Glossary H

High-density polyethylene (HDPE) is described as a rigid, tough and strong resin of natural milky color.

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Hopper refers to a device for temporarily storing dust collected by an air pollution control device.

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Hardware pertains to the physical components of a computer system such as the central processing unit (CPU), memory, disk storage, tape drives, plotters, printers, terminals, digitizers etc.

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Hoist refers to a suspended machinery unit that is used for lifting and lowering a freely suspended (unguided) load; can be powered by hand, air or electricity; lifting medium either chain, wire rope or roller chain.

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Hand-operated is described as requiring hand manipulation for operation ; not automatic or machine-driven; as, a hand-operated winch. The term hand operated is the opposite of automatic or powered. Examples of hand operated machines, devices or equipments are: arbor press which is a hand-operated machine tool, hand-operated grinder to grind meats used by chefs and cooks

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Hydrogen peroxide is described as a valuable non-irritating and non-poisonous antiseptic. It effervesces in the presence of pus due to the liberation of oxygen. Usual strength 10 volumes, i.e. it contains ten times its volume of available oxygen.

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Heat pump (as used in geothermal industry) in which the refrigerant exchanges heat in a heat exchanger with a fluid circulating through an earth connection medium - ground or ground water. The fluid is contained in a variety of loop/pipes configurations depending on the temperature of the ground and the ground area available. Loops may be installed horizontally or vertically in the ground or submersed in a body of water.

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Hand control is described as a mechanical system that allows for operation of both the gas and brake pedals by either hand and is accomplished by means of a combination lever mounted to the steering column.

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