North Carolina Administrative Code › Title 15A - Environmental Quality › Chapter 18 - ENVIRONMENTAL HEALTH › Subchapter A - SANITATION › Section .2500 - PUBLIC SWIMMING POOLS › Section 18A .2518 - CIRCULATION SYSTEM

Current through Register Vol. 39, No. 2, July 15, 2024
(a) Pools shall be equipped with a
				  circulation system.
(b) The
				  capacity of the circulation system shall be sufficient to clarify and disinfect
				  the entire volume of swimming pool water four times in 24 hours. The system
				  shall be operated 24 hours per day during the operating season.
(c) The circulation piping shall be designed
				  and installed with the necessary valves and pipes so that the flow from the
				  swimming pool can be from main drains or the surface overflow system. The
				  circulation piping shall be designed such the flow of water from the swimming
				  pool can be simultaneous from the surface overflow system and the main drains.
				  Skimmer piping constructed after May 1, 2010 shall be sized to handle the
				  maximum flow rate for the required number of skimmers, but in no case less than
				  100 percent of the design flow rate. Perimeter overflow system piping
				  constructed after May 1, 2010 shall be sized to handle 100 percent of the
				  design flow rate. The main drain piping constructed after May 1, 2010 shall be
				  sized to handle 100 percent of the design flow rate.
(d) Piping shall be designed to reduce
				  friction losses to a minimum and to carry the required quantity of water at a
				  maximum velocity not to exceed six feet per second for suction piping and not
				  to exceed 10 feet per second for discharge piping except for copper pipe where
				  the velocity shall not exceed eight feet per second. Piping shall be of
				  non-toxic material, resistant to corrosion, and able to withstand operating
				  pressures. If plastic pipe is used, a minimum of Schedule 40 PVC is required.
				  Flexible pipe shall not be used except that flexible PVC hoses that meet NSF
				  Standard 50 may be affixed to spa shells where rigid pipes do not provide the
				  necessary angles to connect circulation components. Exposed pipes and valves
				  shall be identified by a color code or labels.
(e) The circulation system shall include a
				  strainer to prevent hair, lint, and other debris from reaching the pump. A
				  spare basket shall be provided. Strainers shall be corrosion-resistant with
				  openings not more than ¼ inch (6.4 mm) in size that provide a free flow
				  area at least four times the cross-section area of pump suction line and are
				  accessible for daily cleaning.
(f)
				  A vacuum cleaning system shall be provided to remove debris and foreign
				  material that settles to the bottom of the swimming pool. Where provided,
				  integral vacuum ports shall be located on the pool wall at least six inches and
				  no greater than 18 inches below the water level. Skimmer vacuums may be used in
				  pools with two or fewer skimmers provided the skimmer basket remains in place
				  while the vacuum is in operation. Integral vacuum cleaning systems shall be
				  provided with valves and protective caps. Integral vacuum ports constructed
				  after May 1, 2010 shall have self-closing caps designed to be opened with a
				  tool.
(g) A rate-of-flow indicator,
				  reading in liters or gallons per minute, shall be installed on the filtered
				  water line and located so that the rate of circulation is indicated. The
				  indicator shall be capable of measuring flows that are at least 1½ times
				  the design flow rate, shall be accurate within 10 per cent of true flow, and
				  shall be easy to read. The indicator shall be installed in accordance with
				  manufacturers' specifications.
(h)
				  A pump or pumps shall be provided with capacity to recirculate the swimming
				  pool water four times in 24 hours, and shall be so located as to eliminate the
				  need for priming. If the pump or pumps, or suction piping is located above the
				  overflow level of the pool, the pump or pumps shall be self-priming. The pump
				  or pumps shall be capable of providing a flow adequate for the backwashing of
				  filters. Unless headloss calculations are provided by the designing engineer,
				  pump design shall be based on an assumed total dynamic head of 65 feet of
				  water. Pumps three horsepower or smaller shall be NSF International (NSF)
				  listed or verified by an independent third-party testing laboratory to meet all
				  applicable provisions of NSF/ANSI Standard 50 which is incorporated by
				  reference including any subsequent amendments or editions. Copies may be
				  obtained from NSF International, P.O. Box 130140, Ann Arbor, MI 48113-0140 at a
				  cost of one hundred fifty-five dollars ($155.00). Verification shall include
				  testing and in-plant quality control inspections. Larger pumps for which NSF
				  listing is not available shall be approved by the Department on a case-by-case
				  basis.
(i) Inlets.
(1) Inlets shall be provided and arranged to
				  produce a uniform circulation of water and maintain a uniform disinfectant
				  residual throughout the pool.
(2)
				  The number of inlets for any swimming pool shall be determined based on return
				  water flow. There shall be at least one inlet per 20 gallons per minute of
				  return water flow. There shall be a minimum of four inlets for any swimming
				  pool.
(3) Inlets shall be located
				  so that no part of the swimming pool is more then 25 feet of horizontal
				  distance from the nearest return inlet.
(4) Provision shall be made to permit
				  adjustment of the flow through each inlet, either with an adjustable orifice or
				  provided with replaceable orifices to permit adjustments of the
				  flows.