Page 31 - 2018_IMC

DEFINITIONS

FLUE LINER (LINING). A system or material used to form HIGH-PROBABILITY SYSTEMS. A refrigeration system
the inside surface of a flue in a chimney or vent, for the pur- in which the basic design or the location of components is
pose of protecting the surrounding structure from the effects such that a leakage of refrigerant from a failed connection,
of combustion products and conveying combustion products seal or component will enter an occupancy classified area,
without leakage to the atmosphere. other than the machinery room.
FOOD-GRADE FLUID. Potable water or a fluid containing HIGH-SIDE PRESSURE. The parts of a refrigerating sys-
additives listed in accordance with the Code of Federal Regu- tem subject to condenser pressure.
lations, Title 21, Food and Drugs, Chapter 1, Food and Drug
Administration, Parts 174-186. HIGH-VOLUME, LARGE-DIAMETER FAN. A low-
speed ceiling fan that circulates large volumes of air and that
[FG] FUEL GAS. A natural gas, manufactured gas, liquefied is greater than 7 feet (2134 mm) in diameter.
petroleum gas or a mixture of these.
HOOD. An air intake device used to capture by entrapment,
FUEL OIL. Kerosene or any hydrocarbon oil having a flash
point not less than 100ºF (38ºC). impingement, adhesion or similar means, grease, moisture,
heat and similar contaminants before they enter a duct sys-
FUEL-OIL PIPING SYSTEM. A closed piping system that tem.
connects a combustible liquid from a source of supply to a
fuel-oil-burning appliance. Type I. A kitchen hood for collecting and removing
grease vapors and smoke. Such hoods are equipped with a
FURNACE. A completely self-contained heating unit that is fire suppression system.
designed to supply heated air to spaces remote from or adja-
cent to the appliance location. Type II. A general kitchen hood for collecting and remov-
ing steam, vapor, heat, odors and products of combustion.
FURNACE ROOM. A room primarily utilized for the instal-
lation of fuel-burning, space-heating and water-heating appli- [FG] HYDROGEN GENERATING APPLIANCE. A self-
ances other than boilers (see also “Boiler room”). contained package or factory-matched packages of integrated
FUSIBLE PLUG. A device arranged to relieve pressure by systems for generating gaseous hydrogen. Hydrogen generat-
operation of a fusible member at a predetermined tempera- ing appliances utilize electrolysis, reformation, chemical, or
ture. other processes to generate hydrogen.
GROUND SOURCE HEAT PUMP LOOP SYSTEM. Pip- IGNITION SOURCE. A flame, spark or hot surface capable
ing buried in horizontal or vertical excavations or placed in a of igniting flammable vapors or fumes. Such sources include
body of water for the purpose of transporting heat transfer appliance burners, burner ignitors and electrical switching
liquid to and from a heat pump. Included in this definition are devices.
closed loop systems in which the liquid is recirculated and [F] IMMEDIATELY DANGEROUS TO LIFE OR
open loop systems in which the liquid is drawn from a well or
other source. HEALTH (IDLH). The concentration of airborne contami-
nants that poses a threat of death, immediate or delayed per-
HAZARDOUS LOCATION. Any location considered to be manent adverse health effects, or effects that could prevent
a fire hazard for flammable vapors, dust, combustible fibers escape from such an environment. This contaminant concen-
or other highly combustible substances. The location is not tration level is established by the National Institute of Occu-
necessarily categorized in the International Building Code as pational Safety and Health (NIOSH) based on both toxicity
a high-hazard use group classification. and flammability. It is generally expressed in parts per million
3
HEAT EXCHANGER. A device that transfers heat from by volume (ppm v/v) or milligrams per cubic meter (mg/m ).
one medium to another.
INDIRECT REFRIGERATION SYSTEM. A system in
HEAT PUMP. A refrigeration system that extracts heat from which a secondary coolant cooled or heated by the refrigerat-
one substance and transfers it to another portion of the same ing system is circulated to the air or other substance to be
substance or to a second substance at a higher temperature for cooled or heated. Indirect systems are distinguished by the
a beneficial purpose. following methods of application:
HEAT TRANSFER LIQUID. The operating or thermal Closed system. A system in which a secondary fluid is
storage liquid in a mechanical system, including water or either cooled or heated by the refrigerating system and
other liquid base, and additives at the concentration present then circulated within a closed circuit in indirect contact
under operating conditions used to move heat from one loca- with the air or other substance to be cooled or heated.
tion to another. Refrigerants are not included as heat transfer
liquids. Double-indirect open-spray system. A system in which
the secondary substance for an indirect open-spray system
HEAVY-DUTY COOKING APPLIANCE. Heavy-duty is heated or cooled by an intermediate coolant circulated
cooking appliances include electric under-fired broilers, elec- from a second enclosure.
tric chain (conveyor) broilers, gas under-fired broilers, gas
chain (conveyor) broilers, gas open-burner ranges (with or Open-spray system. A system in which a secondary cool-
without oven), electric and gas wok ranges, smokers, smoker ant is cooled or heated by the refrigerating system and
ovens, and electric and gas over-fired (upright) broilers and then circulated in direct contact with the air or other sub-
salamanders. stance to be cooled or heated.

14 2018 INTERNATIONAL MECHANICAL CODE 
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