Part 4 Low Pressure Boilers

Control circuits shall be two wire, one side grounded, having a nominal voltage of 150 volts or less. The circuit shall be connected to a branch circuit that can be fused at not more than the value appropriate for the rating of the electrical components included in the circuit. S…

Suitable explosion vents extending to the outside air shall be installed on storage bins, cyclone collectors and piping for central storage systems of pulverized coal. A large and stable pilot flame to insure proper ignition of the pulverized coal shall be provided. Manual igniti…

All controls shall be accessible for normal servicing and adjustment in position and shall be replaceable during normal servicing. Openings in perforated or expanded metal panels, provided over combustion air, circulating air or draft hood relief openings, shall be not less than …

Pilots shall be placed so that their flames may be directly observed with the main burners off and also, unless other means are available for checking their operations, with the main burners on. Pilots shall be installed so that the ignition port and operating mechanism will not …

Lubricants used on valves shall be resistant to the action of liquefied petroleum gases. Manual valve means for turning on and shutting off the gas supply to the pilot burner shall be provided and shall be so located as to be readily accessible. A manual emergency gas shutoff val…

Bent supply piping shall have the bends smoothly made without any appreciable reduction in cross-sectional area and shall have no imperfection occasioned by the bending process. Gas supply piping, tubing and fittings shall be rigidly supported with pipe hooks, metal pipe straps, …

Provisions shall be made to assure a firm support of flue piping either to the draft hood or to the flue outlet if a built-in draft hood is provided. Thermally activated flue dampers and manually operated flue dampers shall not be used. Electrically operated flue dampers manufact…

Except as otherwise specifically provided, the provisions of this Subpart apply to all gas-fired boilers without regard to date of installation.

All gas-fired boilers shall be equipped with adequate flame safeguard devices.

On manually lighted or automatically ignited gas-fired boilers, the pilot or torch shall be proven at a location where it will reliably ignite the main burner before permitting the main burner gas valve to open either automatically or manually by completing an electrical circuit.

Timed trial-for-ignition equipment shall be provided for both the pilot and the main burner. For burners with an input rating of less than 400,000 Btu per hour, the trial-for-ignition period for the pilot on automatically fired boilers shall not exceed 90 seconds. The main burner…

For burners with an input rating less than 400,000 Btu per hour, the main gas valve shall close automatically within 90 seconds after flame failure. For burners with an input rating of 400,000 Btu per hour or more, the electrical circuit to the main fuel valve shall be automatica…