Stainless Steel Coil Tube for Fan Coil Units (FCU)
1. Product Overview
The Stainless Steel Coil Tube (Product No. 1609) is a precision-engineered coil tube manufactured by Wenzhou Jixing Metal Materials Co., Ltd., specifically designed for use in room air conditioning fan coil units (Fan Coil Units, FCU). This product complies with the national standard GB/T 19232 (Room Air Conditioner with Fan Coil Unit), ensuring reliable thermal exchange performance, structural integrity, and long-term operational stability in HVAC (Heating, Ventilation, and Air Conditioning) systems.
These coil tubes serve as the core heat exchanger components within fan coil units, facilitating efficient heat transfer between refrigerant and ambient air. Their compact spiral geometry maximizes the heat exchange surface area within a minimal footprint, making them indispensable in commercial and residential air conditioning applications.
2. Material and Properties
The coil tubes are fabricated from high-grade stainless steel, selected for its superior corrosion resistance, mechanical strength, and thermal conductivity. The primary material grades utilized include:
- 304 Stainless Steel (UNS S30400) — Austenitic stainless steel with excellent general corrosion resistance, ideal for standard HVAC environments.
- 316L Stainless Steel (UNS S31603) — Enhanced resistance to chlorides and pitting corrosion, suitable for marine or high-humidity environments.
Key material properties include:
- Tensile Strength: ≥ 520 MPa (304 grade); ≥ 485 MPa (316L grade)
- Yield Strength: ≥ 205 MPa
- Elongation: ≥ 40%
- Thermal Conductivity: 16.3 W/(m·K) at 20°C (304 grade)
- Operating Temperature Range: -200°C to +870°C
- Corrosion Resistance: Excellent resistance to atmospheric, chemical, and aqueous corrosion
3. Technical Specifications
| Parameter | Specification | Unit |
|---|---|---|
| Product Number | 1609 | — |
| Product Name | Stainless Steel Coil Tube (Fan Coil Unit) | — |
| Outer Diameter (OD) | 6.35 / 9.52 / 12.70 (customizable) | mm |
| Wall Thickness | 0.30 – 0.60 | mm |
| Coil Pitch (Turn Spacing) | 3.00 – 6.00 | mm |
| Number of Rows | 1 – 4 (configurable) | — |
| Tube Length per Row | 400 – 1200 | mm |
| Coil Diameter | 100 – 300 | mm |
| Operating Pressure | ≤ 1.6 (standard); ≤ 2.5 (high-pressure) | MPa |
| Refrigerant Compatibility | R22, R410A, R32, R134a, R407C | — |
| Surface Treatment | Electropolished / Passivated | — |
| Applicable Standard | GB/T 19232; ASHRAE Standard 34; EN 14511 | — |
4. Manufacturing Process
The production of these stainless steel coil tubes follows a rigorous multi-stage manufacturing process to ensure dimensional accuracy, surface integrity, and functional reliability:
- Material Selection and Inspection: Raw stainless steel coils are sourced from certified suppliers and subjected to spectroscopic analysis (e.g., XRF — X-ray Fluorescence) to verify chemical composition compliance with ASTM/EN standards.
- Pipe Drawing and Forming: Seamless stainless steel tubes undergo cold-drawing to achieve precise outer diameter and wall thickness tolerances (±0.05 mm).
- Coil Winding: The drawn tubes are mechanically coiled using CNC-controlled winding equipment, ensuring uniform pitch, consistent curvature radius, and minimal residual stress.
- Welding and Brazing: Header connections (inlet/outlet manifolds) are welded using TIG (Tungsten Inert Gas) welding or high-purity copper brazing (with phosphorus-free filler) to maintain the integrity of the stainless steel microstructure.
- Surface Finishing: Tubes undergo electropolishing and passivation treatments to remove surface contaminants, enhance corrosion resistance, and achieve a smooth surface finish (Ra ≤ 0.4 μm) that minimizes refrigerant flow resistance.
- Pressure Testing: Each coil tube assembly undergoes a 100% hydrostatic pressure test at 1.5 times the rated working pressure, held for a minimum of 30 minutes to verify leak-tightness.
- Final Inspection: Dimensional verification, visual inspection, and non-destructive testing (NDT) including dye penetrant testing are performed prior to packaging.
5. Applications
These stainless steel coil tubes are integral components in a wide range of HVAC systems, including:
- Commercial Fan Coil Units: Ceiling-mounted, wall-mounted, and concealed FCUs for office buildings, hotels, and hospitals.
- Residential Air Conditioning Systems: Ducted and ductless split-system indoor units.
- Industrial Process Cooling: Precision temperature control in semiconductor manufacturing, pharmaceutical cleanrooms, and food processing facilities.
- Marine HVAC Systems: Corrosion-resistant coil tubes for ships and offshore platforms where 316L grade provides essential chloride resistance.
- Heat Recovery Systems: Air-to-air and air-to-water heat exchangers in energy-efficient building management systems (BMS).
6. Quality Certifications and Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system and adheres to internationally recognized standards:
- ISO 9001:2015 — Quality Management System certification ensuring consistent product quality and customer satisfaction.
- ISO 14001:2015 — Environmental Management System certification for sustainable manufacturing practices.
- GB/T 19232 — Chinese national standard for Room Air Conditioner with Fan Coil Unit, governing performance, safety, and efficiency requirements.
- ASHRAE Standard 34 — Refrigeration and Air-Conditioning Safety Standard for refrigerant safety classification.
- EN 14511 — European standard for air conditioners, fluid-cooled heat pumps, and dehumidifiers.
- CE Marking — Conformity with European health, safety, and environmental protection standards.
- CNAS Accredited Testing — Product testing performed at China National Accreditation Service for Conformity Assessment laboratories.
7. Unique Selling Points
Exceptional Corrosion Resistance: Unlike traditional copper coil tubes, stainless steel coil tubes offer significantly extended service life (up to 25+ years) in corrosive environments, eliminating the need for frequent replacement and reducing total cost of ownership (TCO).
Superior Structural Integrity: High tensile strength and fatigue resistance ensure reliable performance under cyclic thermal and pressure loads, minimizing failure risk in continuous operation.
Hygienic Surface Finish: Electropolished surfaces prevent biofilm formation and bacterial growth, making these coil tubes ideal for healthcare and food-grade applications.
Environmental Sustainability: Stainless steel is 100% recyclable with no loss of material properties, aligning with global sustainability and circular economy objectives.
Custom Engineering Capability: Wenzhou Jixing Metal Materials Co., Ltd. offers fully customizable coil configurations — including tube diameter, pitch, row count, and header design — tailored to specific thermal load requirements.