3.11A.4.1. Water Circulation Systems (1) In addition to the requirements of this Subsection, the water circulation system of a public spa shall comply with the requirements of Sentences 3.11.8.1.(2), (3), (6), (7), (9), (10), (11), (13) and (20). (2) A public spa shall be equipped with a water circulation system that is capable of filtering, disinfecting and passing the public spa water through the public spa with a turnover period of not more than (a) 30 minutes for a public spa with a volume of water that exceeds 6 m3, (b) 20 minutes for a public spa with a volume of water that exceeds 4 m3 but does not exceed 6 m3, or (c) 15 minutes for a public spa with a volume of water that does not exceed 4 m3. (3) If cartridge-type filters are used for a public spa, the filters shall be a surface-type that is designed for a maximum flow rate of 0.27 L/s/m2 of effective filter area. (4) Except as provided in Sentence (6), every circulation system in a public spa shall be served by a minimum of two suction or gravity outlets (a) that are interconnected to a full size manifold, and (b) except as provided in Sentence (5), that are separated by a clear distance of not less than 900 mm. (5) If compliance with Clause (4) (b) is impracticable because of dimensional restrictions at the bottom of the public spa, the outlets may be located on two different planes of the public spa if (a) at least one of the outlets through which the public spa can be emptied to a full-size manifold is located on the bottom of the public spa, and (b) the bottom of all outlets, other than skimmers, are not more than 75 mm from the floor of the public spa. (6) A circulation system in a factory-built public spa may be served by a built-in suction or gravity outlet with multiple openings that are connected to a full-size manifold. (7) All fittings at or below the water surface that allow water or air or both to be passed to or from the public spa shall be securely held in place by corrosion resistant fastening that requires a tool for removal and is galvanically compatible with the fittings and grilles or covers. (8) Except as provided in Sentence (9), all suction or gravity fittings installed at or below the water line of a public spa shall (a) have a maximum opening of 7 mm in one direction, and (b) be designed so that the flow of water through the openings does not exceed 0.45 m/s. (9) Sentence (8) does not apply to suction and gravity outlets which are equipped with anti-entrapment covers that comply with the requirements of ANSI/ASME A112.19.8M, “Suction Fittings for Use in Swimming Pools, Wading Pools, Spas, Hot Tubs, and Whirlpool Bathtub Appliances”. (10) The calculation of water velocities for the purposes of Clause (8) (b) and Sentences (11) and (12) and the calculation of water flow rates for the purposes of Sentence (9) shall be based on the assumption that all possible sources of suction flow are present at the same time. (11) The water velocity in a suction pipe shall not exceed 1.8 m/s. (12) The water velocity in a pressure pipe shall not exceed (a) 3.0 m/s for plastic piping, and (b) 1.8 m/s for copper piping. (13) Every suction system that serves a public spa shall be equipped with a vacuum relief mechanism which shall include (a) a vacuum release system, (b) a vacuum limit system, or (c) other engineered systems which are designed, constructed and installed to conform to good engineering practice appropriate to the circumstances. (14) Equipment shall be installed to continuously disinfect the water in a public spa by means of a chlorination, hypochlorination or bromination system that is capable of regulating the dosage of chlorine or bromine. (15) If a two-speed pump is utilized for a public spa, the filter and heater shall be sized to accommodate the maximum pump output, without exceeding the manufacturer’s design flow rate of the filter element or heater and without by-passing the filter element. (16) A public spa equipped with hydro-massage jet fittings shall be provided with a timing device (a) that controls the period of operation of the jet pump, and (b) that is placed in a location where the user must exit the public spa to reset the timer. (17) A public spa water heater shall be equipped with an upper limit cut-off device (a) that is independent of the normal public spa water temperature thermostat, and (b) that limits the maximum water temperature of the public spa to 40ºC. (18) A public spa shall be equipped with a water circulation system that is capable of both completely and partially draining and refilling the public spa water. 3.11A.5. Emergency Provisions for All Public Spas