D.C. Mun. Regs. tit. 12, r. 12-E1016
Insert a new Section 1016 in the Mechanical Code to read as follows:
Minimum working pressure. Each hydro-pneumatic tank shall be constructed for a minimum working pressure of 150 pounds per square inch (psi) (1034 kPa).
Label. Each hydro-pneumatic tank shall be stamped with the ASME symbol to indicate that it is constructed in accordance with the ASME Code. It shall also be stamped with the name of the manufacturer, the maximum allowable working pressure, the year built and the identifying number of the National Board.
Manufacturer's data report. Applications for permits shall be accompanied by the manufacturer's data report, which shall be signed by an inspector licensed by the National Board to inspect boilers and pressure vessels.
Gauges and manhole. Each hydro-pneumatic tank shall be provided with a gauge-glass to show the level of the water in the upper section of the tank, and a pressure gauge. The tank shall also be provided with an 11-inch (280 mm) manhole opening, which shall be kept clear of walls, pipes or other obstructions.
Safety relief valve. Each hydro-pneumatic tank shall be equipped with a lever lifting safety valve bearing the ASME symbol, suitable for use with air, installed in a vertical position on the top of the tank, and set to relieve at or below the maximum allowable working pressure of the tank. The valve shall be sealed to prevent tampering and there shall be no shut-off valve between the tank and the relief valve.
Pressure gauge. Each hydro-pneumatic tank shall be provided with a pressure gauge not less than 4 inches (102 mm) in diameter connected directly to the tank by means of non-ferrous pipe. A cock with a "tee" handle shall be placed in the pipe near the gauge. The gauge shall be graduated to not less than 1.5 times the maximum allowable working pressure of the tank.
Valve by-pass. Each hydro-pneumatic tank shall be piped to include a full- size valved by-pass so that domestic water can be used in the building when the tank is not in service.
Vacuum relieving device. Each hydro-pneumatic tank shall be provided with a vacuum relieving device located on the top of the tank, and a horizontal swing check valve in the water supply line from the pump to the tank, and in the domestic water supply by-pass line to the tank. A valved sludge drain pipe shall be installed at the bottom of the tank and it shall discharge through an air break into the drainage system of the building.
D.C. Mun. Regs. tit. 12, r. 12-E1016