Section 811.61. General.

  The department may approve the use of hydro-pneumatic, or pressure, tanks, as provided in s. NR 811.62 (2) . All of the following requirements shall be met:

(1)  The tanks shall be completely housed, or earth-mounded with one end projecting into an operating house, to prevent freezing. A tank may be installed below grade if one end is exposed in a basement, vault or manhole. If the tank is installed below grade, all electrical controls and air release valves and any other appurtenances which may permit contamination of the water supply shall be extended to at least 24 inches above grade. Air release piping extended above grade shall be terminated in a down-turned U-bend screened with a 24-mesh corrosion resistant screen. The basement, vault or manhole shall be constructed to prevent surface water from entering including sealing any annular spaces where pipes and appurtenances pass through a wall, floor or ceiling. The basement, vault or manhole shall be equipped with heating, ventilation and dehumidification equipment if necessary to prevent excessive corrosion of the pressure tank and associated piping or to prevent water from freezing. Access manholes shall terminate a minimum of 24 inches above grade with an overlapping, locking cover. Vent pipes shall be metal and terminate a minimum of 24 inches above grade in a downward facing U-bend screened with a 24-mesh corrosion resistant screen. Doors shall open outward and be provided with a lock.

(2)  Each tank shall be provided with bypass piping and the necessary shut-off valves to permit operation of the system while the tank is being repaired or painted. For galvanized or bladder type pressure tanks, the individual connecting pipe to each tank shall be provided with a shut-off valve, pipe union and drain fitting. Threaded drain fittings shall be provided with a vacuum breaker.

(3)  Each tank not equipped with a bladder or diaphragm to separate the air and water and with a gross volume of 500 gallons or more shall have a drain fitting with shut-off valve and control equipment consisting of a pressure gauge, a pressure relief valve, a water sight glass, an automatic air blow-off, and pressure or probe operated start-stop controls for the pumps.

(4)  Each tank not equipped with a bladder or diaphragm to separate the air and water and with a gross volume of 500 gallons or more or that will be painted inside shall be provided with an access manhole. If the tank interior is to be painted it shall be painted with NSF/ANSI approved paints in accordance with s. NR 810.09 (5) .

(5)  Each tank not equipped with a bladder or diaphragm to separate the air and water and with a gross volume of 500 gallons or more shall be provided with an automatically controlled air compressor to add air to the tank. All compressors used to routinely add air to tanks shall be oil-less. Larger capacity compressors that are not oil-less may be used temporarily to fill a tank upon startup, repair or service but shall be fitted with one or more filters and any other appurtenances necessary to remove particulates and oil from the air prior to injection.

(6)  Each tank equipped with a diaphragm or bladder shall be equipped with an air inlet for adding air manually, a pressure relief valve for each tank or bank of tanks sized to handle the maximum flow rate, and pressure-operated start up and shut down controls for the well pump.

(7)  The gross volume, in gallons, of any tank or combination of tanks, shall be at least 10 times the capacity of the largest pump, rated in gallons per minute, unless the proposed pump motor or motors will be controlled by a variable output control device in a manner intended to reduce the volume of required pressure tank storage in accordance with s. NR 811.34 (6) . For a standard installation, the required storage volume is intended to provide a minimum pump run time of 2 to 3 minutes.

(8)  Each tank shall be identified by stamping or labeling showing the manufacturer's name, a serial number, the tank volume, the allowable working pressure, and the year fabricated.

(9)  Each tank not equipped with a bladder or diaphragm to separate the air and water and with a gross volume of 500 gallons or more shall be constructed of steel and have a 0.25 inch minimum side wall and head wall thickness.

History: CR 09-073 : cr. Register November 2010 No. 659 , eff. 12-1-10.