– A –
ABS – Acrylonitrile-butadiene-styrene.
Accessible – When applied to a fixture, connection, appliance, or equipment, “accessible” means having access thereto, but which first may require the removal of an access panel, door, or similar obstruction. “Readily accessible” means direct access without the necessity of removing any panel, door, or similar obstruction.
Airbreak – A physical separation which may be a low inlet into the indirect waste receptor from the
fixture, appliance, or device indirectly connected.
Airgap, Drainage – The unobstructed vertical distance through the free atmosphere between the
lowest opening from any pipe, plumbing fixture, appliance, or appurtenance conveying waste to the flood-level rim of the receptor.
Airgap, Water Distribution – The unobstructed vertical distance through the free atmosphere
between the lowest opening from any pipe or faucet conveying potable water to the flood-level rim of any tank, vat, or fixture.
Approved – Acceptable to the Authority Having Jurisdiction.
Approved Testing Agency – An organization primarily established for purposes of testing to
approved standards and approved by the Authority Having Jurisdiction.
Area Drain – A receptor designed to collect surface or storm water from an open area.
Aspirator – A fitting or device supplied with water or other fluid under positive pressure that passes through an integral orifice or constriction, causing a
Authority Having Jurisdiction – The organization, office, or individual responsible for enforcing the
requirements of a code or standard, or for approving equipment, materials, installations, or procedures.
The Authority Having Jurisdiction shall be a federal, state, local, or other regional department or an individual such as a plumbing official, mechanical official,
labor department official, health department official, building official, or others having statutory
authority. In the absence of a statutory authority, the Authority Having Jurisdiction may be some other responsible party. This definition shall include the Authority Having Jurisdiction’s duly authorized representative.
Backflow – The flow of water or other liquids, mixtures, or substances into the distributing pipes of
a potable supply of water from any sources other than its intended source.
Backflow Connection – Any arrangement whereby backflow can occur.
Back-Pressure Backflow – Backflow due to an increased pressure above the supply pressure, which may be due to pumps, boilers, gravity, or other sources of pressure.
Backflow Preventer – A device or means to prevent backflow into the potable water system.
Back-Siphonage – The flowing back of used, contaminated, or polluted water from a plumbing
fixture or vessel into a water supply pipe due to a pressure less than atmospheric in such pipe.
Backwater Valve – A device installed in a drainage system to prevent reverse flow.
Bathroom Group – A group of fixtures consisting of a water closet, one or two lavatories, and either a bathtub, a combination bath/shower, or a shower and may include a urinal or bidet and an emergency floor drain.
Bathroom, Half – A room equipped with only a water closet and lavatory.
Battery of Fixtures – Any group of two (2) or more similar, adjacent fixtures that discharge into a
common horizontal waste or soil branch.
Boiler Blowoff – An outlet on a boiler to permit emptying or discharge of sediment.
Branch – Any part of the piping system other than a main, riser, or stack.
Branch Vent – A vent connecting one (1) or more individual vents with a vent stack or stack vent.
Building – A structure built, erected, and framed of component structural parts designed for the housing, shelter, enclosure, or support of persons, animals, or property of any kind.
Building Drain – That part of the lowest piping of a drainage system that receives the discharge from soil, waste, and other drainage pipes inside the walls of the building and conveys it to the building sewer beginning two (2) feet (610 mm) outside the building
Building Drain (Sanitary) – A building drain that conveys sewage only.
Building Drain (Storm) – A building drain that conveys storm water or other drainage, but no
Building Sewer – That part of the horizontal piping of a drainage system that extends from the end of the building drain and that receives the discharge of the building drain and conveys it to a public sewer, private sewer, private sewage disposal system, or other point of disposal.
Building Sewer (Combined) – A building sewer that conveys both sewage and storm water or other drainage.
Building Sewer (Sanitary) – A building sewer that conveys sewage only.
Building Sewer (Storm) – A building sewer that conveys storm water or other drainage, but no
Building Subdrain – That portion of a drainage system that does not drain by gravity into the
Building Supply – The pipe carrying potable water from the water meter or other source of water supply to a building or other point of use or distribution on the lot. Building supply shall also mean water service.
