1.1 Scope 1.1.1 This standard applies to newly produced, direct gas-fired industrial air heaters, hereinafter referred to as heaters, whose purpose is to offset building heat loss. Ventilation air to the heater shall be ducted directly from outdoors and the products of combustion generated by the heater are released into the air stream being heated. Heaters covered by this standard are intended for use in industrial and commercial applications. This standard applies to heaters designed for heated discharge air temperature of 160°F (71°C). This standard is intended to cover only complete packaged heaters with integral air moving components, i.e., those which are de signed by, cataloged by and built on a repetitive basis by the manufacturer. 1.1.2 Inside air may be introduced before or after the combustion zone. 1.1.3 Outside ventilation air is required to the heater. See 1.22-f, 1.22-n, and 1.23.2-u. 1.1.4 If a value for measurement as given in this standard is followed by an equivalent value in other units, the first stated value is to be regarded as the specification. 1.1.5 All references to psi throughout this standard are to be considered gage pressure unless otherwise specified. 1.1.6 Exhibit A, Electrical Equipment and Wiring, formerly 1.18. 1.1.7 Exhibit B, List of Reference Standards, contains a list of standards specifically referenced in this Standard, and sources from which they may be obtained.