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ANSI Z21.78-2010 / CSA 6.20-2010: Standard for Manually Operated Gas Valves for Appliances, Connector Valves and Hose End Valves
Comprehensive guide to scope, technical requirements, and compliance of the joint US-Canada gas valve safety standard
The joint standard ANSI Z21.78-2010 (R2015) / CSA 6.20-2010 establishes uniform requirements for the construction, performance, and marking of manually operated gas valves used in conjunction with gas appliances, appliance connector valves, and hose end valves. Developed collaboratively by the American National Standards Institute (ANSI) and the Canadian Standards Association (CSA), this standard ensures that valves operating with natural gas, manufactured gas, mixed gas, liquefied petroleum gases (LP-gas), and LP-gas-air mixtures meet minimum safety and reliability criteria for residential and commercial applications across North America.
Scope and Purpose
The standard applies to manually operated valves intended for use with gas appliances and appliance connectors where the valve is directly connected to the appliance or to a gas supply line via a connector. It covers valve types including straight-through, two-way, and three-way configurations, with inlet and outlet connections not exceeding NPS 2 (DN 50). Valves rated for a maximum working pressure of 1/2 psi (3.5 kPa) or 5 psi (34.5 kPa) are addressed, with corresponding classifications for low-pressure and high-pressure applications.
The purpose is to define consistent safety and performance benchmarks that protect end-users from gas leakage, mechanical failure, and fire hazards. The standard is referenced by numerous appliance and system installation codes, including the National Fuel Gas Code (NFPA 54) and the Canadian CSA B149 series.
North American Harmonization: ANSI Z21.78-2010 and CSA 6.20-2010 are technically identical, allowing manufacturers to satisfy both U.S. and Canadian regulatory requirements with a single design and testing regimen. This dual designation reduces certification burden and facilitates market access across the border.
Technical Requirements and Performance Criteria
The standard imposes stringent requirements on materials, design, construction, and operational characteristics. All wetted parts must be corrosion-resistant and compatible with the intended gas composition. Valves must be designed so that the operating handle provides clear visual indication of the open and closed positions, and the valve may be equipped with or without a limiting orifice.
Leakage and Pressure Integrity
Two leak test regimes are specified: a low-pressure seat leakage test at 6 in. w.c. (1.5 kPa) and a high-pressure seat leakage test at 15 psi (103 kPa) for Class II valves. Acceptable leakage rates are strictly limited to ensure negligible gas escape. Additionally, a hydrostatic strength test requires the valve body to withstand 3 times its maximum rated pressure without rupture or permanent deformation.
Cycle Life and Torque
Valves must endure 6,000 full open-close cycles without any increase in leakage beyond the specified limit. The operating torque required to actuate the valve must not exceed 15 lbf·in (1.7 N·m) for sizes up to NPS 1, with progressive limits for larger diameters. This ensures ease of manual operation even after extended service life.
| Test | Condition | Acceptance Criterion |
|---|---|---|
| Low-pressure seat leakage | Air or inert gas at 6 in. w.c. (1.5 kPa) | ≤ 0.06 ft³/h (1.7 L/h) |
| High-pressure seat leakage (if applicable) | Air or inert gas at 15 psi (103 kPa) | ≤ 0.04 ft³/h (1.1 L/h) |
| Hydrostatic strength | Water at 3 × maximum rated pressure | No rupture or visible distortion |
| Cycle life | 6,000 full cycles at ambient temperature | No leakage increase beyond initial acceptance limits |
| Operating torque | Maximum during cycling test | ≤ 15 lbf·in (1.7 N·m) for ≤ NPS 1; higher limits per standard table |
Marking and Documentation
Each valve must be permanently marked with the manufacturer’s name or trademark, the model designation, the flow arrow, the word “GAS” or equivalent, the pressure class (if other than 1/2 psi), the date code, and the certification mark of a recognized third-party agency (e.g., CSA or AGA). Instructions for installation and maintenance must be provided, including torque values for pipe connections.
Tip for Design Engineers: When selecting materials, consider both corrosion resistance and thermal expansion compatibility. Valves with plastic components must pass additional dimensional stability tests at elevated temperatures (150°F / 66°C) to prevent warpage that could affect seal integrity.
