Details test and examination criteria for Category I, Category II, Category III and Category IV low-pressure steam and hot water boilers for use with natural, manufactured and mixed gases, liquefied petroleum gases and LP gas-air mixtures. A low-pressure steam and hot water boiler is defined in the standard as a boiler operating at or below the following pressures or temperatures: steam heating boiler - 15 psi steam pressure; hot water heating or supply boiler - 160 psi water pressure, 250 F water temperature. The standard also covers such boilers equipped with automatic flue damper or vent damper devices.