Definitions

Section 201 sets the rules for reading every defined term in the code:

• Terms not defined in this code but defined in other International Codes carry the meaning ascribed to them in those codes.
• Terms not defined anywhere carry their ordinarily accepted meanings as the context implies.
• Tense, gender, and number are flexible: the singular includes the plural and the plural includes the singular.

An appliance is a device designed for a specific purpose that uses fuel gas. Whether it is vented or unvented depends on whether the products of combustion are conveyed directly to the outdoor atmosphere.

• Combustion chamber: the portion of an appliance within which combustion occurs.
• Combustion air: air necessary for complete combustion of a fuel, including theoretical air and excess air.
• Flame Safeguard: a device that automatically shuts off the fuel supply when the means of ignition becomes inoperative.
• Ignition pilot: a pilot that operates during the lighting cycle and discontinues during main burner operation.

Venting terms appear throughout Chapters 5 and 6; knowing their Chapter 2 definitions is essential.

• Venting system: continuous open passageway from the flue collar or draft hood of an appliance to the outdoor atmosphere.
• Natural draft system: a venting system designed to remove flue or vent gases under nonpositive static vent pressure.
• Draft hood: provides for ready escape of flue gases from the appliance in the event of no draft or backdraft.
• Draft Regulator: a device that functions to maintain a desired draft in the appliance by automatically reducing the draft to the desired value.
• Connector, Chimney or Vent: the pipe that connects an appliance to a chimney or vent.
• Factory-built chimney: a listed and labeled chimney composed of factory-made components assembled in the field.

The fuel gas piping system extends from the point of delivery to the appliance shutoff valves. Natural gas and LP-gas systems have different points of delivery.

• Outlet: the point at which a gas-fired appliance connects to the gas piping system.
• System shutoff valve: a valve installed after the point of delivery to shut off the entire piping system.
• Quick-disconnect device: a hand-operated device for connecting and disconnecting an appliance or appliance connector.
• Excess Flow Valve (EFV): activates when the prescribed flow rate of fuel gas is exceeded.
• Makeup air: any combination of outdoor and transfer air intended to replace exhaust air and maintain acceptable indoor air quality.
• Ready Access: enables a device, appliance, or equipment to be directly reached without removing panels or similar obstructions.

A regulator controls and maintains a uniform supply pressure. Several regulator types are defined:

• Service pressure regulator: installed by the serving gas supplier to reduce and limit the service line pressure to delivery pressure.
• Medium-pressure regulator: operates at greater than 0.5 psig and less than or equal to 5 psig.
• Monitoring regulator: a pressure regulator set in series with another pressure regulator for overpressure protection.
• Relief valve: designed to forestall the development of a dangerous condition by relieving either pressure or temperature.
• Dry Gas: a gas having a moisture and hydrocarbon dew point below any normal temperature to which the system is exposed.

• Plastic Heat Fusion Joint: made by heating thermoplastic piping sufficiently to permit fusion of the materials when joined.
• Mechanical joint: obtained by the joining of metal parts through a positive-holding mechanical construction.
• Pressure test: the operational action performed to verify the gastight integrity of gas piping.
• Construction Documents: written, graphic, or pictorial documents describing the design, location, and physical characteristics of a project.
• Third-Party Certification Agency: an approved agency operating a product or material certification program.