copper alloy fancy single taps, combination tap assembly and stop valves for water services

IS 8931: Scope - Key Specifications & References

Scope Summary:

• Covers materials and components related to water supply fittings.
• Emphasizes compliance with material specifications and testing before use (Clause 9.1).
• Material certification by suppliers or testing per relevant IS standards is mandatory.

Key Material Specifications (Table 1 references):

Material Testing (Clause 9.1):

• Tests as per corresponding IS specifications.
• Supplier certification or independent testing to ensure compliance.
• Sampling and conformity criteria detailed in Annex E.

Dimensional Specifications:

• Dimensions must comply with IS 2643 (pipe threads).
• Example: Pressure Take Off Tee dimensions (Table 10) specify nominal sizes, thread sizes, and bolt details.

Recommended Procedure for Flow Rate Accuracy (Clause 4.2.8):

1. Measure flow rate at various pressures (0.1 to 0.5 MPa).
2. Plot flow rate (Q) vs. pressure (P) on logarithmic scale.
3. Determine flow rate at 0.3 MPa from the curve.

Summary Diagram: Material Compliance Flow

flowchart TD
    A[Material Procurement] --> B{Supplier Certification?}
    B -- Yes --> C[Use Material]
    B -- No --> D[Conduct Material Tests per IS Specs]
    D --> E{Pass Tests?}
    E -- Yes --> C
    E -- No --> F[Reject Material]

In brief: IS 8931 mandates strict material compliance verified by tests or certifications referencing multiple IS standards, with detailed dimensional and procedural guidelines to ensure quality in water supply fittings.

IS 8931 - Definitions: Key Points & References

Clause 9.1: Material Test

• Materials must comply with specifications in Table 1.
• Tests or supplier certification required before use.

Clause 2.1: Referenced Indian Standards (Examples)

Clause 6.1: Figures are illustrative; dimensions must be complied with.

Clause 4.2.8: Flow Rate Measurement Procedure

• Measure flow rate (Q) at pressures (P) from 0.1 to 0.5 MPa.
• Plot Q vs. P on logarithmic scale.
• Determine Q at 0.3 MPa.

Table 10: Dimensions of Pressure Take Off Tee (in mm)

Thread sizes conform to IS 2643 (Part 3): 1975.

Summary

• Definitions rely on referenced IS standards for materials and dimensions.
• Material compliance is verified by tests or certification.
• Dimensional and procedural specifications are given for fittings and testing.
• Refer to IS 2643 for pipe thread dimensions.

flowchart TD
    A[Material Selection] --> B{Certified or Tested?}
    B -- Yes --> C[Use Material]
    B -- No --> D[Conduct Tests per Table 1]
    D --> C
    C --> E[Fabrication per Dimensions]
    E --> F[Compliance Check]

For detailed definitions, refer to the respective IS standards listed in Clause 2.1.

IS 8931: Nominal Sizes Key Specifications & Tables

1. Nominal Size Identification (Clause 11.1.1)

• Nominal size of taps and valves must be marked on carton/packing for easy identification.

2. Dimensions for Stop Valve and Angle Stop Valve Bodies (Clause 7.2.5)

Conforms to IS 2643 (Part 3): 1975 / IS 554: 1985

3. Bonnet Assembly Dimensions (Clause 7.3.2, Fig. 8, Table 9)

IS 8931: Materials Key Specifications & Tables

1. Material Tests (Clause 9.1)

• Materials must be certified by suppliers or tested as per relevant IS standards before use.

2. Mechanical Strength (Clause 9.2.4)

• Mechanical properties must comply with corresponding material IS specifications.

3. Material Table for Components (Clause 5.1, Table 1)

4

IS 8931: Manufacture, Workmanship and Construction - Key Points

1. Material Tests (Clause 9.1)

• Materials must comply with specifications in Table 1.
• Suppliers must certify compliance or tests must be conducted before use.

2. Material Specifications (Clause 5.1 & Table 1)

• Materials for taps and valves follow IS standards such as:
  • IS 292: Leaded brass ingots and castings
  • IS 318: Leaded tin bronze ingots and castings
  • IS 319: Free cutting leaded brass bars, rods, sections
  • IS 407: Brass tubes
  • IS 410: Cold rolled brass sheets, strip, foil
  • IS 781: Cast copper alloy taps and valves

3. Workmanship & Construction (Clause 6)

• Dimensions must strictly follow the standard.
• Figures are illustrative; actual construction must meet specified dimensions.
• Refer to related IS codes for threads, coatings, rubber compounds, etc. (Annex A).

4. Important IS Codes for Reference (Annex A)

Summary Table: Material Standards for Components

Visual Concept: Material Flow & Compliance

flowchart TD
    A[Raw Material Procurement] --> B{Supplier Certification?}
    B -- Yes --> C[Use Material]
    B -- No -->

IS 8931: Components and Dimensions Key Data

1. Body to Bonnet Connection & Seat

• Refer Clause 7.2.1 and Table 2 with Fig. 1 for detailed dimensions (not provided here).

