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Any pressure less than that exerted by the atmosphere.
A type of backflow preventer installed on openings subject to normal atmospheric pressure that prevents backflow by admitting atmospheric pressure through ports to the discharge side of the device. Device which opens when a vacuum occurs to prevent the backward flow of water in a supply line and contamination of the potable water supply.
See MANUAL SHUTOFF VAL VB.
VALVE LUBRICATED PLUG TYPE
A valve of the plug and barrel type provided with means for maintaining a lubricant between the bearing surfaces.
VALVE MAIN BURNER CONTROL
A valve which controls the gas supply to the main burner manifold.
VALVE MANUAL SHUTOFF
A valve (or **) of the plug and barrel type designed for use with gas, operated manually to control or shut off the supply of gas.
A passageway for conveying flue gases from fuel-burning appliances, or their vent connectors, to the outside atmosphere.
That portion of the vent system which connects the gas appliance to the gas vent or chimney.
VENT DAMPER DEVICE, AUTOMATIC
A device intended for installation in the venting system, in the outlet of or downstream of the appliance draft hood, of an individual automatically operated fuel-gas burning appliance and which is designed to automatically open the venting system when the appliance is in operation and to automatically close off the venting system when the appliance is in a standby or shutdown condition.
VENT DAMPER DEVICE, AUTOMATIC Electrically operated
employs electrical energy to control the device.
VENT DAMPER DEVICE, AUTOMATIC Mechanically actuated
dependent for operation upon the direct application or transmission of mechanical energy without employing any type of energy conversion.
VENT DAMPER DEVICE, AUTOMATIC Thermally actuated
dependent for operation exclusively upon the direct conversion of the thermal energy of the vent gases into mechanical energy.
Products of combustion from gas appliances plus excess air plus dilution air in the vent connector, gas vent or chimney above the draft hood or draft regulator.
See "Vent system."
A vertical vent pipe installed primarily for the purpose of providing circulation of air to and from any part of the drainage system.
VENT SYSTEM GAS
A continuous open passageway from the flue collar or draft hood of a gas-burning appliance to the outside atmosphere for the purpose of removing flue or vent gases. A venting system is usually composed of a vent or a chimney and vent connector, if used, assembled to form the open passageway.
VENT SYSTEM SEWER
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 backpressure.
VENTED APPLIANCE Category I
An appliance which operates with a nonpositive vent static pressure and with a vent gas temperature above a value, both measured as specified in the appropriate nationally recognized appliance standard. They can be either draft hood equipped or fan-assisted combustion system appliances.
VENTED APPLIANCE Category II
An appliance which operates with a nonpositive vent static pressure and with a vent gas temperature below a value, both measured as specified in the appropriate nationally recognized appliance standard.
VENTED APPLIANCE Category III
An appliance which operates with a positive vent static pressure and with a vent gas temperature above a value, both measured as specified in the appropriate nationally recognized appliance standard.
VENTED APPLIANCE Category IV
An appliance which operates with a positive vent static pressure and with a vent gas temperature below a value, both measured as specified in the appropriate nationally recognized appliance standard.
VENTED ROOM HEATER
A vented self-contained, free standing, nonrecessed, gas-burning appliance for furnishing warm air to the space in which installed, directly from the heater without duct connections.
VENTED WALL FURNACE (RECESSED HEATER)
A self-contained vented appliance complete with grilles or equivalent, designed for incorporation in or permanent attachment to the structure of a building, mobile home or travel trailer, and furnishing heated air circulated by gravity or by a fan directly into the space to be heated through openings in the casing. Such appliances shall not be provided with duct extensions beyond the vertical and horizontal limits of the casing proper, except that boots not to exceed 10 inches (254 mm) beyond the horizontal limits of the casing for extension through walls of normal thickness may be permitted. Where such boots are provided they shall be supplied by the manufacturer as an integral part of the appliance and tested as such. This definition shall exclude floor furnaces, unit heaters and central furnaces as herein defined.
Any pipe or fitting that makes an angle of 45 degrees (0.79 rad) or more with the horizontal.