Automatic Flushing Cisterns for Urinals (Other than Plastic Cisterns)
1987 Edition

According to IS 2326 (1987), automatic flushing cisterns (excluding plastic variants) must be constructed from materials such as vitreous china conforming to IS 2556 (Part 1) - 1974, cast iron with minimum body and cover thicknesses of 5 mm, and pressed steel with a minimum body thickness of 1.60 mm and cover thickness of 1.25 mm prior to coating. The pressed steel surfaces should have a porcelain enamel or equivalent corrosion-resistant finish. Additionally, all operating parts and lock nuts must be made from corrosion-resistant alloys, including non-ferrous metals or treated steel. The cistern design should prevent mosquito ingress, ensure water-tight and air-tight outlet connections, and feature removable covers secured against displacement. Plastic cisterns are excluded and covered under IS 7231-1984.

IS 2326 specifies nominal cistern volumes of 5 litres and 10 litres with a permissible discharge variation of plus or minus 0.5 litres. For urinal cisterns, a minimum capacity of 2.5 litres per urinal served is stipulated. The flushing mechanism should deliver at least 2.5 litres per urinal at intervals ranging from 10 to 20 minutes. The discharge rate through the flush pipe—a 20 mm internal diameter and 900 mm length smooth pipe—must be a minimum of 5 litres within 7 seconds. The feed outlet must be positioned at least 3 mm above the highest water level prior to siphon activation to prevent backflow.

The standard mandates that automatic flushing cisterns flush at intervals between 10 and 20 minutes. Each flushing cycle must deliver a minimum of 2.5 litres per urinal served. The flushing process should be automatic and regular without requiring manual initiation. The discharge duration is approximately 7 seconds through a specified 20 mm bore, 900 mm length flush pipe, ensuring effective hygiene while optimizing water use.

IS 2326 requires an endurance test in which a randomly selected cistern sample undergoes verification for material conformity, construction integrity, and operational functionality. Subsequently, the cistern must be actuated 3,000 times consecutively without exhibiting any damage or defects. Operational performance includes maintaining a flushing volume of at least 2.5 litres per urinal every 10 to 20 minutes, with consistent flush force and no appreciable drop in discharge rate. Testing must be carried out by accredited laboratories and is mandatory following any design or manufacturing modifications to ensure product reliability and durability.

Plastic flushing cisterns are expressly excluded from IS 2326 as indicated in Clause 1.2. These are governed separately by IS 7231:1984. IS 2326 specifically applies to cisterns made from cast iron, vitreous china, enamelled pressed steel, or other impervious materials agreed upon between purchaser and supplier. Construction requirements include minimum thicknesses, mosquito-proof designs, corrosion resistance, and secure covers, which are outside the scope of plastic cistern specifications.