(a) General. - (i) Chemical application. Chemicals shall be applied by such means as to prevent backflow or back siphonage between multiple points of feed through common manifolds.
- (ii) General equipment design. General equipment design shall be such that:
- (A) Feeders will be able to supply the necessary amounts of chemical throughout the feed range at all times.
- (B) Chemical contact materials and surfaces are resistant to the aggressiveness of the chemical solution.
- (C) Corrosive chemicals are introduced in such a manner as to minimize potential for corrosion.
- (D) Chemicals that are incompatible are not stored or handled together.
- (E) All chemicals are conducted from the feeder to the point of application in separate conduits.
- (F) Chemical feeders and pumps operate at no lower than 20 percent of the feed range.
- (G) Slurry type chemicals, especially lime, are fed by gravity where practical.
(b) Facility design. - (i) Number of feeders. A separate feeder shall be provided for each chemical applied.
- (iii) Dry chemical feeders. Dry chemical feeders shall measure chemicals volumetrically or gravimetrically; they shall be provided with a solution water system and mixer in the solution tank and; shall completely enclose chemicals to prevent emission of dust to the operating room.
- (iv) Positive displacement pumps. Positive displacement pumps shall be sized for the maximum pressure at the point of injection. A backpressure valve shall be provided in instances where chemicals can flow by gravity through the pump and pump check valves.
- (v) Liquid chemical feeders - siphon control. Liquid chemical feeders shall be such that chemical solutions cannot be siphoned into the water supply.
- (vi) Cross-connection control. Cross-connection control must be provided to assure that the service water lines discharging to solution tanks shall be protected from backflow and that liquid chemical solutions cannot be siphoned through solution feeders into the water supply. No direct connection shall exist between any sewer and a drain or overflow from the feeder, solution chamber or tank. All drains shall terminate at least 6 inches (0.15 m) or 2 pipe diameters, whichever is greater, above the overflow rim of a receiving sump, conduit or waste receptacle.
- (vii) In-plant water supply. The in-plant water supply shall be of sufficient quantity and pressure to meet the chemical system needs. A minimum capability of 15 gpm at 50 psi is required.
There shall be a new means of controlling and measuring the water when used for preparing specific solution concentrations by dilution, i.e., rotometer and control valve. The water shall be properly treated for hardness when hardness affects the chemical solution.
- (viii) Storage of chemicals.
- (A) Storage space or tank volume shall be provided for at least 30 days of chemical supply. The storage shall provide protection from intermixing of 2 different chemicals.
- (B) Storage tanks and pipelines for liquid chemicals shall be specific to the chemical and not for alternates.
- (C) Liquid chemical storage tanks must have a liquid level indicator, an overflow and a receiving basin or drain capable of receiving accidental spills or over-flows, and be located in a contained area sized to store the total contents of a ruptured tank.
- (D) All chemical storage tanks shall be constructed of materials which are resistant to the chemical which they store. The tank shall not lose its structural integrity through chemical action or be subject to corrosion.
- (ix) Solution and slurry tanks.
- (A) Feed and dilution systems shall be designed to maintain uniform strength of solution in solution tanks. A mixer shall be provided to mix the tank contents when batching solutions. Continuous agitation shall be provided to maintain slurries in suspension. A means shall be provided to measure the solution level in the tank. Chemical solution tanks shall have a cover. Large tanks with access openings shall have such openings curbed and fitted with overhanging covers.
- (B) Subsurface locations for solution tanks shall be free from sources of possible contamination, and assure positive drainage for groundwaters, accumulated water, chemical spills and overflows.
- (C) Overflow pipes, when provided, shall be turned downward, with the end screened. They shall have a free fall discharge and be located where noticeable.
- (D) Acid storage tanks must be vented to the outside atmosphere, but not through vents shared with any other material.
- (E) Each tank shall be provided with a valved drain, protected against backflow by an air gap of 6 inches (0.15 m) or 2 pipe diameters, whichever is greater.
- (x) Day tanks.
- (A) Day tanks shall be provided where bulk storage of liquid chemical is provided and a dilute solution is to be fed, or where chemicals are manually batched. Day tanks shall meet the requirements of solution tanks. Tanks shall be properly labeled to designate the chemical contained.
- (B) Hand pumps may be used to transfer chemicals from a carboy or drum. A tip rack may be used to permit withdrawal into a bucket from a spigot. Where motor-driven transfer pumps are provided, a liquid level limit switch and an overflow from the day tank shall be provided.
- (C) Continuous agitation shall be provided to maintain chemical slurries in suspension. A mixer shall be provided to mix the initial dilution.
- (xi) Feed lines:
- (A) Shall be of durable material, resistant to the chemical handled.
