IS 3963-1966

标准号：IS 3963-1966
发布日期：1967/5/1 12:00:00
实施日期：1999/12/31 12:00:00
适用范围：1.1 This standard specifies the requirements and tests for roof extractor units in which the extraction fan is driven by an electric motor operated from either single-phase supply voltage not exceeding 250 volts or three-phase supply voltage not exceeding 440 volts. It covers the following types of roof extractor units:a) 'Vertijet' type in which there are two or more shutters (on the top of the cowl) which open only when the fan is operated and the air leaves the weather-protection casing vertically upwards sub-stantially parallel to the axis of the fan impeller, andb) 'Cowl' type in which the top of the weather-protection casing is closed and the air driven vertically upwards by the fan impeller rebounds from the top of the cowl and leaves the casing down-wards through openings at its sides (see Fig. 1).This standard also covers speed regulators, if any, associated with the extractor fans.1.1.1 This standard does not cover units in which the fan impeller is not directly driven by the motor.