Certified Backflow Assembly Tester – A person who has shown competence to test and maintain
backflow assemblies to the satisfaction of the Authority Having Jurisdiction.
Cesspool – A lined excavation in the ground that receives the discharge of a drainage system or part thereof, so designed as to retain the organic matter and solids discharging therein, but permitting the liquids to seep through the bottom and sides.
Clear Water Waste – Cooling water and condensate drainage from refrigeration and air-conditioning equipment; cooled condensate from steam heating systems; and cooled boiler blowdown water.
Clinic Sink – A sink designed primarily to receive wastes from bedpans and having a flush rim, an integral trap with a visible trap seal, and the same flushing and cleansing characteristics as a water closet.
Code – A standard that is an extensive compilation of provisions covering broad subject matter or that is suitable for adoption into law independently of other codes and standards.
Combination Thermostatic/Pressure Balancing Valve – A mixing valve that senses outlet temperature and incoming hot and cold water pressure and compensates for fluctuations in incoming hot and cold water temperatures and/or pressures to stabilize outlet temperatures.
Combination Waste and Vent System – A specially designed system of waste piping embodying the horizontal wet venting of one or more sinks or floor drains by means of a common waste and vent pipe, adequately sized to provide free movement of air above the flow line of the drain.
Common – That part of a plumbing system that is so designed and installed as to serve more than one (1) appliance, fixture, building, or system.
Conductor – A pipe inside the building that conveys storm water from the roof to a storm drain,
combined building sewer, or other approved point of disposal.
Confined Space – A room or space having a volume less than fifty (50) cubic feet per 1,000 Btu/h (1.4 m3/293 W) of the aggregate input rating of all fuel burning appliances installed in that space.
Contamination – An impairment of the quality of the potable water that creates an actual hazard to the public health through poisoning or through the spread of disease by sewage, industrial fluids, or waste. Also defined as High Hazard.
Continuous Vent – A vertical vent that is a continuation of the drain to which it connects.
Continuous Waste – A drain connecting the compartments of a set of fixtures to a trap or
connecting other permitted fixtures to a common trap.
CPVC – Chlorinated Poly (Vinyl Chloride).
Critical Level – The critical level (C-L or C/L) marking on a backflow prevention device or vacuum
breaker is a point conforming to approved standards and established by the testing laboratory (usually stamped on the device by the manufacturer) that determines the minimum elevation above the flood level rim of the fixture or receptor served at which the device may be installed. When a backflow prevention device does not bear a critical level marking, the bottom of the vacuum breaker, combination valve, or the bottom of any such approved device shall constitute the critical level.
Cross-Connection – Any connection or arrangement, physical or otherwise, between a potable water supply system and any plumbing fixture or any tank, receptor, equipment, or device, through which it may be possible for nonpotable, used, unclean, polluted, and contaminated water, or other substances to enter into any part of such potable water system under any condition.
– D –
Department Having Jurisdiction – The Authority Having Jurisdiction, including any other law
enforcement agency affected by any provision of this code, whether such agency is specifically named or not.
Design Flood Elevation – The elevation of the “design flood,” including wave height, relative to the
datum specified on the community’s legally designated flood hazard map.
Developed Length – The length along the center line of a pipe and fittings.
Diameter – Unless specifically stated, “diameter” is the nominal diameter as designated commercially.
Domestic Sewage – The liquid and water-borne wastes derived from the ordinary living processes, free from industrial wastes, and of such character as to permit satisfactory disposal, without special treatment, into the public sewer or by means of a private sewage disposal system.
Downspout – The rain leader from the roof to the building storm drain, combined building sewer, or other means of disposal located outside of the building. See Conductor and Leader.
Drain – Any pipe that carries waste or waterborne wastes in a building drainage system.
Drainage System – Includes all the piping within public or private premises that conveys sewage or other liquid wastes to a legal point of disposal, but does not include the mains of a public sewer system or a public sewage treatment or disposal plant.
Durham System – A soil or waste system in which all piping is threaded pipe, tubing, or other such
rigid construction, using recessed drainage fittings to correspond to the types of piping.