Implementation Highlights for Manufacturers
Manufacturers seeking compliance should incorporate design features that facilitate low leakage over the valve lifespan. Key design aspects include precision-machined seating surfaces, resilient or metal-to-metal seals that are tested for compatibility with gas additives (e.g., odorants), and handle-to-stem connections that resist tampering. The standard also requires that the valve remain leak-free when subjected to external loads, such as pipe wrench torque during installation.
Quality assurance programs must include routine production leak testing and periodic comprehensive tests at qualified laboratories. Many manufacturers opt for the CSA certification program, which includes initial type testing and annual factory inspections to verify continued conformity.
Common Non-Compliance Issue: Inadequate marking of pressure class and gas type is a frequent reason for certification failure. Ensure that marking is legible, permanent, and applied in a location visible after installation. The use of adhesive labels is generally prohibited unless the adhesive is proven to be durable and the label securely affixed.
Compliance and Certification Notes
ANSI Z21.78-2010 (R2015) / CSA 6.20-2010 is a safety standard recognized by code enforcement authorities in the United States and Canada. While the standard itself is voluntary, compliance is effectively mandatory because building codes and appliance standards (e.g., UL 21, CSA C22.2 No. 0) require that gas valves carry certification to this standard.
Third-party certification agencies such as CSA Group, Underwriters Laboratories (UL), or Intertek (ETL) evaluate samples to all applicable requirements. It is important to note that the standard includes both design review and witnessed testing; the manufacturer must maintain documented evidence of compliance for each production run. Revisions to the standard may occur; users should verify that the edition referenced in local codes is current. As of this writing, the 2010 edition reaffirmed in 2015 remains widely accepted.
Safety Alert: Gas valves that fail to meet the leakage and cycle life requirements of this standard pose an immediate fire and explosion risk. Never install unlisted or uncertified valves in gas supply lines. Always confirm that the certification mark matches the valve’s date of manufacture to avoid using revoked or superseded certifications.
Frequently Asked Questions
Q: What is the difference between Class I and Class II valves in ANSI Z21.78?
A: Class I valves are rated for a maximum working pressure of 1/2 psi (3.5 kPa) and typically used for indoor appliance connections. Class II valves are rated for up to 5 psi (34.5 kPa) and are intended for higher-pressure supply systems, requiring additional high-pressure seat leakage testing. Both classes must meet the same cycle life and low-pressure leakage requirements.
A: Class I valves are rated for a maximum working pressure of 1/2 psi (3.5 kPa) and typically used for indoor appliance connections. Class II valves are rated for up to 5 psi (34.5 kPa) and are intended for higher-pressure supply systems, requiring additional high-pressure seat leakage testing. Both classes must meet the same cycle life and low-pressure leakage requirements.
Q: Does the standard require integral shutoff or limiting orifices?
A: No, the standard does not mandate a limiting orifice or flow-control feature. However, if such a feature is incorporated (e.g., a stop restricting full opening), it must be clearly marked and its effect on flow capacity documented. The valve must still be manually operable to a full-open position unless labeled otherwise.
A: No, the standard does not mandate a limiting orifice or flow-control feature. However, if such a feature is incorporated (e.g., a stop restricting full opening), it must be clearly marked and its effect on flow capacity documented. The valve must still be manually operable to a full-open position unless labeled otherwise.
Q: Is ANSI Z21.78-2010 still current? Is there a newer edition?
A: The 2010 edition was reaffirmed in 2015 (R2015) and remains the current version as of 2026. A draft revision was circulated in 2022, but no new edition has been formally released. Always check the latest code adoption by local authorities, as some jurisdictions may have amended requirements.
A: The 2010 edition was reaffirmed in 2015 (R2015) and remains the current version as of 2026. A draft revision was circulated in 2022, but no new edition has been formally released. Always check the latest code adoption by local authorities, as some jurisdictions may have amended requirements.
Q: Are hose end valves covered by this standard?
A: Yes, the standard specifically includes hose end valves—i.e., valves attached to the free end of a flexible gas connector to allow connection to an appliance or manifold. These valves must meet the same performance requirements, with additional attention to sealing at the hose inlet fitting and resistance to bending loads.
A: Yes, the standard specifically includes hose end valves—i.e., valves attached to the free end of a flexible gas connector to allow connection to an appliance or manifold. These valves must meet the same performance requirements, with additional attention to sealing at the hose inlet fitting and resistance to bending loads.
Last updated: 2026