Blowoff tanks

1. Blowoff piping from a boiler may not discharge directly into a sewer. A blowoff tank, constructed to the provisions of section VIII of the American Society of Mechanical Engineers Code, must be used where conditions do not provide an adequate and safe open discharge. 2. Blowoff tanks hereinafter installed, if of metal, must be designed for a minimum working pressure of fifty pounds per square inch [344.74 kilopascals]. 3. The outlet from the blowoff tank must be twice the area of the inlet pipe and made to extend internally within eight inches [203.2 millimeters] from the bottom of the tank. 4. Vent pipe at least four times the area of the inlet pipe must lead to the outer atmosphere. 5. Vents must be as direct as possible to the outer air and discharge at a safe location. There may be no valve or other possible obstructions such as water pockets between the tank and the discharge end of the vent pipe. 6. All pipe connections between the tank and the boiler must be as direct as possible and must conform to the American Society of Mechanical Engineers Code. 7. For convenience in cleaning the tank, a manhole or an access opening must be provided. 8. If a blowoff tank is not vented as specified above, it must be constructed for a pressure equal to that allowed on the boiler to which it is attached or must be equipped with a safety valve or valves of sufficient capacity to prevent the pressure from exceeding the safe working pressure of the tank. 9. Boiler blowoff systems constructed in accordance with the national board rules and recommendations for the design and construction of boiler blowoff systems must be considered as complying with this section.