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IS 14948:2001 Part 2 is the Indian Standard (BIS) for backflow prevention devices - reduced pressure zone type backflow preventers. This standard specifies the requirements for Reduced Pressure Zone (RPZ) backflow prevention devices. It details the materials, design, construction, performance criteria, and testing methods to ensure these devices effectively protect potable water systems from contamination in high-hazard applications.
Specifies requirements for reduced pressure zone type backflow preventers for potable water supply.
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! RPZ devices must be installed in locations with adequate drainage as they are designed to discharge water from the relief port during backflow events.
! Annual testing and certification by a qualified professional are critical to ensure the device remains functional and compliant.
! Installation must be done according to manufacturer's instructions and local plumbing codes, paying close attention to required orientation (usually horizontal) and clearances for testing and maintenance.
EN 1717:2000CEN (European Committee for Standardization), Europe
HighCurrent
Protection against pollution of potable water in water installations and general requirements of devices to prevent pollution by backflow
Defines Air Gaps (designated as Family A) as part of a comprehensive framework for backflow prevention.
ASME A112.1.2-2012 (R2022)ASME (American Society of Mechanical Engineers), USA
HighCurrent
Air Gaps in Plumbing Systems
A dedicated standard specifying the geometry, installation, and requirements for air gaps in plumbing.
AS/NZS 3500.1:2021Standards Australia / Standards New Zealand, Australia/New Zealand
HighCurrent
Plumbing and drainage, Part 1: Water services
Includes a section on backflow prevention that specifies requirements for registered and unregistered air gaps.
CSA B64.1.2-11 (R2021)CSA Group (Canadian Standards Association), Canada
HighCurrent
Air gaps for plumbing systems
Canadian standard harmonized with ASME A112.1.2, providing requirements for air gaps.
Key Differences
≠EN 1717 provides a detailed classification of air gaps (e.g., Type AA - free-flowing unrestricted, Type AB - with non-circular overflow) based on application and overflow characteristics. IS 14948 defines a single 'Verified Air Gap' without this level of sub-categorization.
≠The absolute minimum air gap dimension differs. IS 14948 specifies a minimum of 20 mm, whereas ASME A112.1.2 requires a minimum of 1 inch (25.4 mm), which is more stringent.
≠International standards like ASME A112.1.2 have specific rules for proximity to vertical surfaces (walls). If the supply outlet is closer than three times its diameter to a wall, the required air gap increases to three times the diameter. IS 14948 does not explicitly detail such a requirement.
≠EN 1717 integrates air gaps into a risk assessment framework using Fluid Categories 1 through 5, making the air gap mandatory for the highest risk (Category 5). IS 14948 recommends its use for 'seriously polluted water' but isn't explicitly tied to a standardized fluid risk classification system.
Key Similarities
≈All standards are based on the fundamental principle of a physical, vertical air break between the supply outlet and the flood level rim of the receiving fixture to prevent contamination.
≈The core formula for determining the minimum air gap is consistently defined as twice the internal diameter of the supply inlet pipe (2D) across all standards.
≈The concept of the 'Flood Level Rim' (the point at which a fixture or tank will overflow) is used universally as the critical lower reference point for measuring the air gap.
≈All standards recognize the air gap as the most effective and reliable method of backflow prevention, suitable for protection against the highest degrees of hazard.
Parameter Comparison
Parameter
IS Value
International
Source
Primary Sizing Rule
≥ 2 times the internal diameter of the supply pipe (2D)
≥ 2 times the effective diameter of the supply pipe (2D)
EN 1717
Absolute Minimum Gap Dimension
20 mm
1 inch (25.4 mm)
ASME A112.1.2
Air Gap Typology
One type: 'Verified Air Gap'
Multiple types based on overflow and trajectory (e.g., AA, AB, AC, AD)
EN 1717
Side Wall Proximity Rule
Not specified
If distance to wall < 3D, required gap becomes 3D
ASME A112.1.2
Application for High Hazard
For 'seriously polluted water'
For Fluid Category 5 (fluid representing a serious health hazard)
EN 1717
Measurement Reference
From lowest point of supply pipe outlet to the flood level rim.
From the lowest point of the orifice that supplies water to the flood level rim of the receptacle.
ASME A112.1.2
⚠ Verify details from original standards before use
Key Values5
Quick Reference Values
Relief valve opening pressure differentialMust open when zone pressure is 14 kPa (or less) above atmospheric pressure
First check valve pressure requirementMust be drip-tight in the direction of flow when the inlet pressure is 3.5 kPa or greater
Hydrostatic test pressureDevice body must withstand 2 times the maximum working pressure for 15 minutes without leakage
Maximum rated working pressure1.2 MPa
Maximum water temperature45 °C
Tables & Referenced Sections
Key Tables
Table 1: Dimensions of Backflow Preventers (Flanged Ends)
What is the primary purpose of an RPZ backflow preventer?+
To protect potable water supplies from contamination in high-hazard cross-connections where back-siphonage or back-pressure could introduce harmful substances. (Clause 1)
How does an RPZ device work?+
It uses two independently acting check valves with an intermediate reduced pressure zone and a differential pressure relief valve. If a pressure drop occurs, the relief valve opens to discharge water, creating an air gap and preventing backflow. (Clause 5.1)
At what pressure differential does the relief valve open?+
The relief valve must open and discharge to atmosphere when the pressure in the intermediate zone drops to 14 kPa or less above atmospheric pressure. (Clause 6.2)
Does this standard cover installation procedures?+
No, this standard is a product specification for the device itself. Installation requirements are covered by plumbing codes like the National Building Code (NBC) of India.