polyethene floats (spherical) for float valves

IS 9762: Scope - Key Specifications & Tables

Scope Overview

IS 9762 covers dimensions, material specifications, and testing criteria for floats (used in water level indicators).

Key Table: Dimensions of Floats (Clause 7.2)

Note: Threading tolerances per IS 4218 (coarse series).

Sampling & Acceptance Criteria (Clause 9.4.2)

• All sampled floats must pass leakage, water absorption, deflection, impact, and

IS 9762 Key References: Float Dimensions, Wall Thickness & Testing

1. Float Dimensions & Wall Thickness (Clause 7.2, Table 1)

Note: Thread tolerances per IS 4218 (coarse series).

2. Sampling & Acceptance for Tests (Clause 9.4.2, Table 3)

3. Wall Thickness Minimum (Clause 6.2.1)

• Wall thickness of float C must meet or exceed values in Table 1

IS 9762: Key Definitions & Specifications

Clause 3.0 - Definitions

• Definitions in 3.1 and 3.2 apply to terms used in the standard (refer to the code for exact wording).

Clause 7.2 - Dimensions of Float, Boss, and Insert (Polyethylene Material)

Note: Thread tolerances follow IS 4218 coarse series.

Clause 9.4.2 - Sampling & Acceptance for Tests

| Number of Floats in Lot | Sample Size | Acceptance Number (Defectives Allowed) | |

IS 9762: Designation & Key Specifications for Floats

Designation (Clause 3.0, 3.2)

• Floats are designated as HP (High Pressure) or LP (Low Pressure) followed by nominal size (mm).
  • Example:
    • HP 25 = High Pressure float, nominal size 25 mm
    • LP 40 = Low Pressure float, nominal size 40 mm

Material

• HDPE conforming to PEBW A50 T 090 or PEBN A50 T 090 per IS 7328:1992.
• Up to 10% rework material from the same manufacturer allowed.

Key Dimensions (Table 1, Clause 7.2)

IS 9762: Key Specifications for Materials (Clause 6.2, 7.2, 9.4.2)

1. Wall Thickness (Clause 6.2, 6.2.1)

• Minimum wall thickness C of polyethylene floats varies by nominal size (mm):

2. Dimensions of Floats (Clause 7.2, Table 1)

Note: Threading tolerances follow IS 4218 (coarse series).

3. Sampling & Acceptance (Clause 9.4.2, Table 3)

| Lot Size (Floats) |

IS 9762: Dimensions and Tolerances for Floats

Key Dimensions (in mm) — Table for Polyethylene Floats (Clause 7.2)

Tolerances (Clause 6.1.1)

• Diameter variation of floats: ±2.5 mm

Notes:

• Threading tolerance as per IS 4218 (coarse series).
• Wall thickness minimum values ensure structural integrity (Clause 6.2).

Summary Diagram of Float Dimensions

graph LR
A[Float Diameter (HP)] --> B[Wall Thickness (C)]
B --> C[Insert Wall Thickness (t)]
C --> D[Insert Base Thickness (T)]
D --> E[Axial Length of Thread (B)]
E --> F[Tapping of Boss (A)]

This ensures compliance with dimensional and tolerance requirements for polyethylene floats under IS 9762.

IS 9762: Manufacture and Workmanship - Key Formulas, Tables & Specs

1. Dimensional Specifications (Clause 7.2 & Table 1)

Note: Thread tolerances as per IS 4218 (Coarse series).

2. Sampling and Acceptance Criteria for Manufacture & Workmanship (Clause 9.3.1, Table 2)

IS 9762: Performance Requirements & Tests Summary

Key Tests (Clause 9.4.2)

Each float must pass tests under Clauses 8.1 (Leakage), 8.2 (Water Absorption), 8.3 (Deflection), and 8.4 (Impact & Boss Tests). Failure in any test means the float is defective.

Sampling & Acceptance Criteria (Table 3)

• No defective floats are allowed in the sample for the lot to conform.

Deflection Test Setup

• Refer to Fig. 1 in IS 9762 for the counterbalancing float deflection test arrangement.

Important Notes:

• Specimens must meet Clause 8.2 water absorption limits.
• The lot is accepted only if defective floats ≤ acceptance number.
• Tests ensure durability and performance under service conditions.

flowchart LR
    A[Select Sample] --> B[Test for Leakage (8.1)]
    B --> C[Test for Water Absorption (8.2)]
    C --> D[Test for Deflection (8.3)]
    D --> E[Test for Impact & Boss (8.4)]
    E --> F{Any Defective?}
    F -- Yes --> G[Reject Float]
    F -- No --> H[Float Passes]
    H --> I{Defectives in Sample ≤ Acceptance Number?}
    I -- Yes --> J[Lot Accepted]
    I -- No --> K[Lot Rejected]

This ensures quality control per IS 9762 for float performance.

IS 9762: Sampling and Criteria for Conformity

Key Points from Clauses 9.1, 9.3.1, and 9.4.1:

• Sampling size depends on the lot size.
• Acceptance criteria are based on the number of defectives found in the sample.
• Different tests have different sample sizes (see Table 3 for test-wise samples).

Table 2: Sampling for Dimensional, Manufacture, and Workmanship Tests

Conformity Criterion:

• A lot conforms if the number of defectives ≤ acceptance number (c) for the sample size.

