GB/T 29730-2025 in English

GB/T29730-2025 Standard Revision Background and Technological Evolution

The GB/T29730-2025 national standard, "Manifolds for Hot and Cold Water," marks the first comprehensive revision of the 2013 edition, reflecting changes in technological development and market demand in my country's HVAC industry. This revision not only includes structural adjustments and editorial changes, but also achieves significant breakthroughs in technical content.

Major Technical Changes and Innovations

Compared to the 2013 edition, the new standard has undergone 11 major technical adjustments:

Classification and marking system for manifolds

Chapter 4 of the standard clarifies the systematic classification method for manifolds:

Classification by material:Copper alloy manifolds (code C), stainless steel manifolds (code S), plastic manifolds (Code P)

Classification by connection method:Internal thread connection (code F), external thread connection (code M), flange connection (code FL)

Marking example: DM-CF-25×20-4 indicates a manifold made of copper alloy, internal thread connection, main pipe DN25, branch pipe DN20, and 4-way branch pipes

Material requirements and quality control

Chapter 5 of the standard sets clear requirements for manifold materials:

Copper alloy manifold Machining materials and hot forging materials must meet the requirements of GB/T5231 or YS/T583, and the lead brass material must not be lower than HPb59-1 grade

Stainless steel manifold The main material must meet the requirements of S11972, S30408 and other grades in GB/T12771

Plastic manifolds can be made of a variety of materials, including PE, PP, PB, and ABS, but must comply with relevant product standards.

Detailed Explanation of Key Performance Requirements

Hydraulic Balance Performance (Clause 6.6)

When the valves on each branch of the manifold are fully open, the flow uniformity requirement is: $$\frac{q_{1}-q_{2}}{q_{1}+q_{2}}\times100\%\leqslant7.5\%$$

This indicator ensures balanced flow distribution across the system branches and avoids hydraulic imbalance.

Flow Regulation Performance (Clause 6.7)

When the manifold regulating valve is 25% open, the flow rate must not exceed 30% of the fully open flow rate, and when it is 50% open, it must not exceed 70% to ensure linear regulation characteristics.

Mechanical Performance Requirements

Innovation in detection and test methods

The new version of the standard adds systematic test conditions (Clause 7.1) to ensure the comparability and accuracy of the test results:

Test medium: air at room temperature and clean water at 5℃~40℃

Measuring instrument accuracy: not less than Class 1.0

New test methods such as salt spray test, torsion test and pull-out resistance test have been added to improve the product quality evaluation system.

Inspection rules and quality control

Chapter 8 of the standard specifies the specific requirements for factory inspection and type inspection:

Factory inspection items:Appearance, dimensions and connections, and air tightness are mandatory inspection items

Type inspection timing:Must be carried out when new products are finalized, materials and processes are significantly changed, regular inspections are carried out, production is suspended and resumed, etc.

The sampling plan is implemented in accordance with GB/T2828.1, using the special inspection level S-3 and a single sampling plan for normal inspection with an AQL of 6.5

Implementation suggestions and application guidance

Design selection suggestions

Reasonably select the type of manifold according to system requirements: Copper alloy manifolds are suitable for high temperature and high pressure occasions, with an operating temperature of 5-85°C; plastic manifolds are suitable for medium and low temperature systems, with an operating temperature of 5-85°C; Operating temperature 5-60℃

Installation and Use Precautions

Rubber gaskets should be installed on the contact part between the fixing bracket and the manifold body to avoid electrochemical corrosion caused by direct metal contact

The number of branch pipes should follow the standard recommendations: DN25 should not exceed 6, DN32 should not exceed 9, DN40 should not exceed 12, and DN50 should not exceed 15

Key Points for Quality Acceptance

Focus on checking key indicators such as air tightness, pressure strength, and hydraulic balance performance to ensure that the product meets the standard requirements

For automatically controlled manifolds, it is also necessary to verify that the performance of the electric actuator or electric actuator meets the requirements of QB/T5788 or GB/T14536.1

Impact of Standard Implementation and Industry Significance

The implementation of GB/T29730-2025 will have a profound impact on the HVAC industry:

1. 1. Improve product quality and regulate market competition. 2. Promote technological innovation and advance the development of intelligently controlled manifolds. 3. Improve the testing and certification system to ensure project quality. 4. Align with advanced international standards to enhance product competitiveness. Manufacturing companies should familiarize themselves with the new standards as quickly as possible and complete product upgrades and technological transformations. Design firms should conduct system design and equipment selection in accordance with the new standards. Project quality supervision departments should strengthen market supervision and product spot checks based on the new standards.