pressure-reducing valves for domestic water supply systems

IS 9739 - Scope: Key Specifications and Tables

Scope Summary (Clause 0.2)

• Applies to pressure reducing valves (PRVs) for domestic water supply.
• PRVs reduce high inlet pressure (up to ~1.72 MPa) to a safe, usable outlet pressure.
• Ensures protection of downstream equipment by controlling fluid pressure economically.

Key Materials (Clause 3.1, Table 1)

Performance Requirements (Clause 5.3, Table 2)

• Minimum reduced pressure: 0.17225 MPa at inlet pressure 1.7225 MPa.
• Flow capacities by nominal size:

Notes:

• Final test values rounded per IS 2:1960.
• Thread sizes per IS 554:1975.

flowchart LR
    A[High Pressure Water] -->|Inlet Pressure ~1.72 MPa| B[Pressure Reducing Valve]
    B -->|Reduced Pressure ~0.17 MPa| C[Domestic Water Supply]
``

IS 9739 - Nominal Sizes for Pressure Reducing Valves

• Nominal Size Definition (Clause 2.2):
  The nominal size of the valve corresponds to the nominal bore (NB) of the pipe it connects to.

• Standard Nominal Sizes (Clause 2.1):

  Nominal Size (mm)	Nominal Size (inch)
  15	1/2"
  20	3/4"
  25	1"
  32	1 1/4"
  40	1 1/2"
  50	2"

• Threaded Ends (Clause 554.1975 Note):
  Thread sizes and designations follow IS 554:1975, which standardizes pipe threads.

Summary Diagram of Nominal Size Relation

graph LR
A[Pipe Nominal Bore] --> B[Valve Nominal Size]
B --> C{Standard Sizes}
C --> D[15 mm (1/2")]
C --> E[20 mm (3/4")]
C --> F[25 mm (1")]
C --> G[32 mm (1 1/4")]
C --> H[40 mm (1 1/2")]
C --> I[50 mm (2")]

Note: Nominal size is a designation, not the exact internal diameter; actual dimensions vary per IS pipe standards.

IS 9739 — Materials for Pressure Reducing Valves (Clause 3.1 & Table 1)

Additional Performance Data (Clause 5.3 & Table 2)

• Minimum Reduced Pressure: Valve adjustable to as low as 0.17225 MPa at inlet pressure 1.7225 MPa.

Summary

• Use Leaded-tin bronze (IS 318 Grade 2) for main valve body parts.
• Cast iron FG 200 (IS 210) for diaphragm covers.
• Critical parts like valve stem use

IS 9739: Construction and Workmanship - Key Specifications

1. Materials for Components (Clause 3.1, Table 1)

2. Workmanship (Clause 4.7)

• Valves must allow repair or removal of parts without breaking the pipeline or removing the valve.
• Threaded joints must conform to IS: 554-1975 for pressure-tight pipe threads.

Summary:

• Use specified materials for each valve component as per Table 1.
• Design valves for easy maintenance without pipeline disruption.
• Follow IS standards for threads and materials to ensure pressure tightness and durability.

flowchart TD
    A[Valve Components] --> B[Material Selection]
    B --> C[Leaded-tin bronze]
    B --> D[Cast iron FG 200]
    B --> E[Chromium steel]
    B --> F[Others (Steel, Asbestos fibre, Stainless steel)]
    A --> G[Workmanship]
    G --> H[Repair without pipeline break]
    G --> I[Pressure-tight threaded joints per IS 554]

This ensures valve reliability and ease of maintenance as per IS 9739.

IS 9739: Performance Requirements for Pressure Reducing Valves

Key Formulas & Specifications

• Minimum Reduced Pressure (Clause 5.3):
  When flow rate = Table 2 value, and inlet pressure = 1.7225 MPa, valve must adjust reduced pressure as low as 0.17225 MPa.

• Capacity Requirement (Clause 5.5):
  Valve capacity at reduced pressure =

  • Reduced pressure = no-flow set pressure - 0.1171 MPa
  • Inlet pressure = reduced pressure + 0.3445 MPa
    Minimum capacity as per Table 2.

Table 2: Capacities of Pressure Reducing Valves

Materials (Clause 3.1)

Additional Notes

• Strainer Screen (Clause 4.9):
  Open flow area ≥ 2 × nominal pipe flow area
  Max hole size ≤ 1/12 valve orifice diameter

flowchart LR
    A[Inlet Pressure: 1.

IS 9739: Test Procedures for Pressure Reducing Valves

Key Clauses & Specifications

• Clause 6.2: Test for Reduced Pressure Deviation
  Measures valve’s ability to maintain reduced pressure within allowable deviation under varying flow conditions.

• Clause 6.5: Capacity Test
  Valve capacity must meet Table 2 values while maintaining:

  • Reduced pressure = Set pressure - 0.1171 MPa
  • Inlet pressure = Reduced pressure + 0.3445 MPa

Table 2: Minimum Capacity (Example format, refer IS 9739 for exact values)

Materials (Clause 3.1, Table 1)

Summary Diagram: Test Procedure Flow

flowchart TD
    A[Start Test] --> B[Set inlet pressure = Reduced pressure + 0.3445 MPa]
    B --> C[Set reduced pressure = No-flow set pressure - 0.1171 MPa]
    C --> D[Measure flow rate]
    D --> E{Is flow rate ≥ Table 2 capacity?}
    E -- Yes --> F[Pass Capacity Test]
    E -- No --> G[Fail Capacity Test]
    F --> H[Check Reduced Pressure Deviation (Clause 6.2)]
    G --> H
    H --> I[End Test]

Note: Refer to IS 973

IS 9739: Key Instructions & Specifications for Pressure Reducing Valves

Clause 7.1: Instructions

• Every pressure reducing valve must include instructions for:
  • Installation
  • Adjustment
  • Maintenance

Materials for Components (Clause 3.1, Table 1)

Important Notes

• Use IS:2-1960 for rounding off test values.
• Pressure reducing valves are designed to reduce and regulate fluid pressure economically.
• Testing setup example shown in Fig. 3 (flow meter, supply valve, throttle valve).

Summary Diagram: Installation & Maintenance Flow

flowchart TD
    A[Receive Valve] --> B[Read Instructions]
    B --> C[Install Valve Correctly]
    C --> D[Adjust Pressure Settings]
    D --> E[Perform Testing]
    E --> F[Regular Maintenance]

For detailed design or testing formulas, refer to IS 9739 full text and related IS codes for materials and testing procedures.

IS 9739 - Marking of Pressure Reducing Valves (Clause 8.1 & 8.1.1)

Key Specifications:

• Mandatory Marking:

  • Manufacturer's name or trade mark.
  • Nominal size of the valve.

• Optional Marking:

  • ISI Certification Mark (subject to licensing under Indian Standards Institution Act).

Purpose of ISI Mark:

• Assurance of compliance with IS standards.
• Implies regular inspection, testing, and quality control.
• Continuous conformity checks by ISI.

Summary Table for Marking Requirements

Additional Notes:

• The ISI Mark is governed by the Indian Standards Institution (Certification Marks) Act.
• Marking should be permanent and legible on the valve body.
• Marking ensures traceability and quality assurance.

flowchart LR
    A[Pressure Reducing Valve] --> B{Marking}
    B --> C[Manufacturer's Name/Trade Mark]
    B --> D[Nominal Size]
    B --> E[ISI Certification Mark (Optional)]
    E --> F[Licensing & Quality Control by ISI]

This ensures valves comply with IS 9739 quality and traceability norms.