NR 811.39(2)(e)1.1. All electronic positive displacement diaphragm metering pumps shall be provided with a spring-opposed diaphragm type anti-siphon device or a spring opposed diaphragm type anti-siphon and back pressure valve device installed in the discharge piping of the chemical feed pump. The anti-siphon and back pressure functions may be part of a common device or separate devices. Any back pressure valve shall be set to open at a pressure greater than the maximum pressure in the piping or facilities into which the chemical feed pump will discharge. When a back pressure valve is installed on the discharge piping of a chemical feed pump, it shall be preceded by a pressure relief valve and a pressure gauge or other department approved means to verify that the back pressure valve is operating satisfactory. NR 811.39(2)(e)3.3. Peristaltic chemical feed pumps shall be provided with a back pressure valve device installed in the discharge piping of the chemical feed pump in accordance with the requirements under subd. 1. The department may allow exceptions to the requirements under subd. 1. for peristaltic chemical feed pumps when the installation meets all of the following requirements: NR 811.39(2)(e)3.e.e. The chemical injection location is at a point of continuous positive pressure. NR 811.39(2)(e)4.4. The department may be contacted to request approval of an equivalent anti-siphon device or equivalent means of providing anti-siphon protection if the installation of the anti-siphon devices as required in subds. 1. to 3. is not practical given the properties of the chemical to be fed. Adequate justification shall be provided to the department for the request. NR 811.39(2)(f)1.1. Chemical solutions shall be prevented from being siphoned into the water supply. Anti-siphon protection shall be provided by discharging chemicals at points of positive pressure and by providing anti-siphon devices in accordance with par. (e), or through a suitable air gap or other effective means approved by the department. NR 811.39(2)(f)2.2. All chemicals shall be fed downstream of the check valve. Strong acids and bases such as fluorosilicic acid and sodium hydroxide shall be fed downstream of both the check valve and the shut-off valve. NR 811.39 NoteNote: It is recommended that all chemicals be fed downstream of both the check valve and the shutoff valve. If a second shut-off valve is provided downstream of the primary shut-off valve, the point of injection may be between the 2 shut-off valves.
NR 811.39(2)(f)3.3. If chemical feeding is at a location without continuous positive pressure, one of the following installation requirements shall be met to prevent siphoning of chemical solutions: NR 811.39(2)(f)3.a.a. A suitable air gap shall be provided which is at a higher elevation than the chemical solution tank. NR 811.39(2)(f)3.b.b. A dual head feeder with a small break tank located higher than the chemical solution tank shall be provided. NR 811.39(2)(f)3.c.c. A chemical feed pump discharging without any air gap or break box may be approved by the department on a case-by-case basis if the installation is provided with a spring opposed diaphragm type anti-siphon and back pressure valve device. The back pressure valve shall be installed as close as possible to the point of chemical addition. The spring opposed diaphragm type anti-siphon and back pressure valve device shall be installed in accordance with the requirements of par. (e) 1. NR 811.39(2)(g)(g) Makeup water lines. The makeup water supply lines to chemical feed tanks shall be protected from contamination by chemical solutions either by equipping the supply line with backflow or backsiphonage prevention devices, or by providing an air gap between the supply line and the top of the solution tank. NR 811.39(2)(h)(h) Chemical resistance. Materials and surfaces coming in contact with chemicals shall be resistant to the aggressiveness of the chemical solution. NR 811.39(2)(i)(i) Dry chemical feeders. Dry chemical feeders shall meet the following requirements: NR 811.39(2)(i)2.2. Provide effective dissolving and mixing of the chemical in the solution pot and provide gravity feed from solution pots, if possible. NR 811.39(2)(i)3.3. Completely enclose chemicals to prevent emission of dust to the operating room. NR 811.39(2)(j)(j) Direct sewer connections prohibited. No direct connection shall be made between any sanitary or storm sewer and a drain or overflow from any feeder or solution chamber or tank. NR 811.39(3)(3) Location. Chemical feed equipment shall meet the following requirements: NR 811.39(3)(a)(a) Be located near points of application to minimize length of feed lines. NR 811.39(3)(b)(b) Be readily accessible for servicing or repair and observation of operation. NR 811.39(3)(c)(c) Be located and have protective containment curbs so that chemicals from equipment failure, spillage, or accidental drainage may not enter the water in conduits, treatment, or storage basins. NR 811.39(3)(d)(d) Be located within a containment basin capable of receiving accidental spills, drainage, or overflows without an uncontrolled discharge outside of the containment basin. At minimum, the containment basin shall be sized to contain the volume of the largest tank that could fail. Chemical containment basins shall not be provided with floor drains. Trapped and vented floor drains discharging to sanitary sewers, holding tanks, or the ground surface in accordance with s. NR 811.25 (1) (h) may be installed for chemical rooms outside of containment basins. Chemical feed pumps shall be located within the containment basin. Piping shall be designed to minimize or contain chemical spills in the event of pipe ruptures. NR 811.39(3)(e)(e) Be located above grade, except if this requirement is waived by the department.