ASSE/ANSI 1057-2023
Performance Requirements for Freeze Resistant Sanitary Yard Hydrants with Backflow Protection
- Standard No.
- ASSE/ANSI 1057-2023
- Release Date
- 2023
- Published By
- American National Standards Institute （ANSI)
- Latest
- ASSE/ANSI 1057-2023
- Introduction
Analysis of the Technical Framework of ASSE 1057-2023
ASSE/ANSI 1057-2023, "Performance Requirements for Frost-Resistant Sanitary Yard Hydrants with Backflow Protection," is the latest standard version officially approved by the American Society of Sanitary Engineers (ASSE) in November 2023. This standard establishes systematic technical requirements for the frost protection and backflow protection of yard hydrants in cold environments, aiming to prevent cross-contamination and freezing damage to drinking water systems caused by the use of yard hydrants.
Scope of Standard Application and Equipment Classification
This standard applies to frost-resistant sanitary yard hydrants with an operating pressure range of 20-100 psi (138-689 kPa) and a water flow temperature of 33-140°F (4.4-60°C). According to the difference in antifreeze mechanism and anti-backflow structure, the standard divides the equipment into 5 types:
Type Number of check valves Atmospheric exhaust port Antifreeze condition Hose requirements Type 1 2 Yes When hose is connected No need to remove Type 2 2 Yes When hose is removed Need to remove Type 3 1 Yes When hose is connected Does not need to be removed Type 4 1 Yes When hose is removed Requires removal Type 5 At least 1 Yes Remove backflow preventer Do not connect
Key Technical Performance Test Requirements
Hydrostatic Pressure Test
All frost-proof yard fire hydrants must withstand 200 psi (1379 kPa) or twice the manufacturer's maximum rated working pressure for 5 minutes without leakage. This test verifies the structural integrity of the equipment under abnormally high pressure.
Freeze Resistance Test
After being exposed to a low temperature environment of 0°F (-17.8°C) for 60 minutes, the equipment must be able to drain normally at a flow rate of at least 3.0 GPM (0.2 L/s). During this test, the portion of the equipment above the frost line is placed in a low-temperature chamber, while the portion below the frost line is maintained at room temperature to simulate the actual installation environment.
Backflow Prevention Test System
The standard establishes a complete backflow prevention test procedure, including:
- Inlet Check Valve Backflow Prevention Test (Type 1 and 2): With the vent sealed and the outlet check valve held open, apply 10 feet (3.0 meters) of water head back pressure
- Outlet Check Valve Backflow Prevention Test (All Types): Verify there is no leakage at 10 feet of back pressure
- Anti-Siphon Test: After plugging all check valves with a 0.032-inch (0.813 mm) contamination line, apply a 25-inch Hg (84.7 kPa) vacuum
Test Items Test Pressure Duration Acceptance Criteria Hydrostatic Pressure 200 psi or 2 times working pressure 5 minutes No external leakage Life Cycles 100 psi working pressure 5000 cycles No performance degradation Bend Resistance 100 lbs lateral pull 3 minutes No leakage or rupture Flow Performance 25 psi pressure drop Steady State 3/4" port ≥4 GPM
Material and Manufacturing Requirements
Chapter 4 of the standard sets clear requirements for material selection: Solders and fluxes in contact with drinking water must not contain more than 0.2% lead; and the corrosion resistance of internal moving parts must be at least equivalent to that of alloys containing at least 58% copper. These requirements ensure the hygienic safety of the equipment during long-term use.
Installation and Maintenance Specifications
The standard emphasizes that frost-resistant yard fire hydrants must be installed by trained professionals, and that repair and replacement of elastic components after installation must not require excavation of the surrounding soil. Each device should be accompanied by detailed installation, operation, and maintenance instructions, including:
- Correct installation depth and frost protection measures
- Winter anti-freeze operating procedures
- Regular inspection and maintenance requirements
- Fault diagnosis and component replacement guide
Marking and Certification Requirements
Each device must be clearly marked with the manufacturer's name/trademark and the device type and model in a visible location after installation. The marking should be cast, etched, stamped or engraved, or a firmly fixed nameplate made of corrosion-resistant material. Only products that have passed ASSE testing and obtained certification may use the ASSE logo.
Standard Implementation Recommendations
Design Selection Recommendations
Select the appropriate device type based on the operating environment and climatic conditions: Type 1 or Type 3 devices are recommended in cold regions. These types can provide anti-freeze protection when the hose is connected and do not require frequent disassembly; Type 2 or Type 4 devices can be selected in mild climates.
Installation Precautions
During installation, ensure that the part below the frost line is fully buried and the part above the frost line is maintained at an appropriate height; the inlet connection must use a pipe thread that complies with ASME B1.20.1, and the outlet connection must use a 3/4" or 1" garden hose connector that complies with ASME B1.20.7.
Maintenance and Inspection Cycle
It is recommended to conduct a functional inspection every six months, including: backflow prevention device performance test, exhaust port patency check, and seal condition assessment. A complete antifreeze performance verification must be carried out before the arrival of winter.
Technological Evolution and Standard Development
Since its initial publication in 1993, the ASSE 1057 standard has undergone three major revisions in 2001, 2012, and 2023. The main updates to the 2023 edition include: detailed equipment classification, strengthened backflow prevention testing requirements, improved material specifications, and the addition of electronic instruction manual requirements. These revisions reflect the industry's technological advancements and increased safety management requirements.
This standard, together with backflow preventer standards such as ASSE 1011 and ASSE 1019, constitutes a drinking water safety protection system, providing complete technical specifications for the safe use of courtyard water supply equipment. With the development of water-saving technologies and intelligent control technologies, the standard may incorporate new requirements such as flow control and remote monitoring in the future.
ASSE/ANSI 1057-2023 history
- 2023 ASSE/ANSI 1057-2023 Performance Requirements for Freeze Resistant Sanitary Yard Hydrants with Backflow Protection