Effective Opening – The minimum cross-sectional area at the point of water supply discharge measured or expressed in terms of (1) diameter of a circle or (2) if the opening is not circular, the diameter of a circle of equivalent cross-sectional area. (This is applicable
also to airgap.)
Essentially Nontoxic Transfer Fluid - Essentially nontoxic at practically nontoxic, Toxicity Rating Class 1 (reference "Clinical Toxicology of Commercial
Products" by Gosselin, Smith, Hodge, & Braddock).
Excess Flow Valve (EFV) – A valve designed to activate when the fuel gas passing through it exceeds a prescribed flow rate.
Existing Work – A plumbing system or any part thereof that has been installed prior to the effective
date of this code.
– F –
Fixture Branch – A water supply pipe between the fixture supply pipe and the water distributing pipe.
Fixture Drain – The drain from the trap of a fixture to the junction of that drain with any other drain pipe.
Fixture Supply – A water supply pipe connecting the fixture with the fixture branch.
Fixture Unit – A quantity in terms of which the load producing effects on the plumbing system of different kinds of plumbing fixtures are expressed on some arbitrarily chosen scale.
Flammable Vapor or Fumes – The concentration of flammable constituents in air that exceeds 25 percent of its lower flammability limit (LFL).
Flood Hazard Area – The greater of the following two areas:
(1) The area within a floodplain subject to a one (1) percent or greater chance of flooding in any
(2) The area designated as a flood hazard area on a community’s flood hazard map, or
otherwise legally designated.
Flood Hazard Area Subject to High Velocity Wave Action – Area within the flood hazard area that is subject to high velocity wave action, and shown on a Flood Insurance Rate Map or other flood hazard map as Zone V, VO, VE or V1-30.
Flood-Level Rim – The top edge of a receptor from which water overflows.
Flooded – A fixture is flooded when the liquid therein rises to the flood-level rim.
Flush Tank – A tank located above or integral with water closets, urinals, or similar fixtures for the
purpose of flushing the usable portion of the fixture.
Flush Valve – A valve located at the bottom of a tank for the purpose of flushing water closets and
Flushometer Tank – A tank integrated within an air accumulator vessel that is designed to discharge a predetermined quantity of water to fixtures for
Flushometer Valve – A valve that discharges a predetermined quantity of water to fixtures for flushing purposes and is actuated by direct water pressure.
FOG Disposal System – A grease interceptor that reduces nonpetroleum fats, oils, and grease (FOG) in effluent by separation,mass and volume reduction.
– G –
Gang or Group Shower – Two (2) or more showers in a common area.
Grade – The slope or fall of a line of pipe in reference to a horizontal plane. In drainage, it is usually expressed as the fall in a fraction of an inch (mm) or percentage slope per foot (meter) length of pipe.
Gravity Grease Interceptor – A plumbing appurtenance or appliance that is installed in a sanitary drainage system to intercept nonpetroleum fats, oils, and greases (FOG) from a wastewater discharge and is identified by volume, thirty (30) minute retention time, baffle(s), not less than two (2) compartments, a total volume of not less than three-hundred (300) gallons,
and gravity separation. [These interceptors comply with the requirements of Chapter 10 or are designed by a registered professional engineer.] Gravity grease interceptors are generally installed outside.
Grease Interceptor – A plumbing appurtenance or appliance that is installed in a sanitary drainage
system to intercept nonpetroleum fats, oil, and greases (FOG) from a wastewater discharge.
Grease Removal Device (GRD) – Any hydromechanical grease interceptor that automatically,
mechanically removes non-petroleum fats, oils and grease (FOG) from the interceptor, the control of which are either automatic or manually initiated.
– H –
Horizontal Branch – A drain pipe extending laterally from a soil or waste stack or building drain with or without vertical sections or branches, which receives the discharge from one (1) or more fixture drains and conducts it to the soil or waste stack or to the building drain.
Horizontal Pipe – Any pipe or fitting that is installed in a horizontal position or which makes an angle of less than forty-five (45) degrees with the horizontal.
Hot Water – Water at a temperature exceeding or equal to 120°F (49°C).
