Method for performance testing of water meters (domestic type)

IS 6784: Scope - Key Formulas, Tables & Specifications

1. Rounding Off Values

• Final test values must be rounded per IS 2:1960 rules.
• Retain the same significant figures as specified in the standard.

2. Test Equipment (Clause 3.1)

• Pump set (centrifugal or overhead tank)
• Mercury manometer / pressure gauges / differential pressure gauge
• Measuring tanks with level indicator
• Sluice or gate valves
• Stopwatch or electronic timer

3. Measuring Device Capacity (Clause 3.2.3, Table)

• Least count of measuring tank in the last 10% water collection must follow IS 779:1994 Table 1.

4. Temperature Suitability & Life Test (Clause 9.3)

• After life test, dismantle the meter to check wear on:
  • Vane wheel/piston
  • Impeller shaft & measuring chamber
  • Bearings, gears, pinions, pivots, gland packing

5. Test Report Format (Annex A)

Includes:

• Meter type, class, size
• Max flow rating, min discharge with pressure loss limits
• Pressure loss & metering accuracy errors
• Transitional & starting flow ratings

flowchart LR
  A[Test Equipment] --> B[Pump Set]
  A --> C[Pressure Gauges]
  A --> D[Measuring Tank]
  A --> E[Valves]
  A --> F[Timer]
  
  G[Measuring Tank Capacity] --> H

IS 6784 Key References, Tables & Specifications

Rounding Off (Clause None)

• Final test values must be rounded per IS 2:1960.
• Retain the same significant figures as specified in the standard.

Temperature Suitability Test (Clause 9.3)

• After life test, dismantle the meter showing greatest deterioration.
• Check wear of:
  • Vane wheel/piston
  • Impeller shaft & measuring chamber
  • Bearings, gears, pinions, pivots, gland packing
• Test report format: See Annex A.

Test Report Format (Annex A)

Measuring Device Requirements (Clause 3.2.3, Table)

• Least count of measuring tank in final 10% must conform to IS 779:1994 Table 1.

Test Setup

• Refer to Fig. 1 in IS 6784 for test setup schematic.

flowchart LR
    A[Water Meter] --> B[Life Test]
    B --> C{Deterioration?}
    C -- Yes --> D[Dismantle & Inspect]
    D --> E[Check Wear &

IS 6784 - Test Equipment & Set-up for Pressure Tightness, Metering Accuracy, and Loss of Pressure

1. Test Equipment (Clause 3.1)

• Pump set: Centrifugal pump and/or overhead tank.
• Pressure measurement: Mercury manometer, pressure gauges, and/or differential pressure gauge.
• Measuring tanks: With level indicators.
• Valves: Sluice or gate valves.
• Timing device: Stopwatch or electronic timer.

2. Alternative Equipment for Pressure Tightness Test (Clause 3.3)

• Hand pumps
• Reciprocating pumps
• Pressure intensifier
• Dead weight pressure gauge tester

3. Temperature Suitability Test Equipment (Clause 4)

• Container with heating elements
• Temperature control device maintaining 45°C ± 1°C

4. Life Test Equipment (Clause 5)

• Centrifugal pump with regulating valves delivering flow Qn through two meters in series
• Horizontal test bench
• Pressure gauge of suitable range

5. Key Parameters for Test Report (Annex A)

Typical Test Setup Diagram

flowchart LR
    A[Water Source] --> B[Pump Set / Overhead Tank]
    B --> C[Pressure Gauge / Manometer]
    C --> D[Valves (Sluice/Gate)]
    D --> E[Water Meter Under Test]
    E --> F[Measuring Tank with Level Indicator]
    F --> G[Stopwatch / Timer]

This setup ensures accurate measurement of pressure tightness, metering accuracy, and pressure loss under controlled flow and temperature conditions per IS 6784.

IS 6784: Test Equipment & Specifications for Temperature Suitability Test

Key Specifications (Clause 4 & 8.2)

• Test Container:
  • Container with heating elements
  • Temperature control device to maintain 45°C ± 1°C
• Test Duration:
  • Meter immersed for 10 hours
• Condition:
  • Dust cap or water entry prevention device removed during immersion
• Meter Placement:
  • Meter tested individually or in series (Clause 7.2)
  • Meter must have qualified per IS 779:1994 before temperature test

Test Equipment Summary

Additional Notes

• After temperature test, meters undergo life test and wear examination (Clause 9.3).
• Focus on wear of vane wheel/piston, impeller shaft, bearings, gears, pivots, and gland packing.

Temperature Suitability Test Procedure (Simplified)

flowchart TD
    A[Select Meter (IS 779 qualified)] --> B[Remove dust cap/water seal]
    B --> C[Immerse meter in water container]
    C --> D[Maintain temperature at 45°C ± 1°C]
    D --> E[Keep immersed for 10 hours]
    E --> F[Remove and inspect meter]

For detailed test reports, refer to Annex A of IS 6784.

