Explore our high-precision refrigeration accessories engineered to international standards.
Founded in 1988, Ningbo Taojun Refrigeration Equipment Co., Ltd. traces its roots back to the prestigious Xiangshan Refrigeration Accessories Factory of Zhejiang University. Over more than three decades of continuous R&D and supply chain integration, we have evolved into a national high-tech enterprise, specializing in design, development, high-precision manufacturing, and global sales of premium refrigeration and HVAC components.
Our expansive product catalog features industry-leading solutions, including specialized copper filter driers, condensers, check valves, brass and copper fittings, and our key structural offering: the 4mm Bundy Tube. With standard and customized designs, our components support home appliances and industrial systems worldwide.
In 2021, Taojun was recognized as a National High-Tech Enterprise, reinforcing our ongoing commitment to process improvement and technological innovation.
Bundy tubes, or double-walled low-carbon steel tubes, are key to modern refrigeration and automotive systems. Our 4mm Bundy tubes are engineered to deliver reliable hermetic sealing, thermal efficiency, and burst resistance.
Our 4mm Bundy tubes are manufactured by continuously strip-forming a copper-coated low-carbon steel strip into a double-wrapped cylinder, which is then brazed at high temperatures in a reducing atmosphere. This process yields a unified, concentric tube with consistent mechanical properties.
Key standards compliance: Our tubes fully conform to ASTM A254 and EN 10139 guidelines, ensuring consistent performance for high-vibration and high-pressure refrigeration circuits.
| Physical Parameter | Standard Value (4mm OD) | Testing Protocol / Compliance |
|---|---|---|
| Outer Diameter (OD) | 4.00 mm (±0.08 mm tolerance) | Micrometric verification, laser sizing |
| Wall Thickness | 0.50 mm - 0.70 mm | Ultrasonic wall thickness measurement |
| Tensile Strength | ≥ 290 MPa | ASTM E8 tensile testing protocol |
| Yield Strength | ≥ 180 MPa | Permanent deformation threshold evaluation |
| Internal Cleanness | ≤ 0.16 g/m² residue | Solvent extraction and gravimetric assessment |
| Brazing Coating Thickness | ≥ 3 μm (Copper coating thickness) | Microscopic cross-sectional profiling |
Combining structural cost advantages with advanced digital process control to maintain supply chain continuity for global OEMs.
First implemented in 2008, our Manufacturing Execution System (MES) monitors production status from raw materials to finished items, ensuring traceability across all manufacturing batches.
We use automated inline eddy current testing, CCD visual inspection, and high-pressure helium leak detection to verify structural integrity and weld quality.
Based in Xiangshan, Ningbo, our facility provides direct access to Ningbo Port, enabling swift transport and delivery to international markets.
As the refrigeration and automotive industries adapt to environmental updates and changing standards, Ningbo Taojun continues to update its production technologies.
Natural Refrigerant Compatibility (CO2 & Propane R290): The adoption of eco-friendly refrigerants requires systems that can withstand higher operational pressures. We are refining our double-walled brazing methods to handle operating pressures up to 120 bar, supporting CO2 transcritical systems.
Advanced PVF (Polyvinyl Fluoride) & Epoxy Coating: To improve corrosion resistance without compromising thermal conductivity, we are introducing thin-layer organic coatings that exceed 1000-hour salt spray test requirements under ASTM B117 standards.
Providing custom solutions that comply with international technical and environmental standards for global manufacturing partners.
Supplying consistent, clean-bore 4mm Bundy tubes for evaporators, hot gas loops, and static wire-on-tube condensers utilized by leading brands like Haier, Midea, and Whirlpool.
Meeting automotive requirements for brake line assemblies, hydraulic systems, and fuel lines, where high mechanical strength under pressure is critical.
Providing high-performance coils and heat exchangers designed for commercial ice makers, walk-in cold rooms, and temperature-controlled logistics networks.
From a university-associated workshop in 1988 to a recognized high-tech manufacturing brand.
Founded as the Xiangshan Refrigeration Accessories Factory of Zhejiang University, starting our focus on technological innovation and component design.
Expanded our primary manufacturing facilities, introducing automated production lines and enhancing quality control systems.
Implemented the MES Intelligent Workshop Management System to digitize product traceability and process parameters.
Continued scaling of production, serving global partners and developing high-pressure, eco-refrigerant-ready tube technologies.
Our manufacturing facility maintains strict quality standards to ensure consistency and reliability for global shipments.
Our manufacturing facility in Zhejiang, China operates under the GB/T19001-2016 / ISO9001:2015 Quality Management System standard (Certificate Registration No.: 41325Q00065R0S). This certification, verified through China's CNCA (www.cnca.gov.cn), demonstrates our commitment to consistent quality across design and production phases.
For global environmental compliance, our components are certified to meet the requirements of the EU RoHS Directive, REACH, and the US UL safety standards.
CNAS Testing Laboratory Accreditation
EU RoHS Directive Certified
UL North America Standard Certified
IATF 16949 Quality Compliant
Providing high-precision components designed for cooling efficiency and structural reliability.
Detailed answers to technical questions about refrigeration tubing design, applications, and selection parameters.
Bundy tubes, or double-walled brazed steel tubes, provide higher tensile and yield strength than standard copper tubes, making them resistant to high pressures and structural fatigue. While copper has higher thermal conductivity, Bundy tubes offer a cost-effective, pressure-resistant alternative, particularly in automotive brake lines and static wire-on-tube refrigeration condensers.
Internal cleanliness is verified using a solvent-washing process followed by gravimetric assessment to ensure internal residue remains below 0.16 g/m², conforming to DIN 8964 standards. This process helps prevent capillary clogging and protects the compressor.
We offer several coating options based on application requirements, including standard copper electroplating (≥3μm), zinc plating with chromate passivation, PVF (Polyvinyl Fluoride) coating for harsh environments, and epoxy powder coatings.
Yes. Our CNC bending equipment and end-forming machinery support custom tolerances down to ±0.05 mm, enabling shapes like expansion bells, reductions, and custom flare fittings for quick integration into assembly lines.
Our standard production lead time is 15 to 25 days depending on batch volume. Located near Ningbo Port, we coordinate standard FOB, CIF, and DDP shipments to simplify international logistics.
Taojun
