The standard offers comprehensive guidance on the storage, handling, preparation, and dosing of coagulants like alum and iron salts in water treatment facilities. It is crucial for professionals managing water purification processes to design and maintain safe, corrosion-resistant chemical dosing setups, including solution tanks, mixers, and feed equipment adapted to different plant requirements.
Overview
The standard offers comprehensive guidance on the storage, handling, preparation, and dosing of coagulants like alum and iron salts in water treatment facilities. It is crucial for professionals managing water purification processes to design and maintain safe, corrosion-resistant chemical dosing setups, including solution tanks, mixers, and feed equipment adapted to different plant requirements.
Audience
Contents
Structure
This section defines the extent of the standard, detailing requirements for chemical solution dosing devices such as chlorinators and bleaching powder feeders. It includes rounding conventions for calculated values aligned with IS 2:1960 and specifies solution concentration guidelines as per the standard's tables. Additionally, it lists crucial referenced Indian Standards related to materials, electrical installations, and safety.
Highlights Indian Standards cited within the document that ensure compliance for materials, equipment, and safety in water treatment chemical handling. Examples include standards for grey iron castings, aluminium sulphate specifications, induction motors, electrical wiring, and weighing machines. It also covers rounding rules per IS 2:1960.
Details handling guidelines for various coagulants, their chemical formulas, forms, solubility, storage container materials, feeding methods, solution strengths, and compatible handling materials to prevent corrosion and ensure safety.
Sets forth specifications for coagulant storage, including damp-proof storage rooms, flood prevention measures, minimum storage volumes near feed points, and material considerations for containers based on chemical characteristics.
Emphasizes the importance of accurate weighing of coagulants upon receipt and prior to dosing, with reference to specific Indian Standards for weighing equipment. Also describes preparation and feeding practices to ensure safety and precision.
Specifies the recommended number and capacity of solution tanks, tank shapes, mixing arrangements, and material selection for corrosion resistance. Also includes guidelines for chemical preparation and storage for various coagulants.
Describes mechanical and compressed air agitation methods, including turnover times, motor and paddle materials, air supply specifications, and piping materials to achieve uniform and complete solution mixing.
Outlines material requirements and minimum diameter specifications for gravity and pressure feed lines as well as drain lines. Discusses proper layout to avoid air pockets, provisions for cleaning, freezing protection, and maintenance routines.
Details equipment used to regulate chemical dosing, including flow measurement methods like rotameters, orifices, and calibrated weirs. Specifies suitable materials, installation of strainers for preventing blockages, and recommended feeding mechanisms such as positive displacement pumps.
Covers safety precautions for handling corrosive and hygroscopic chemicals, including storage conditions, use of personal protective equipment, electrical installation safety as per relevant IS codes, and routine maintenance of dosing and mixing equipment.
Frequently Asked
Coagulants should be stored in a moisture-resistant, water-tight space protected from flooding. A minimum storage volume equivalent to three months' average usage is advised, with at least one week's supply kept near the dosing equipment for operational convenience. Bagged materials should be stacked off the floor to avoid moisture damage.
Solution tanks may be constructed from wood or reinforced cement concrete coated with bituminous paint, and lined with PVC or epoxy for corrosion resistance. Mild steel tanks require linings of rubber, PVC, or epoxy. Feed and drainage pipelines should be made from durable, corrosion-resistant materials such as PVC, rubber-lined steel, or acid-resistant alloys, with minimum diameters of 50 mm for gravity feed and 25 mm for pressure feed lines.
Coagulants must be weighed accurately before preparation. Filtered or settled clear water is used to prepare solutions. Mixing is achieved either mechanically, with an agitator designed to provide a two-hour turnover in alum tanks, or by compressed air agitation supplying 0.1 to 0.15 cubic meters of air per cubic meter of solution. All components in contact with chemicals should be corrosion-resistant to ensure complete dissolution and uniformity.
Recommended dosing devices include solution feed equipment fitted with flow measurement instruments such as rotameters, calibrated orifices, or weirs. These devices should be constructed from non-corrodible materials. Strainers are essential before dosing equipment to remove impurities and prevent clogging, and feeding is commonly achieved using positive displacement pumps or constant head devices.
Electrical wiring and fixtures must comply with IS 732 and IS 5216 standards to ensure safety. Motors should be totally enclosed fan-cooled (TEFC), with cooling methods and protection levels conforming to IS 6362 and IS 4691. Wiring must be installed to prevent moisture ingress and chemical exposure, and materials used for pumps and motors should be corrosion-resistant, ensuring safe and durable operation in chemical environments.
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