The 1994 edition of IS 7231 outlines specifications for manually operated plastic flushing cisterns used in toilets and urinals, including high-level, low-level, and coupled models with 5 and 10 litre capacities. This standard details materials, design, functional performance, and testing procedures for both single and dual-flush variants to guarantee longevity, efficiency, and safety. It is a vital reference for manufacturers, engineers, and quality assurance teams engaged in sanitary appliance development and installation.
Overview
The 1994 edition of IS 7231 outlines specifications for manually operated plastic flushing cisterns used in toilets and urinals, including high-level, low-level, and coupled models with 5 and 10 litre capacities. This standard details materials, design, functional performance, and testing procedures for both single and dual-flush variants to guarantee longevity, efficiency, and safety. It is a vital reference for manufacturers, engineers, and quality assurance teams engaged in sanitary appliance development and installation.
Audience
Contents
Structure
This section defines the range and dimensions of plastic flushing cisterns, including the internal diameters and thicknesses of flush pipes for various cistern types. It details recommended materials such as HDPE, polypropylene, and GRP for cistern bodies, and galvanized steel, lead, and copper alloys for pipes. Dual-flush cistern capacities and operational guidelines are also specified.
Lists pertinent IS codes relating to materials and components used in cistern manufacture, such as standards for lead pipes, steel tubes, HDPE and PVC materials, float valves, and plastic components, ensuring harmonized quality and compatibility.
Clarifies terminology related to cistern types and specifies flush pipe diameter and thickness requirements for high-level and low-level cisterns. It also covers installation accessories like pipe clips with rubber buffers and notes on pipe thickness adjustments for corrosive environments.
Details the types of materials approved for each cistern component, including flush pipes, overflow pipes, covers, chains, siphons, valves, and operating mechanisms, along with relevant IS standards for each material to ensure durability and corrosion resistance.
Describes lot conformance criteria, sample sizes for inspection, and acceptance limits for manufacturing batches. It outlines the scope of inspection covering materials, workmanship, surface finish, discharge capacity, and flow rate tests.
Specifies marking requirements including manufacturer identification, discharge capacity, and operating instructions. It provides guidelines for the optional use of the BIS Standard Mark and the dimensions of flush pipes tailored to cistern type.
Describes endurance testing protocols requiring 3,000 flushing cycles without functional degradation. It also includes impact testing procedures and acceptance criteria to verify structural integrity and consistent operational performance.
Outlines additional tests such as distortion resistance, dead load, front thrust, and impact tests. The front thrust test involves applying a horizontal force to simulate real-life stresses while monitoring for operational efficacy.
Provides step-by-step procedures for impact and endurance tests, including sample preparation, test parameters, and evaluation criteria to ensure flushing cisterns meet durability and performance standards.
Defines the approach for selecting samples from production lots, outlines testing requirements, and specifies criteria for lot acceptance or rejection based on conformity with material, construction, and performance standards.
Details supplier obligations for inspection of materials, construction, finish, and functional testing prior to supply. It reiterates critical dimensions and material specifications to ensure consistent quality in delivered products.
Provides guidance on the use and maintenance of flushing cisterns, including component materials, flush pipe specifications, and operation of dual-flush mechanisms to optimize water saving and performance.
Explains mandatory and optional markings on cisterns to provide traceability and user information, including manufacturer details, discharge capacity, instructions, and the conditions for using the BIS Standard Mark under Indian law.
Compiles a comprehensive list of Indian Standards referenced in IS 7231 related to materials, components, and testing procedures relevant to plastic flushing cisterns.
Describes the sampling plans, testing protocols, endurance and impact test details, and criteria for acceptance or rejection of production lots, ensuring consistent product quality and adherence to the standard.
Frequently Asked
IS 7231:1994 prescribes specific materials for the manufacture of plastic flushing cisterns. The cistern body and cover are made from High Density Polyethylene (HDPE), Impact Polypropylene, Acrylonitrile-Butadiene-Styrene (ABS), or Glass Fibre Reinforced Plastic (GRP) as per IS 7328:1992 and related standards. Flush pipes can be constructed from galvanized steel tubes, lead pipes, copper alloy tubes, HDPE pipes, or unplasticized PVC pipes conforming to relevant IS codes such as IS 1239 (Part 1):1990 for steel and IS 404 (Part 1):1977 for lead. Overflow pipes are generally HDPE or unplasticized PVC compliant with IS 4984:1987 and IS 4985:1988. Siphons and valves are fabricated from HDPE, polypropylene, ABS, or GRP. The operating mechanism should use non-ferrous or corrosion-resistant metals, and chains are made from hot-dip galvanized steel or equivalent corrosion-resistant materials. Talc filler in polypropylene is restricted to a maximum of 20%, and minimum thickness requirements are specified to ensure mechanical strength and durability.
IS 7231 categorizes flushing cisterns based on their installation height relative to the toilet pan. A high-level cistern is mounted at least 125 cm above the pan's top edge, utilizing gravity for flushing. Low-level cisterns are installed not more than 30 cm above the pan, positioned closer to the outlet. Coupled cisterns are directly mounted on the back surface of the wash-down water closet, forming an integrated unit. Additionally, overflow pipe requirements specify that the invert or top edge of the overflow pipe must be at least 19 mm above the working water level to prevent siphoning and ensure proper drainage.
According to IS 7231, single-flush cisterns with 5-litre capacity must discharge 5 ± 0.5 litres, while 10-litre cisterns must discharge 10 ± 0.5 litres. Dual-flush cisterns of 10 litres capacity have two discharge volumes: a full flush of 10 ± 0.5 litres and a half flush of 5 ± 0.5 litres. The full flush should discharge water in approximately 6 seconds, while the half flush does not have a specified discharge time. The flush force should remain consistent throughout the discharge period. Coupled cisterns are exempt from discharge rate testing.
IS 7231 specifies several testing procedures to confirm flushing cistern durability and reliable function. The endurance test requires operating a randomly selected cistern 3,000 times with no damage or leakage, particularly checking valve integrity if present. The dead load test applies a 230 N force at a specified point for 30 seconds to assess structural resistance without deformation. Discharge capacity and flush time tests measure water volume expelled and discharge duration against rated values. Impact testing involves dropping a 1 kg steel ball suspended from a 2.5 m wire at a 1 m horizontal distance onto the cistern’s centerline 75 mm above the bottom to check for damage or cracks. All tests are conducted under controlled temperature conditions and repeated periodically or after design changes.
Dual-flush cisterns under IS 7231 employ two distinct controls—such as buttons, levers, or knobs—for full and half flush operations. The full flush releases approximately 10 ± 0.5 litres of water over about 6 seconds, intended for solid waste. The half flush dispenses roughly 5 ± 0.5 litres, typically for liquid waste, with no strict time requirement. The flush mechanism must maintain consistent force during operation to ensure effective flushing. This system supports water conservation by enabling partial flushing when appropriate.
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