2. Bonnet Assembly Dimensions (Clause 7.3.2, Table 9, Fig. 8)

(All dimensions in mm)

• Washer plate per IS 2643 (Part 3): 1975.
• Figures are illustrative; dimensions must be strictly followed (Clause 6.1).

Summary Diagram (Bonnet Assembly Components)

graph LR
A

IS 8931: Surface Finish and Plating Key Points

• Significant Surfaces (Clause 8.1.1):
  Surfaces essential for serviceability or appearance, covered by coating. Internal hollow parts (e.g., inside knobs, caps) are not significant.

• Surface Finish Requirements:

  • Taps, Combination Tap Assemblies, Stop Valves (Clause 8.1):
    Must be nickel-chromium plated on significant surfaces.
    Exception: Bodies of concealed/side stop valves on pillar mounting may be polished bright or left as cast finish.
  • Plastic Knobs and Components (Clause 8.3):
    May be used as as-moulded finish or nickel-chromium plated per Service Grade No. 2 of IS 8376:1988.
  • Zinc Base Alloy Knobs and Components (Clause 8.4):
    Must be nickel-chromium plated per Service Grade No. 2 of IS 4828:1983.

Nickel-Chromium Plating: Service Grade No. 2 (Summary)

Concept Diagram: Surface Finish Application

graph LR
A[Tap Assembly] --> B[Significant Surfaces]
B --> C[Nickel-Chromium Plating]
A --> D[Non-Significant Surfaces]
D --> E[No plating or Cast finish]
F[Plastic Knobs] --> G[As-moulded finish or Nickel-Chromium Plated]
H[Zinc Alloy Knobs] --> I[Nickel-Chromium Plated]

Summary:
Use nickel-chromium plating on all significant surfaces of taps and valves per IS 837

IS 8931: Performance Requirements and Tests Summary

1. Material Tests (Clause 9.1)

• Conduct tests as per corresponding material specs (see Table 1).
• Materials must be certified or tested to confirm compliance before use.

2. Performance Test (Clause 9.2)

• Follow test equipment, procedure, and duration as per Annex C.
• Multiple flow rate measurements at pressures between 0.1 MPa and 0.5 MPa.
• Plot flow rate (Q) vs. pressure (P) on logarithmic scale.
• Determine flow rate at 0.3 MPa from the curve for accuracy.

3. Calibration (Clause 4.2.8 & D-5)

• Regular calibration of measuring devices and test circuits is recommended.

4. Dimensions of Pressure Take Off Tee (Table 10)

All dimensions in mm, threads per IS 2643 (Part 3):1975.

Key Formula for Flow Rate Curve Plotting

[ \log Q = f(\log P) ]

• Plot several (P, Q) points.
• Interpolate Q at P = 0.3 MPa.

flowchart LR
    A[Start Test] --> B[Measure Flow Rate Q at Various Pressures P]
    B --> C[Plot log(Q) vs log(P)]
    C --> D[Interpolate Q at P=0.3 MPa]
    D --> E[Verify Performance]
    E --> F[Calibrate Equipment Regularly]

This ensures accurate performance validation per IS 8931.

IS 8931: Sampling and Criteria for Conformity (Annex E)

E-1 Scale of Sampling

• Items must be randomly selected from the lot.
• Follow IS 4905:1968 for random selection procedures.

E-2 Number of Tests and Criteria for Conformity

• Acceptance Criteria:
  The lot is accepted if the number of defective items ≤ acceptance number (Column 3).

Additional Notes:

• Sampling ensures quality control by testing a representative subset.
• Sub-sample size is used for detailed testing if required.
• This method balances inspection cost and confidence in quality.

flowchart TD
    A[Lot of Taps & Valves] --> B[Random Sampling per IS 4905]
    B --> C[Sample Size per Table 11]
    C --> D{Defective Items ≤ Acceptance Number?}
    D -->|Yes| E[Lot Accepted]
    D -->|No| F[Lot Rejected]

This concise framework ensures statistically valid quality evaluation per IS 8931.

IS 8931 - Watertightness Characteristics (Annex B, Clause 9.2.1.4)

Key Specifications:

• Scope: Tests verify watertightness of complete taps and valves (not production QC).
• Test Types:
  • Watertightness (9.2.1)
  • Pressure Resistance (9.2.2)
• Test Equipment: As per Clause B-2, specialized laboratory setups simulate operating conditions.
• Test Duration: Minimum durations specified in Clause 2.4 (B-2.4) to ensure reliability.
• Watertightness Checks:
  • Bonnet assembly sealing on seat.
  • Upstream valve sealing integrity.

Typical Test Procedure Summary:

Formula for Leakage Rate (if applicable):

[ Q = \frac{V}{t} ]

• Q: Leakage rate (volume/time)
• V: Volume of leaked water
• t: Test duration

flowchart LR
    A[Test Setup] --> B[Apply Test Pressure]
    B --> C[Maintain for Test Duration]
    C --> D[Check Leakage at Bonnet & Upstream]
    D --> E{Leakage within Limits?}
    E -->|Yes| F[Pass]
    E -->|No| G[Fail]

Summary: IS 8931 Annex B mandates rigorous lab testing of taps/valves for watertightness, focusing on bonnet sealing and upstream integrity, under specified pressures and durations, ensuring reliable performance.

