CSA ANSI Z21.91:2017 pdf free download – Ventless firebox enclosures for gas-fired unvented decorative room heaters
Noncombustible material — material that is not capable of being ignited and burned, such as materials consisting entirely of, or a combination of, steel, iron, brick, tile, concrete, slate, asbestos, glass, and plaster. Normal inlet test pressures — those pressures specified for testing purposes at which adjustment of burner ratings and primary air adjustments are made. Orifice — the opening in an orifice spud or other device whereby the flow of gas is limited and through which the gas is discharged. Orifice spud — a removable plug or cap containing an orifice that permits adjustment of the flow of gas by substitution of a spud with a different size orifice. Port — any opening in a burner head through which gas or a gas-air mixture is discharged for ignition. Radiation shield — a separate panel or panels interposed between heating surfaces and jackets to reduce heat losses through radiation. Safety circuit — a circuit or portion thereof involving one or more safety controls in which failure due to grounding, opening, or shorting of any part of the circuit can cause unsafe operation of the controlled appliance. Safety shutoff device — a device that will shut off the gas supply to the controlled burner(s) in the event the source of ignition fails. This device may interrupt the flow of gas to the main burner(s) only, or to the pilot(s) and main burner(s) under its supervision. Secondary air — the air externally supplied to the flame at the point of combustion. Solid-fuel burning fireplace — a fire chamber and hearth constructed of noncombustible material for use with solid fuels and provided with a chimney.
4.3.5 Adequate dielectric shall be interposed between ungrounded current-carrying parts and those external surfaces that can be contacted during the following Method of Test.
Method of Test
When connected to a supply circuit of rated voltage and frequency, the firebox shall be operated as specified in Clause 5.4, Wall, floor, and ceiling temperatures. At the conclusion of the operating period specified, the applicable dielectric test(s) outlined below shall be conducted. During conduct of the dielectric withstand tests, a 500 volt-ampere, or larger transformer, having an essentially sinusoidal output voltage that can be varied shall be used. The applied potential shall be increased gradually from zero until the required test voltage is reached and shall be held at that value for 1 minute. The use of a 500 volt-ampere, or larger transformer, is not necessary if the high potential testing equipment used maintains the specified high potential voltage at the appliance during the test. a) The firebox shall be capable of withstanding, for 1 minute without breakdown, the application of a 60 hertz potential between high-voltage live parts and dead-metal parts, and between live parts of high- and low-voltage circuits. The test potential shall be 1000 volts plus twice rated voltage. b) A low-voltage circuit shall be capable of withstanding, for 1 minute without breakdown, a 60 hertz potential of 500 volts applied between low-voltage live parts of opposite polarity and between low- voltage live parts and dead-metal parts. The dielectric withstand test between low-voltage parts of opposite polarity need not be conducted on the complete assembly if the components have been separately subjected to this test condition. The arrangement of the test circuit shall be such that if the dielectric material breaks down, a positive signal shall be obtained rather than depending upon a visual inspection of the material.