IS 6784: Test Equipment & Life Test Specifications

1. Test Equipment for Life Test (Clause 5)

• Pump: Centrifugal pump with regulating valves delivering flow at Qn through two water meters in series.
• Test Bench: Suitable horizontal test bench.
• Pressure Gauge: Appropriate range pressure gauge.

2. Life Test Requirements (Table 1, Clause 9.1)

• Qn = Nominal flow rate in kl/h.

3. Additional Notes

• Meters may be tested individually or in series.
• Life test conducted every 6 months on two unopened meters per size/class.
• Temperature suitability test at 45°C ± 1°C (Clause 4).
• After temperature test, meters must pass flow and pressure tightness tests (Clause 8.2.1).

4. Summary Diagram

flowchart LR
    A[Centrifugal Pump] --> B[Regulating Valves]
    B --> C[Two Water Meters in Series]
    C --> D[Pressure Gauge]
    D --> E[Horizontal Test Bench]
    E --> F[Flow Measurement & Timing]

This setup ensures accelerated endurance testing per IS 6784 for reliable meter performance.

IS 6784: Metering Accuracy Test Key Points

• Test Flow Rates: Use flow rates Qmax, Qt, Qmin (from Table 3, IS 779:1994) and Qn (from Table 2, IS 779:1994).

• Test Procedure:

  • Adjust inlet/outlet valves to achieve desired flow rates.
  • Record meter reading at start and end for each flow rate.
  • Collect water volume in measuring tank simultaneously.

• Error Calculation Formula:
  [ \text{Percent error} = \frac{V_1 - V_2}{V_2} \times 100 ] where,
  (V_1) = volume collected in tank,
  (V_2) = volume indicated by meter.

• Test Reporting:

  • Report accuracy separately for each discharge (Qmax, Qt, Qmin, Qn).
  • Qn test is optional (per purchaser).
  • Volume recorded at Qmin confirms minimum starting flow compliance.

• Additional Notes:

  • Life test and wear inspection per Clause 9.3.
  • Test report format as per Annex A.

Summary Table (Flow Rates from IS 779:1994)

This ensures meter accuracy is verified across operational range, critical for billing and system performance.

IS 6784: Pressure Tightness Test Key Points

Pressure Tightness Test (Clause 6.2.2.4)

• Test Pressure: 2.0 MPa (20 bar)
• Duration: 1 minute
• Purpose: Verify no leakage under specified pressure

Test Equipment (Clause 3.3)

• Use hand pumps, reciprocating pumps, pressure intensifiers, or dead weight pressure gauge testers for applying pressure.
• Equipment must be capable of maintaining test pressure steadily.

Procedure Summary

• Fill the test specimen with water.
• Apply test pressure of 2.0 MPa.
• Maintain pressure for 1 minute.
• Inspect for leaks or pressure drop.

Additional Test Equipment for Related Tests

Quick Formula for Pressure Test Setup

[ P_{test} = 2.0 \text{ MPa} = 20 \text{ bar} ]

flowchart LR
    A[Start: Fill specimen with water] --> B[Apply pressure using pump]
    B --> C{Pressure = 2.0 MPa?}
    C -- Yes --> D[Hold for 1 minute]
    D --> E[Check for leaks]
    E -- No leaks --> F[Pass]
    E -- Leaks --> G[Fail]

Summary: Use suitable pumps to apply 2.0 MPa pressure for 1 minute, ensuring no leakage. Equipment must maintain pressure steadily.

IS 6784: Temperature Suitability Test Summary

Test Procedure (Clause 8.2)

• Use a meter qualified per IS 779:1994.
• Place meter in test equipment at 45°C ± 1°C.
• Duration: 10 hours.
• Remove dust cap or water-blocking device on wet chamber during immersion.

Life Test (Clause 9.1 & Table 1 Summary)

• Qn = Nominal flow rate (kl/h).

Post-Test Inspection (Clause 9.3)

• Dismantle meter (preferably the one with max performance deterioration).
• Check for wear/distortion on:
  • Vane wheel/piston
  • Impeller shaft & measuring chamber
  • Bearings, gears, pinions, pivots
  • Gland packing

Test Report (Annex A)

• Include meter details: maker, type, class, size.
• Record flow ratings, pressure loss, metering accuracy errors.
• Document pressure tightness test results.

flowchart LR
    A[Qualified Meter per IS 779] --> B[Temperature Suitability Test: 45°C ±1°C for 10 hrs]
    B --> C[Remove dust cap/water seal]
    C --> D[Life Test per Table 1]
    D --> E[Post-Test Dismantling & Inspection]
    E --> F[Test Report Compilation (Annex A)]

Key Points:

• Temperature

IS 6784: Life Test (Accelerated Endurance Test) Key Points

1. Test Procedure (Clause 9.1 & Table 1)

• Samples: Two unopened meters per size/class every 6 months.
• Test Types: Discontinuous or continuous depending on nominal flow rate (Qn).
• Test Flow Rates & Duration:

• Qn: Nominal flow rate in kl/h.