House Drain – See Building Drain.
House Sewer – See Building Sewer.
Hydromechanical Grease Interceptor – A plumbing appurtenance or appliance that is installed
in a sanitary drainage system to intercept nonpetroleum fats, oil, and grease (FOG) from a
wastewater discharge and is identified by flow rate, and separation and retention efficiency. The design incorporates air entrainment, hydromechanical separation, interior baffling, and/or barriers in combination or separately, and one of the following:
A – External flow control, with air intake (vent): directly connected
B – External flow control, without air intake (vent): directly connected
C – Without external flow control, directly connected
D – Without external flow control, indirectly connected
[These interceptors comply with the requirements of
Table 10-2.] Hydromechanical grease interceptors are
generally installed inside.
– I –
Indirect Waste Pipe – A pipe that does not connect directly with the drainage system but conveys liquid wastes by discharging into a plumbing fixture, interceptor, or receptacle that is directly connected to the drainage system.
Individual Vent – A pipe installed to vent a fixture trap and that connects with the vent system above the fixture served or terminates in the open air.
Industrial Waste – Any and all liquid or waterborne waste from industrial or commercial
processes, except domestic sewage.
Insanitary – A condition that is contrary to sanitary principles or is injurious to health.
Conditions to which “insanitary” shall apply include the following:
(1) Any trap that does not maintain a proper trap seal.
(2) Any opening in a drainage system, except where lawful, that is not provided with an
approved liquid-sealed trap.
(3) Any defective fixture, trap, pipe, or fitting.
(4) Any trap, except where in this code exempted, directly connected to a drainage system, the seal of which is not protected against siphonage and back-pressure by a vent pipe.
(5) Any connection, cross-connection, construction, or condition, temporary or permanent, that would permit or make possible by any means whatsoever for any unapproved foreign matter to enter a water distribution system used for domestic purposes.
(6) The foregoing enumeration of conditions to which the term “insanitary” shall apply, shall
not preclude the application of that term to conditions that are, in fact, insanitary.
Interceptor (Clarifier) – A device designed and installed so as to separate and retain deleterious,
hazardous, or undesirable matter from normal wastes and permit normal sewage or liquid wastes to discharge into the disposal terminal by gravity.
Invert – The lowest portion of the inside of a horizontal pipe.
– J –
Joint, Brazed – Any joint obtained by joining of metal parts with alloys that melt at temperatures
exceeding 840°F (449°C), but less than the melting temperature of the parts to be joined.
Joint, Soldered – A joint obtained by the joining of metal parts with metallic mixtures or alloys that melt at a temperature up to and including 840°F (449°C).
– L –
Labeled – Equipment or materials bearing a label of a listing agency (accredited conformity assessment body). See Listed (third-party certified).
Lavatories in Sets – Two (2) or three (3) lavatories that are served by one (1) trap.
Leader – An exterior vertical drainage pipe for conveying storm water from roof or gutter drains.
Liquid Waste – The discharge from any fixture appliance, or appurtenance in connection with a
plumbing system that does not receive fecal matter.
Listed (Third-party certified) – Equipment or materials included in a list published by a listing agency (accredited conformity assessment body) that maintains periodic inspection on current production of listed equipment or materials and whose listing states either that the equipment or material complies with approved standards or has been tested and found suitable for use in a specified manner.
Listing Agency – An agency accredited by an independent and authoritative conformity assessment body to operate a material and product listing and labeling (certification) system and that is accepted by the Authority Having Jurisdiction, which is in the
business of listing or labeling. The system includes initial and ongoing product testing, a periodic
inspection on current production of listed (certified) products, and makes available a published report of such listing in which specific information is included that the material or product conforms to applicable standards and found safe for use in a specific manner.
Lot – A single or individual parcel or area of land legally recorded or validated by other means acceptable to the Authority Having Jurisdiction on which is situated a building or which is the site of any work regulated by this code, together with the yards, courts, and unoccupied spaces legally required for the building or works, and that is owned by or is in the lawful possession of the owner of the building or works.
– M –
Macerating Toilet System – A system comprised of a sump with macerating pump and with connections for a water closet and other plumbing fixtures, which is designed to accept, grind, and pump wastes to an approved point of discharge.
