Wisconsin Administrative Code › Department of Natural Resources › NR 800 - Environmental Protection - Water Supply › Chapter NR 811 - Requirements For The Operation And Design Of Community Water Systems › Subchapter VIII - Hydro-Pneumatic Tanks › Section NR 811.61 - General

Current through June 24, 2024
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
				  maximum pump capacity, 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).
Note:
The department recommends that the
					 storage volume provides a minimum pump run time of at least 2
					 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.