Summary:

• Sample size (n) and acceptance number (c) increase with lot size.
• Zero defect acceptance for small lots; allowance increases for larger lots.
• Use Table 3 for test-specific sampling sizes.

flowchart TD
    A[Lot Size] --> B{Check Table 2}
    B -->|Sample Size (n), Acceptance (c)| C[Take Sample]
    C --> D{Count Defectives}
    D -->|Defectives ≤ c| E[Lot Accepted]
    D -->|Defectives > c| F[Lot Rejected]

This ensures quality control through statistically valid sampling per IS 9762.

IS 9762: Marking and Certification Key Points

Marking Requirements (Clause 10.1)

Each float must be legibly marked with:

• Manufacturer's name or trade-mark
• Float designation
• Batch/lot number

BIS Certification Mark (Clause 10.2)

• Floats may bear the BIS Standard Mark.
• Use of this mark is regulated by the Bureau of Indian Standards Act, 1986.
• Licensing conditions for the Standard Mark are available from BIS.

Sampling & Acceptance Criteria for Tests (Clause 9.4.2 & Table 3)

• Tests include Leakage & Water Absorption, Deflection, Impact, and Boss Tests.
• If any float fails, it is defective.
• Lot conforms if defectives ≤ acceptance number (which is 0 in all cases).

This ensures quality control and traceability of floats per IS 9762.

IS 9762: Test for Leakage and Water Absorption (Clause 8.1 & Annex A)

Test Procedure (Annex A):

• Weigh the float before immersion: M1
• Immerse in water at 55 ± 2°C, water level at least 50 mm above float top
• Duration: 100 hours
• Remove, dry surface, weigh again: M2

Key Formula:

[ \text{Water Absorption (%)} = \frac{M_2 - M_1}{M_1} \times 100 ]

Acceptance Criteria:

• Water absorption ≤ 0.5%
• No visible leakage during immersion

Summary Table:

flowchart TD
    A[Weigh float (M1)] --> B[Immerse in water (55±2°C)]
    B --> C[Maintain water level ≥ 50mm]
    C --> D[Immersion for 100 hours]
    D --> E[Remove & dry float]
    E --> F[Weigh float (M2)]
    F --> G[Calculate Water Absorption %]
    G --> H{Is absorption ≤ 0.5% and no leakage?}
    H -- Yes --> I[Pass]
    H -- No --> J[Fail]

This test ensures float integrity and durability by limiting water ingress and leakage.

IS 9762 – Deflection Test (Clause 8.2, Annex B)

• Test Objective: Measure deflection of the float under specified loading.
• Acceptance Criteria: Maximum deflection ≤ 7 mm.
• Test Setup:
  • Follow arrangement as per Fig. 1 (Deflection Test Arrangements) in Annex B.
  • Use counter balancing float to apply load.
• Procedure Summary:
  • Apply load gradually on the specimen.
  • Measure vertical deflection at the midpoint or specified location.
• Reference Clause:
  • Clause 3.1 (B-3.1) states specimen must satisfy Clause 8.2 requirements.
  • Clause 9.4 includes deflection as one of the quality tests.

Key Points Summary

flowchart LR
    A[Apply Load] --> B[Measure Deflection]
    B --> C{Deflection ≤ 7 mm?}
    C -- Yes --> D[Pass Test]
    C -- No --> E[Fail Test]

This ensures structural integrity and performance compliance of the float under load.

IS 9762: Resistance of the Boss to Distortion

Key Points from Clause 8.4 & Annex C:

• The boss and/or float must withstand distortion tests as per Annex C.
• Test method involves applying specified loads to check for visible distortion or damage.
• Bosses must be integral with the float and fitted with copper alloy corrosion-resistant inserts (Clause 7.2).

Specifications for Boss Inserts (Table 1 excerpt):

(Refer to IS 9762 Table 1 for full details)

Resistance to Distortion - Conceptual Formula:

While IS 9762 does not provide explicit formulas, resistance depends on:

[ \sigma = \frac{F}{A} ]

• σ = stress on boss material
• F = applied load during distortion test (from Annex C)
• A = cross-sectional area of boss

The boss must resist this stress without permanent deformation.

flowchart LR
    A[Applied Load on Boss] --> B[Stress on Boss Material]
    B --> C{Stress ≤ Allowable Stress?}
    C -- Yes --> D[No Distortion/Damage]
    C -- No --> E[Boss Distorted/Damaged]

Summary:

• Use Annex C test method for distortion.
• Boss must remain undistorted under test load.
• Use copper alloy inserts as per Table 1.
• Design boss cross-section to keep stress below material yield.

Committee Composition - IS 9762

The Sanitary Appliances and Water Fittings Sectional Committee (CED 3) oversees IS 9762. Key points:

• Chairman: Shri S. Prakash (Delhi Water Supply and Sewage Disposal Undertaking)

• Members: Experts from diverse organizations including:

  • Central Public Health and Environmental Engineering
  • National Environmental Engineering Research Institute (CSIR)
  • Maharashtra Water Supply and Sewage Board
  • Central Glass and Ceramic Research Institute (CSIR)
  • Municipal Corporations, Indian Water Works Association, BIS, and various industries

• Member-Secretary: Shri S. S. Sethi (Director, Civil Engineering, BIS)

Sampling and Acceptance Criteria (Clause 9.3.1 & Table 2)

• A lot is conforming if defectives ≤ acceptance number.

This committee structure ensures expert representation for standards development, while the sampling plan maintains quality control.