- (B) Shall be readily accessible for maintenance when located within structures.
- (C) Shall be protected against freezing.
- (D) Shall be readily cleanable by using plugged crosses for 90° bends.
- (E) Shall slope upward from the chemical source to the feeder when conveying gases.
- (F) Shall be designed consistent with scale-forming or solids-depositing properties of the water, chemical, solution, or mixtures conveyed.
- (G) Shall be color coded.
- (H) Shall have a connection for a flushing line.
- (xii) Handling.
- (A) Carts, elevators and other appropriate means shall be provided for lifting chemical containers.
- (B) Provisions shall be made for the transfer of dry chemicals from shipping containers to storage bins or hoppers to minimize the quantity of dust which may enter the room in which the equipment is installed. Provisions shall also be made for disposing of empty bags, drums or barrels which will minimize exposure to dusts. Control may be provided by using:
- (I) Vacuum/pneumatic equipment or closed conveyor systems.
- (II) Facilities for emptying shipping containers in special enclosures.
- (III) Exhaust fans and dust filters which put the hoppers or bins under negative pressure.
- (C) Provision shall be made for measuring quantities of chemicals used to prepare feed solutions.
- (xiii) Housing. Floor surfaces shall be smooth and impervious, slip-resistant and well drained with 2.5 percent minimum slope. Vents from feeders, storage facilities and equipment exhaust shall discharge to the outside atmosphere above grade and remote from air intakes.
(c) Specific chemicals. - (i) Chlorine gas.
- (A) Respiratory protection equipment. Respiratory protection equipment, meeting the requirements of the National Institute of Occupational Safety and Health (NIOSH), shall be available where chlorine gas is handled, and shall be stored at a convenient location, but not inside any room where chlorine is used or stored. The units shall use compressed air, have at least a 30 minute capacity, and be compatible with or exactly the same as units used by the fire department responsible for the plant.
- (B) Chlorine leak detection. Where ton containers are used, or where plants store more than 1000 lbs (454 kg) of chlorine, continuous electronic chlorine leak detection equipment shall be provided.
- (C) Repair kits. Repair kits approved by the Chlorine Institute shall be provided for plants employing chlorine gas chlorination. The chlorine repair kits shall be available for each size container stored at the facility.
- (D) Feed and storage areas. Chlorine gas feed and storage shall be enclosed and separated from other operating areas. The chlorine room shall be provided with a shatter resistant window installed in an interior wall. The room shall be constructed in such a manner that all openings between the chlorine room and the remainder of the plant are sealed. The doors shall be equipped with panic hardware, assuring ready means of exit and opening outward only to the building exterior.
- (E) Ventilation. Where chlorine gas is used, the room shall have an exhaust ventilating system with a capacity which provides one complete air change every two minutes. The ventilating system shall take suction within 18 inches (0.46 m) of the floor, as far as practical from the door and air inlet, with the point of discharge so located as not to contaminate air intakes to any rooms or structures.
Air intakes shall be through louvers near the ceiling. Louvers for chlorine room air intake and exhaust shall facilitate airtight closure.
Separate switches for the fan and lights shall be located outside of the chlorine room and at the inspection window. Outside switches shall be protected from vandalism. A signal light indicating fan operation shall be provided at each entrance when the fan can be controlled from more than one point.
Vents from feeders and storage shall discharge to the outside atmosphere, above grade. The room location shall be on the prevailing downwind side of the building away from entrances, windows, louvers, walkways, etc.
Floor drains shall discharge to the outside of the building and shall not be connected to other internal or external drainage systems.
- (F) Cylinders. Full and empty cylinders of chlorine gas shall be isolated from operating areas, restrained in position to prevent upset, stored in rooms separate from ammonia storage, and stored in areas not in direct sunlight or exposed to excessive heat.
- (G) Heating. Chlorinator rooms shall be heated to 60° F (15.6° C) and be protected from excessive heat. Cylinders and gas lines shall be protected from temperatures above that of the feed equipment.
- (H) Feed lines. Pressurized chlorine feed lines shall not carry chlorine gas beyond the chlorinator room.
- (ii) Acids and caustics.
- (A) Acids and caustics shall be kept in closed corrosion-resistant shipping containers or in covered bulk storage units.
- (B) Acids and caustics shall be pumped in undiluted form from original containers or bulk storage units through suitable pipe or hose to the point of treatment or to a covered day tank.
- (C) An emergency deluge shower and eye wash shall be provided where corrosive chemicals are stored or used.
- (iii) Sodium chlorite. Provisions shall be made for proper storage and handling of sodium chlorite to eliminate any danger of explosion. No hydrocarbons or organics shall be stored with sodium chlorite.
020-12 Wyo. Code R. § 12-11