2. Equipment (Clause 5)

• Centrifugal pump with regulating valves.
• Horizontal test bench.
• Pressure gauge.

3. Post-Test Examination (Clause 9.3)

• Dismantle one meter (preferably with greater deterioration).
• Check wear on vane wheel/piston, impeller shaft, bearings, gears, pivots, gland packing.

4. Temperature Suitability Test (Clause 8.2.1)

• 10 hours immersion at 45°C ± 1°C.
• Acclimatize to ambient temperature.
• Test flow and pressure tightness post-immersion.

Summary Diagram of Life Test Flow

flowchart TD
    A[Select 2 unopened meters] --> B{Nominal Flow Rate ≤ 10?}
    B -- Yes --> C[Discontinuous Test @ Qn]
    B -- No --> D[Continuous Test @ Qn or 2Qn]
    C --> E[100,000 Interruptions, 15s pauses]

IS 6784 - Test Report Key Points & Specifications

Test Report Format (Annex A)

• Meter Details: Maker, Type, Class, Meter No., Size (mm)
• Performance Parameters:

Test Equipment Summary

• Pressure Tightness: Hand pump, reciprocating pump, or pressure intensifier (Clause 3.3)
• Temperature Suitability: Container with heating elements, temperature control at 45°C ±1°C (Clause 4)
• Life Test: Centrifugal pump, regulating valves, horizontal test bench, pressure gauge (Clause 5)

Additional Notes

• Final test values must be rounded as per IS 2:1960.
• After life test, dismantle meter to check wear on actuating units, shafts, bearings, gears, pivots, gland packing (Clause 9.3).

flowchart LR
    A[Test Setup] --> B[Pressure Tightness Test]
    A --> C[Temperature Suitability Test at 45°C ±1°C]
    A --> D[Life Test with Centrifugal Pump]
    D --> E[Dismantle & Examine Wear]
    B --> F[Pressure 2.0 MPa for 1 min]
    C --> G[Heating Container + Temp Control]

This structure ensures comprehensive validation of meter performance and durability per IS 6784.

IS 6784: Test Report for Water Meter - Key Points

1. Test Report Format (Annex A)

• Meter details: Maker, Type, Class, Meter No., Size (mm)
• Flow ratings and pressure losses:
  • Maximum flow rating (Qmax)
  • Nominal flow rating (Qn)
  • Transitional flow rating (Qt)
  • Minimum starting flow rating (Qmin)
• Parameters to report per flow rate:
  • Pressure loss (MPa)
  • Metering accuracy error (%)

2. Metering Accuracy Test (Clause 6.1)

• Flow rates tested per IS 779:1994 (Qmax, Qt, Qmin, Qn)
• Procedure:
  • Record volume at start and end of test
  • Compare meter volume (V2) with actual volume collected (V1)
• Error formula:

[ \text{Percent error} = \frac{V1 - V2}{V2} \times 100 ]

Where:

• (V1) = Volume collected in tank
• (V2) = Volume indicated by meter

3. Wear Examination (Clause 9.3)

• After life test, dismantle meter showing max deterioration
• Inspect vane wheel/piston, impeller shaft, bearings, gears, pinions, pivots, gland packing for wear/distortion

4. Pressure Tightness Test

• Conducted as per specified clause (details in IS 6784)

flowchart TD
    A[Start Test] --> B[Set flow rate (Qmax, Qt, Qmin, Qn)]
    B --> C[Record meter reading at start]
    C --> D[Pass water through meter]
    D --> E[Record meter reading at end]
    E --> F[Collect actual volume in tank]
    F --> G[Calculate % error]
    G --> H{Error acceptable?}
    H -- Yes --> I[Pass test]
    H -- No --> J[Fail test]

Summary: Use Annex A format for reporting; test accuracy at specified flow rates per IS 779; calculate error using volume comparison; inspect meter components post life test for wear.

IS 6784 - Committee Composition Overview

• The committee responsible for IS 6784 is the Sanitary Appliances and Water Fittings Sectional Committee, CED 3.
• The detailed committee members and their affiliations are listed in Annex B of the standard.
• Key roles include:
  • Chairman: Shri S. Prakash (Delhi Water Supply & Sewage Disposal Undertaking)
  • Numerous members from government bodies, research institutes (CSIR), industry manufacturers, and public health engineering departments.
• The committee also includes a Water Meters Subcommittee with its own convener and members from related industries and government departments.

Important Notes:

• Final test values should be rounded off per IS 2:1960 rules, maintaining significant figures as per the standard.
• No specific formulas or tables for committee composition are provided; the Annex B serves as the official reference.

Summary Table (Excerpt of Committee Composition)

graph TD
A[IS 6784 Committee] --> B[Chairman: Shri S. Prakash]
A --> C[Members]
C --> D[Govt. Agencies]
C --> E[Research Institutes (CSIR)]
C --> F[Manufacturers]
C --> G[Public Health Engineers]

For full details, refer to Annex B of IS 6784.