Main – The principal artery of any system of continuous piping to which branches may be connected.
Main Vent – The principal artery of the venting system to which vent branches may be connected.
May – A permissive term.
Mobile Home Park Sewer – That part of the horizontal piping of a drainage system that begins two (2) feet (610 mm) downstream from the last mobile home site and conveys it to a public sewer, private sewer, private sewage disposal system, or other point of disposal.
– N –
Nuisance – Includes, but is not limited to:
(1) Any public nuisance known at common law or in equity jurisprudence.
(2) Whenever any work regulated by this code is dangerous to human life or is detrimental to
health and property.
(3) Inadequate or unsafe water supply or sewage disposal system.
Offset – A combination of elbows or bends in a line of piping that brings one (1) section of the pipe out of line but into a line parallel with the other section.
– P –
PB – Polybutylene.
PE – Polyethylene.
PE-AL-PE – Polyethylene-aluminum-polyethylene.
PEX – Cross-linked polyethylene.
PEX-AL-PEX – Cross-linked polyethylene –aluminumcross- linked polyethylene.
Person – A natural person, his heirs, executor, administrators, or assigns and shall also include a firm, corporation, municipal or quasi-municipal corporation, or governmental agency. Singular includes plural, male includes female.
Pipe – A cylindrical conduit or conductor conforming to the particular dimensions commonly
known as “pipe size.”
Plumbing – The business, trade, or work having to do with the installation, removal, alteration, or repair of plumbing systems or parts thereof.
Plumbing Appliance – Any one (1) of a special class of devices or equipment that is intended to perform a special plumbing function. Its operation and/or control may be dependent upon one (1) or more energized components, such as motors, controls, heating elements, or pressure- or temperature sensing elements. Such device or equipment may operate automatically through one (1) or more of the following actions: a time cycle, a temperature range, a pressure range, a measured volume or weight; or the device or equipment may be manually adjusted or controlled by the user or operator.
Plumbing Appurtenance – A manufactured device, a prefabricated assembly, or an on-the-job assembly of component parts that is an adjunct to the basic piping system and plumbing fixtures. An appurtenance demands no additional water supply, nor does it add any discharge load to a fixture or the drainage system. It performs some useful function in the operation, maintenance, servicing, economy, or safety of the plumbing system.
Plumbing Fixture – An approved-type installed receptacle, device, or appliance that is supplied with water or that receives liquid or liquid-borne wastes and discharges such wastes into the drainage system to which it may be directly or indirectly connected. Industrial or commercial tanks, vats, and similar processing equipment are not plumbing fixtures, but may be connected to or discharged into approved traps or plumbing fixtures when and as otherwise provided for elsewhere in this code.
Plumbing System – Includes all potable water, building supply, and distribution pipes; all
plumbing fixtures and traps; all drainage and vent pipes; and all building drains and building sewers, including their respective joints and connections, devices, receptors, and appurtenances within the property lines of the premises and shall include potable water piping, potable water treating or using equipment, medical gas and medical vacuum systems, liquid and fuel gas piping, and water heaters and vents for same.
Pollution – An impairment of the quality of the potable water to a degree that does not create a
hazard to the public health but which does adversely and unreasonably affect the aesthetic qualities of such potable water for domestic use. Also defined as
Potable Water – Water that is satisfactory for drinking, culinary, and domestic purposes and that
meets the requirements of the Health Authority Having Jurisdiction.
PP – Polypropylene.
Pressure – The normal force exerted by a homogeneous liquid or gas, per unit of area, on the wall of the container.
Static Pressure – The pressure existing without any flow.
Residual Pressure – The pressure available at the fixture or water outlet after allowance is
made for pressure drop due to friction loss, head, meter, and other losses in the system during maximum demand periods.
Pressure-Balancing Valve – A mixing valve that senses incoming hot and cold water pressures and compensates for fluctuations in either to stabilize outlet temperature.
Private or Private Use – Applies to plumbing fixtures in residences and apartments, to private
bathrooms in hotels and hospitals, and to restrooms in commercial establishments where the fixtures are intended for the use of a family or an individual.
