Page 34 - 2018_IMC

DEFINITIONS

Tubing. Semirigid conduit of copper, copper-alloy, alumi- directly to a combustible assembly shall not be considered as
num, plastic or steel. part of that combustible assembly.
PLASTIC, THERMOPLASTIC. A plastic that is capable PURGE. To clear of air, water or other foreign substances.
of being repeatedly softened by increase of temperature and PUSH-FIT JOINTS. A type of mechanical joint consisting
hardened by decrease of temperature. of elastomeric seals and corrosion-resistant tube grippers.
PLASTIC, THERMOSETTING. A plastic that is capable Such joints are permanent or removable depending on the
of being changed into a substantially infusible or insoluble design.
product when cured under application of heat or chemical QUICK-OPENING VALVE. A valve that opens com-
means.
pletely by fast action, either manually or automatically con-
PLENUM. An enclosed portion of the building structure, trolled. A valve requiring one-quarter round turn or less is
other than an occupiable space being conditioned, that is considered to be quick opening.
designed to allow air movement, and thereby serve as part of RADIANT HEATER. A heater designed to transfer heat pri-
an air distribution system. marily by direct radiation.
POLLUTION-CONTROL UNIT (PCU). Manufactured READY ACCESS (TO). That which enables a device,
equipment that is installed in a grease exhaust duct system for appliance or equipment to be directly reached, without
the purpose of extracting smoke, grease particles and odors requiring the removal or movement of any panel or similar
from the exhaust flow by means of a series of filters.
obstruction [see “Access (to)”].
PORTABLE FUEL CELL APPLIANCE. A fuel cell gen- RECEIVER, LIQUID. A vessel permanently connected to a
erator of electricity that is not fixed in place. A portable fuel refrigeration system by inlet and outlet pipes for storage of
cell appliance utilizes a cord and plug connection to a grid- liquid refrigerant.
isolated load and has an integral fuel supply.
RECIRCULATED AIR. Air removed from a conditioned
POWER BOILER. See “Boiler.” space and intended for reuse as supply air.
[A] PREMISES. A lot, plot or parcel of land, including any RECLAIMED REFRIGERANTS. Refrigerants repro-
structure thereon.
cessed to the same specifications as for new refrigerants by
PRESS-CONNECT JOINT. A permanent mechanical joint means including distillation. Such refrigerants have been
incorporating an elastomeric seal or an elastomeric seal and chemically analyzed to verify that the specifications have
corrosion-resistant grip ring. The joint is made with a press- been met. Reclaiming usually implies the use of processes or
ing tool and jaw or ring approved by the fitting manufacturer. procedures that are available only at a reprocessing or manu-
PRESSURE, FIELD TEST. A test performed in the field to facturing facility.
prove system tightness. RECOVERED REFRIGERANTS. Refrigerants removed
from a system in any condition without necessarily testing or
PRESSURE-LIMITING DEVICE. A pressure-responsive
mechanism designed to stop automatically the operation of processing them.
the pressure-imposing element at a predetermined pressure. RECYCLED REFRIGERANTS. Refrigerants from which
PRESSURE RELIEF DEVICE. A pressure-actuated valve contaminants have been reduced by oil separation, removal of
or rupture member designed to relieve excessive pressure noncondensable gases, and single or multiple passes through
automatically. devices that reduce moisture, acidity and particulate matter,
such as replaceable core filter driers. These procedures usu-
PRESSURE RELIEF VALVE. A pressure-actuated valve ally are performed at the field job site or in a local service
held closed by a spring or other means and designed to shop.
relieve pressure automatically in excess of the device’s set-
ting. REFRIGERANT. A substance utilized to produce refrigera-
tion by its expansion or vaporization.
PRESSURE VESSELS. Closed containers, tanks or vessels
that are designed to contain liquids or gases, or both, under REFRIGERANT SAFETY CLASSIFICATIONS. Group-
pressure. ings that indicate the toxicity and flammability classes in
accordance with Section 1103.1. The classification group is
PRESSURE VESSELS—REFRIGERANT. Any refriger- made up of a letter (A or B) that indicates the toxicity class,
ant-containing receptacle in a refrigerating system. This does followed by a number (1, 2 or 3) that indicates the flammabil-
not include evaporators where each separate section does not ity class. Refrigerant blends are similarly classified, based on
3
exceed 0.5 cubic foot (0.014 m ) of refrigerant-containing the compositions at their worst cases of fractionation, as sepa-
volume, regardless of the maximum inside dimensions, evap- rately determined for toxicity and flammability. In some
orator coils, controls, headers, pumps and piping. cases, the worst case of fractionation is the original formula-
PROTECTIVE ASSEMBLY (REDUCED CLEAR- tion.
ANCE). Any noncombustible assembly that is labeled or Flammability. See “Flammability classification.”
constructed in accordance with Table 308.4.2 and is placed
between combustible materials or assemblies and mechanical Toxicity. See “Toxicity classification.”
appliances, devices or equipment, for the purpose of reducing REFRIGERATING SYSTEM. A combination of intercon-
required airspace clearances. Protective assemblies attached nected refrigerant-containing parts constituting one closed

2018 INTERNATIONAL MECHANICAL CODE  17
Copyrighted © 2017 by, or licensed to, ICC (ALL RIGHTS RESERVED); licensed to UL, LLC pursuant to License Agreement with ICC. No further reproductions authorized or distribution authorized.
ANY UNAUTHROIZED REPRODUCTION OR DISTRIBUTION IS A VIOLATION OF THE FEDERAL COPYRIGHT ACT AND THE LICENSE AGREEMENT; AND SUBJECT TO CIVIL AND CRIMINAL PENALTIES THEREUNDER.