IS 8931: Pressure Resistance Characteristics (Clause 9.2.2)

• Pressure Resistance defines the maximum internal pressure a component (like pressure take-off tees) can safely withstand without failure.
• For pressure take-off tees (Clause 3.2), made of brass, dimensions are per Table 10 (refer to IS 8931 Table 10 for exact sizes).

Key Specifications:

• Material: Brass (for pressure take-off tees)
• Dimensioning: As per Table 10 (includes diameter, thickness, and length)
• Test Pressure: Typically, components are tested at 1.5 times the maximum working pressure (Clause 9.2.4 Mechanical Strength)

Typical Formula for Pressure Resistance:

[ P = \frac{2 \times t \times \sigma}{d} ]

Where:

• (P) = Allowable internal pressure
• (t) = Wall thickness
• (\sigma) = Allowable stress of material
• (d) = Internal diameter

Hydraulic Characteristics (Clause 9.2.3):

• Flow rate tests ensure the tee or device does not cause pressure drops beyond limits.
• Flow rate (Q) relates to pressure drop (\Delta P) by: [ Q = C_d A \sqrt{\frac{2 \Delta P}{\rho}} ] Where:
• (C_d) = Discharge coefficient
• (A) = Cross-sectional area
• (\rho) = Fluid density

Summary Table (Example from IS 8931 Table 10):

flowchart LR
    A[Pressure Take-off Tee] --> B[Material: Brass]
    B --> C[Dimensions per Table 10]
    C --> D[Pressure Resistance Calculation]
    D --> E[Hydraulic Flow Rate Test]

Refer IS 8931 Table 10 and Clauses 9.2.2 - 9.2.4 for detailed values and test procedures.

IS 8931: Hydraulic Characteristics (Clause 9.2.3 & Annex D)

Key Points:

• Objective: Measure flow rate of taps/valves with accessories at a given pressure.
• Test Setup (Annex D, Clause 9.2.3.3):
  • Apparatus:
    • Supply circuit (provides controlled water pressure)
    • Test circuit (measures flow through the tap/valve)
  • Refer to Fig. 9 for apparatus layout.

Flow Rate Measurement Formula:

[ Q = C_d \times A \times \sqrt{2gH} ]

Where:

• (Q) = Flow rate (m³/s)
• (C_d) = Discharge coefficient (dimensionless)
• (A) = Cross-sectional area of outlet (m²)
• (g) = Acceleration due to gravity (9.81 m/s²)
• (H) = Pressure head (m)

Typical Test Parameters:

Summary:

• Measure flow rate at a specified pressure using the test apparatus.
• Use flow rate formula to verify performance.
• Ensure test complies with Annex D setup for repeatability.

flowchart LR
    A[Water Supply] --> B[Supply Circuit]
    B --> C[Test Circuit]
    C --> D[Tap/Valve Under Test]
    D --> E[Flow Measurement Device]

This setup ensures accurate hydraulic characterization per IS 8931 standards.

IS 8931: Sampling and Criteria for Conformity

Sampling Procedure (Annex E, Clause E-1)

• Items are randomly selected from the lot.
• Follow IS 4905:1968 for randomness procedures.

Number of Tests & Acceptance Criteria (Clause E-2, Table 11)

• Acceptance Rule: Lot is accepted if defective items ≤ acceptance number.

Additional Notes:

• Sub-sample sizes are used for detailed testing.
• Calibration of measuring devices is recommended regularly (Clause D-5).
• Flow rate measurement at multiple pressures (0.1 to 0.5 MPa) with interpolation at 0.3 MPa is suggested for accuracy.

This ensures statistically valid quality control of taps and valves per IS 8931.

Committee Composition per IS 8931

The Sanitary Appliances and Water Fittings Sectional Committee, CED 3 and Domestic and Municipal Water Fittings Subcommittee, CED 3:2 are composed of representatives from:

• Government bodies (e.g., Delhi Water Supply, Central Public Health Engineering)
• Research institutes (e.g., CSIR, National Environmental Engineering Research Institute)
• Industry representatives (e.g., Kirloskar Brothers, Hindustan Sanitaryware)
• Municipal corporations and water authorities
• Testing and quality control organizations
• BIS ex-officio members

Key Specifications on Committee Composition:

• Chairman & Convener lead the committees.
• Members include technical experts, industry leaders, government engineers, and research officers.
• Alternates are appointed for most members to ensure continuity.
• The committee ensures standards development and conformity testing.

Sampling & Conformity (Table 11 from Clause 1.3)

This ensures rigorous quality control through statistically valid sampling.

flowchart TD
    A[Lot Size] --> B[Select Sample Size]
    B --> C{Acceptance Number}
    C -->|<= Acceptance| D[Lot Accepted]
    C -->|> Acceptance| E[Lot Rejected]

For detailed design dimensions, refer to Clause 7.2.1 and Table 2 in IS 8931.