Private Sewage Disposal System – A septic tank with the effluent discharging into a subsurface
disposal field, into one (1) or more seepage pits, or into a combination of subsurface disposal field and seepage pit or of such other facilities as may be permitted under the procedures set forth elsewhere in this code.
Private Sewer – A building sewer that receives the discharge from more than one (1) building drain and conveys it to a public sewer, private sewage disposal system, or other point of disposal.
Public or Public Use – Applies to plumbing fixtures that are not defined as private or private use.
Public Sewer – A common sewer directly controlled by public authority.
PVC – Poly(vinyl chloride).
PVDF – Polyvinylidene Fluoride.
– R –
Receptor – An approved plumbing fixture or device of such material, shape, and capacity as to
adequately receive the discharge from indirect waste pipes, so constructed and located as to be readily cleaned.
Regulating Equipment – Includes all valves and controls used in a plumbing system that are required to be accessible or readily accessible.
Relief Vent – A vent, the primary function of which is to provide circulation of air between drainage and vent systems or to act as an auxiliary vent on a specially designed system.
Remote Outlet – When used for sizing water piping, it is the furthest outlet dimension, measuring from the meter, either the developed length of the cold water piping or through the water heater to the furthest outlet on the hot-water piping.
Riser – A water supply pipe that extends vertically one (1) full story or more to convey water to
branches or fixtures.
Roof Drain – A drain installed to receive water collecting on the surface of a roof and to discharge it into a leader, downspout, or conductor.
Roughing-In – The installation of all parts of the plumbing system that can be completed prior to the installation of fixtures. This includes drainage, water supply, gas piping, vent piping, and the necessary fixture supports.
SDR – An abbreviation for “standard dimensional ratio,” which is the specific ratio of the average specified outside diameter to the minimum wall thickness for outside controlled diameter plastic pipe.
Seepage Pit – A lined excavation in the ground which receives the discharge of a septic tank so
designed as to permit the effluent from the septic tank to seep through its bottom and sides.
Septic Tank – A water-tight receptacle that receives the discharge of a drainage system or part thereof, designed and constructed so as to retain solids, digest organic matter through a period of detention, and allow the liquids to discharge into the soil outside of the tank through a system of open joint piping or a seepage pit meeting the requirements of this code.
Sewage – Any liquid waste containing animal or vegetable matter in suspension or solution and that may include liquids containing chemicals in solution.
Sewage Ejector – A device for lifting sewage by entraining it on a high-velocity jet stream, air, or
Sewage Pump – A permanently installed mechanical device, other than an ejector, for removing
sewage or liquid waste from a sump.
Shall – Indicates a mandatory requirement.
Shielded Coupling – An approved elastomeric sealing gasket with an approved outer shield and a tightening mechanism.
Should – Indicates a recommendation or that which is advised but not required.
Single-Family Dwelling – A building designed to be used as a home by the owner of such building, which shall be the only dwelling located on a parcel of ground with the usual accessory buildings.
Slip Joint – An adjustable tubing connection, consisting of a compression nut, a friction ring, and a compression washer, designed to fit a threaded adapter fitting or a standard taper pipe thread.
Soil Pipe – Any pipe that conveys the discharge of water closets, urinals, clinic sinks, or fixtures
having similar functions of collection and removal of domestic sewage, with or without the discharge from other fixtures, to the building drain or building sewer.
Special Wastes – Wastes that require some special method of handling, such as the use of indirect waste piping and receptors, corrosion-resistant piping, sand, oil or grease interceptors, condensers, or other pretreatment facilities.
Stack – The vertical main of a system of soil, waste, or vent piping extending through one (1) or
Stack Vent – The extension of a soil or waste stack above the highest horizontal drain connected to the stack.
Standard – A document, the main text of which contains only mandatory provisions using the
word "shall" to indicate requirements and which is in a form generally suitable for mandatory reference by another standard or code or for adoption into law. Nonmandatory provisions shall be
located in an appendix, footnote, or fine print note and are not to be considered a part of the requirements of a standard.
