diaphragm type (plastic body) float-operated valves for complex water services
1991 Edition

This section defines the applicability of the standard to diaphragm float-operated valves with plastic bodies used in cold water systems up to 45°C, including flush and overhead tanks. It details material requirements per Table 1, performance testing protocols such as the 140 ± 5 seconds discharge test at 0.35 ± 0.01 MPa, and valve selection criteria from Table 2, Column 2. The valves must withstand specified pressures and function reliably under defined conditions. The section also references alignment with BS 1212 (Part 3):1979 and emphasizes polymer usage for sustainability.

Key references include the material specifications in Clause 5.1 and Table 1, valve sampling per Clause 9.2.3.1 and Table 2, and hydraulic pressure testing as described in Clause 8.6 and Annex G. The section also outlines the regulatory framework under the Bureau of Indian Standards Act, 1986, governing the use of the Standard Mark and ensuring compliance with inspection and testing requirements.

This part defines critical terms such as 'float operated valve', describing its operation via diaphragm flexing and discharge arrangements. It specifies test parameters including test pressure (0.35 ± 0.01 MPa) and duration (140 ± 5 seconds), material requirements, valve selection process, and temperature limits. Sampling and testing follow IS 2:1960 for rounding and IS 2500 series for sampling techniques.

Details the mandated materials for valve parts, primarily polyacetal for valve bodies, inlet shanks, seals, and back nuts. Discharge horns may be manufactured from polyacetal, polypropylene, polyethylene, ABS, EVA, or other suitable plastics. Reworked plastic from the manufacturer’s own production is permitted up to 15%. Material selection must ensure mechanical strength, dimensional stability, chemical resistance, and durability under service conditions.

Specifies that components must be free from manufacturing defects such as flash or blockages. The use of reprocessed plastics is restricted to 15% of the manufacturer’s own clean rework. Inspections must verify material conformity, workmanship, and construction integrity, rejecting valves that do not meet these criteria to maintain quality standards.

Covers material usage, hydraulic pressure testing at 1 MPa for 6 ± 1 seconds with the valve held open, and performance testing involving discharge at 0.35 ± 0.01 MPa for 140 ± 5 seconds. The design promotes polymer use to reduce metal content and complies with BIS inspection protocols. References are made to IS 2643 (Part 3) and IS 9762 for detailed dimensional and material specifications.

Specifies material adherence, discharge arrangement requirements including air inlets or backflow prevention devices when discharge points are below the valve centerline. Valve testing involves maintaining a 1 m water head, discharge for 140 seconds, and measuring volume. Automatic cycle tests simulate opening and closing sequences with defined forces and timing to ensure operational reliability.

Describes endurance testing with 200,000 cycles under defined water head and temperature conditions, minimum flow tests with specified water heads and discharge durations, and anti-siphonage tests performed monthly. It details test parameters such as closure force, cycle timing, and water temperature limits to validate valve durability and functionality.

Outlines random sampling methods per IS 4905:1968, sample size determination based on lot size as per Table 2, and acceptance thresholds for defective units. The procedure ensures statistical quality control, with lots accepted if defect counts are within allowable limits and rejected otherwise.

Requires valves to bear permanent, legible markings including manufacturer identification, nominal size, entry type, valve type, and manufacturing date or batch number. The Standard Mark may be applied to indicate BIS certification, ensuring traceability and compliance with the Bureau of Indian Standards Act, 1986.

Specifies minimum inlet shank length of 48 mm and the use of two backnuts with parallel internal threads per IS 2643 (Part 3):1975. The torque test applies 15 Nm with a snug-fit spanner to verify no distortion occurs in threads or hex flats, ensuring mechanical integrity and leak-tight connections.

Details testing for allowable deflection of valve assemblies under a 4.4 N load applied at the float connection. Initial deflection must not exceed 25 mm, with an additional 12 mm allowed after 28 days, totaling a maximum of 37 mm. The test setup involves replacing the diaphragm with a rigid steel disc and mounting in a 19 mm thick wall.

Defines shut-off tests to verify valves remain sealed under specified minimum pressures — 1.05 MPa for high-pressure seats and 0.35 MPa for low-pressure seats. The test rig maintains constant pressure with valves assembled correctly, ensuring no leakage during the test duration.

Describes the setup where valves fitted with low-pressure seats discharge water from a cistern at a 1.00 ± 0.01 m head through a 15 mm pipe and gate valve into a container for 140 seconds. The test confirms valve operation under low pressure and minimal flow conditions.

Specifies testing discharge arrangements under dynamic pressure of 1 MPa for 6 ± 1 seconds with the valve fully open. The test ensures no permanent deformation or component separation occurs, validating the robustness of discharge components under hydraulic stress.