ijs, G. eis, OHG. [=i]s, Icel. [=i]ss, Sw. is, Dan. iis, and perh. to E. iron.]

1. Water or other fluid frozen or reduced to the solid state by cold; frozen water. It is a white or transparent colorless substance, crystalline, brittle, and viscoidal. Its specific gravity (0.92, that of water at 4[deg] C. being 1.0) being less than that of water, ice floats.

   Note: Water freezes at 32[deg] F. or 0[deg] Cent., and ice melts at the same temperature. Ice owes its cooling properties to the large amount of heat required to melt it.

2. Concreted sugar.
   --Johnson.

3. Water, cream, custard, etc., sweetened, flavored, and artificially frozen.

4. Any substance having the appearance of ice; as, camphor ice. Anchor ice, ice which sometimes forms about stones and other objects at the bottom of running or other water, and is thus attached or anchored to the ground. Bay ice, ice formed in bays, fiords, etc., often in extensive fields which drift out to sea. Ground ice, anchor ice. Ice age (Geol.), the glacial epoch or period. See under Glacial. Ice anchor (Naut.), a grapnel for mooring a vessel to a field of ice. --Kane. Ice blink [Dan. iisblink], a streak of whiteness of the horizon, caused by the reflection of light from ice not yet in sight. Ice boat.

   1. A boat fitted with skates or runners, and propelled on ice by sails; an ice yacht.

   2. A strong steamboat for breaking a channel through ice.

      Ice box or Ice chest, a box for holding ice; a box in which things are kept cool by means of ice; a refrigerator.

      Ice brook, a brook or stream as cold as ice. [Poetic]
      --Shak.

      Ice cream [for iced cream], cream, milk, or custard, sweetened, flavored, and frozen.

      Ice field, an extensive sheet of ice.

      Ice float, Ice floe, a sheet of floating ice similar to an ice field, but smaller.

      Ice foot, shore ice in Arctic regions; an ice belt.
      --Kane.

      Ice house, a close-covered pit or building for storing ice.

      Ice machine (Physics), a machine for making ice artificially, as by the production of a low temperature through the sudden expansion of a gas or vapor, or the rapid evaporation of a volatile liquid.

      Ice master. See Ice pilot (below).

      Ice pack, an irregular mass of broken and drifting ice.

      Ice paper, a transparent film of gelatin for copying or reproducing; papier glac['e].

      Ice petrel (Zo["o]l.), a shearwater ( Puffinus gelidus) of the Antarctic seas, abundant among floating ice.

      Ice pick, a sharp instrument for breaking ice into small pieces.

      Ice pilot, a pilot who has charge of a vessel where the course is obstructed by ice, as in polar seas; -- called also ice master.

      Ice pitcher, a pitcher adapted for ice water.

      Ice plow, a large tool for grooving and cutting ice.

n. 1 a large floating mass of ice; pack ice 2 a pack of crushed ice applied to the body in order to reduce pain or inflammation 3 a plastic sac of silicone that can be cooled in a freezer and then used in a cool bag

1. n. a waterproof bag filled with ice: applied to the body (especially the head) to cool or reduce swelling [syn: ice bag]

2. a large expanse of floating ice [syn: pack ice]

An ice pack or gel pack is a portable plastic sac filled with water, or refrigerant gel or liquid. For use the contents are frozen in a freezer. Both ice and other non-toxic refrigerants (mostly water) can absorb a considerable amount of heat before they warm above 0 °C, due to the high latent heat of fusion of water. These packs are commonly used to keep food cool in portable coolers, or as a cold compress to alleviate the pain of minor injuries; or in insulated shipping containers to keep products cool during transport.

Ice packs are used in coolers to keep perishable foods (especially meats, dairy products, eggs, etc.) below the danger zone when outside a refrigerator or freezer, and to keep drinks pleasantly cool. The amount of ice needed varies with the amount of food, its initial temperature, the thermal insulation of the cooler, and the ambient temperature and exposure to direct sunlight. Ice initially well below freezing temperature will last a little longer.

Water has a much higher latent heat of fusion than most substances, and a melting temperature which is convenient and easily attained with, for example, a household freezer. Additives to improve the properties of water are often used. For example, substances can be added to prevent bacterial growth in the pack, or to prevent the water from solidifying so it remains a thick gel throughout use.

Gel packs are often made of non-toxic materials that will remain a slow-flowing gel, and therefore will not spill easily or cause contamination if the container breaks. Gel packs may be made by adding hydroxyethyl cellulose (Cellusize), Sodium polyacrylate, or vinyl-coated silica gel.