Storm Sewer – A sewer used for conveying rainwater, surface water, condensate, cooling water, or similar liquid wastes.
Subsoil Drain – A drain that collects subsurface or seepage water and conveys it to a place of disposal.
Sump – An approved tank or pit that receives sewage or liquid waste and which is located below
the normal grade of the gravity system and which must be emptied by mechanical means.
Supports – Supports, hangers, and anchors are devices for properly supporting and securing pipe, fixtures, and equipment.
– T –
Tailpiece – The pipe or tubing that connects the outlet of a plumbing fixture to a trap.
Thermostatic (Temperature Control) Valve – A mixing valve that senses outlet temperature and
compensates for fluctuations in incoming hot or cold water temperatures.
Trap – A fitting or device so designed and constructed as to provide, when properly vented, a liquid seal that will prevent the back passage of air without materially affecting the flow of sewage or wastewater through it.
Trap Arm – That portion of a fixture drain between a trap and the vent.
Trap Primer – A device and system of piping that maintains a water seal in a remote trap.
Trap Seal – The vertical distance between the crown weir and the top dip of the trap.
Crown Weir (Trap Weir) –The lowest point in the cross-section of the horizontal waterway at
the exit of the trap.
Top Dip (of trap) – The highest point in the internal cross-section of the trap at the lowest part of the bend (inverted siphon). By contrast, the bottom dip is the lowest point in the internal cross-section.
– U –
Unconfined Space – A room or space having a volume equal to not less than fifty (50) cubic feet per 1,000 Btu/h (1.4 m3/293 W) of the aggregate input rating of all fuel-burning appliances installed in that space. Rooms communicating directly with the space in which the appliances are installed, through openings not furnished with doors, are considered a part of the unconfined space.
– V –
Vacuum – Any pressure less than that exerted by the atmosphere.
Vacuum Relief Valve – A device that prevents excessive vacuum in a pressure vessel.
Vent – Any pipe provided to ventilate a plumbing system, to prevent trap siphonage and back-pressure, or to equalize the air pressure within the drainage system.
Vent Stack – The vertical vent pipe installed primarily for the purpose of providing circulation of
air to and from any part of the drainage system.
Vent System – A pipe or pipes installed to provide a flow of air to or from a drainage system or to provide a circulation of air within such system to protect trap seals from siphonage and back-pressure.
Vented Flow Control Device – A device installed upstream from the hydromechanical grease interceptor having an orifice that controls the rate of flow through the interceptor, and an air intake (vent) downstream from the orifice, which allows air to be drawn into the flow stream.
Vertical Pipe – Any pipe or fitting that is installed in a vertical position or that makes an angle of not more than 45 degrees with the vertical.
– W –
Wall-Hung Water Closet – A water closet installed in such a way that no part of the water closet touches the floor.
Waste Pipe – A pipe that conveys only liquid waste, free of fecal matter.
Water-Conditioning or Treating Device – A device that conditions or treats a water supply so as to change its chemical content or remove suspended solids by filtration.
Water-Distributing Pipe – In a building or premises, a pipe that conveys potable water from the building supply pipe to the plumbing fixtures and other water outlets.
Water Hammer Arrester – A device designed to provide protection against hydraulic shock in the
building water supply system.
Water Main (Street Main) – A water supply pipe for public or community use.
Water Supply System – The building supply pipe, the water-distributing pipes, and the necessary
connecting pipes, fittings, control valves, backflow prevention devices, and all appurtenances carrying or supplying potable water in or adjacent to the building or premises.
Welded Joint or Seam – Any joint or seam obtained by the joining of metal parts in the plastic molten state.
Welder, Pipe – A person who specializes in the welding of pipes and holds a valid certificate of
competency from a recognized testing laboratory, based on the requirements of the ASME Boiler and Pressure Vessels code, Section IX.
Wet Vent – A vent that also serves as a drain.
Whirlpool Bathtub – A bathtub fixture equipped and fitted with a circulating piping system designed to accept, circulate, and discharge bathtub water upon each use.
Yoke Vent – A pipe connecting upward from a soil or waste stack to a vent stack for the purpose of preventing pressure changes in the stacks.