Stainless Steel Coil Tube (Coiltube) — Concealed Fan Coil Unit Application
Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. (Product No. 1197) is a precision-engineered tubular component designed specifically for concealed fan coil unit (FCU) systems in modern HVAC (Heating, Ventilation, and Air Conditioning) installations. This coil tube serves as the core heat exchange element within concealed-mounted fan coil units, facilitating efficient thermal transfer between circulating refrigerant or hot water and the surrounding air stream.
The product has been developed in alignment with evolving industry standards governing concealed fan coil unit testing requirements, ensuring compliance with the latest regulatory frameworks for performance verification, thermal efficiency assessment, and operational safety. The coil tube is engineered to meet stringent demands placed by concealed installations, where accessibility for maintenance is limited and long-term reliability is paramount.
Material & Properties
The coil tube is fabricated from high-grade stainless steel, selected for its exceptional corrosion resistance, thermal conductivity, and mechanical durability in HVAC operating environments.
- Base Material: Austenitic stainless steel (e.g., SUS304 / AISI 304, SUS316 / AISI 316), providing resistance to chlorides, condensation, and microbial growth common in concealed ducted systems.
- Wall Thickness: Typically 0.3–0.6 mm, optimized for thermal transfer efficiency while maintaining structural integrity under operating pressures.
- Surface Treatment: Electropolished or passivated inner surface to minimize flow resistance and prevent biofilm accumulation in water-circulated systems.
- Operating Temperature Range: −20 °C to +120 °C, accommodating both heating and cooling duty cycles.
- Pressure Rating: Designed for working pressures up to 1.6 MPa (gauge), with hydrostatic test verification at 2.4 MPa.
- Corrosion Resistance: Superior resistance to condensation corrosion, scale formation, and chemical degradation from HVAC treatment additives.
Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Product Code | 1197 |
| Manufacturer | Wenzhou Jixing Metal Materials Co., Ltd. |
| Material Grade | SUS304 / SUS316 (Austenitic Stainless Steel) |
| Tube Outer Diameter (OD) | 6.35 mm / 9.53 mm / 12.7 mm (standard series) |
| Wall Thickness | 0.3 mm – 0.6 mm |
| Coil Diameter (Bundle) | Customizable (standard: 200 mm – 800 mm) |
| Fin Pitch | 2.0 – 2.5 mm (laminated aluminum or copper fins) |
| Operating Pressure | ≤ 1.6 MPa (gauge) |
| Hydrostatic Test Pressure | 2.4 MPa (gauge), 5-minute hold |
| Operating Temperature | −20 °C to +120 °C |
| Thermal Conductivity (Tube Material) | 16.3 W/(m·K) (SUS304) |
| Application Type | Concealed Fan Coil Unit (FCU) |
| Standards Compliance | GB/T, ISO 9001, relevant HVAC testing standards |
Manufacturing Process
The production of the stainless steel coil tube follows a rigorous multi-stage manufacturing protocol to ensure dimensional accuracy, material homogeneity, and functional reliability:
- Material Selection & Inspection: Raw stainless steel strip or tube stock is sourced from certified mills and subjected to spectroscopic analysis (OES) for compositional verification and visual inspection for surface defects.
- Tube Forming: Precision cold-rolling or drawing processes are employed to achieve the target outer diameter and wall thickness with tight tolerances (±0.05 mm).
- Coil Winding: The formed tube is mechanically wound into a serpentine or spiral coil pattern using CNC-controlled winding machinery to ensure uniform spacing and consistent geometry.
- Fin Attachment: Laminated aluminum or copper fins are inserted into the coil tube using a high-speed slitting machine, creating the extended surface area necessary for efficient air-side heat transfer.
- Hydrostatic Pressure Testing: Each coil assembly undergoes a 100% hydrostatic pressure test at 2.4 MPa for a minimum of 5 minutes to verify structural integrity and weld/bend quality.
- Surface Cleaning & Passivation: The coil is cleaned and chemically passivated to remove residual contaminants and enhance the protective chromium oxide layer.
- Final Quality Inspection: Dimensional verification, visual examination, and functional testing are performed in accordance with concealed FCU testing standards before packaging.
Applications
The stainless steel coil tube is primarily designed for use in concealed (ducted) fan coil units installed within suspended ceilings or wall cavities in commercial and residential buildings. Key application domains include:
- Commercial HVAC Systems: Office buildings, hotels, hospitals, and shopping malls requiring concealed cooling/heating distribution.
- Residential Climate Control: High-end residential units with integrated ducted HVAC systems.
- Cleanroom & Pharmaceutical Facilities: Environments demanding corrosion-resistant, non-shedding heat exchange components.
- Marine & Coastal Applications: Buildings in humid or salt-laden environments where standard carbon steel coils would be subject to accelerated corrosion.
- Food Processing & Hygiene-Critical Areas: Facilities requiring easily cleanable, non-reactive coil components.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system and adheres to recognized international and national standards:
- ISO 9001: Quality Management System certification ensuring consistent product quality and process control.
- GB/T Standards: Compliance with Chinese national standards for stainless steel tubes and HVAC components.
- Concealed FCU Testing Standards: Product performance verified against updated testing protocols governing concealed fan coil units, including thermal capacity measurement, airflow performance, and acoustic evaluation.
- Material Certification: Each production batch accompanied by mill test certificates (MTC) confirming chemical composition and mechanical properties.
- Hydrostatic Test Records: 100% pressure testing documentation retained for traceability and quality assurance.
Unique Selling Points
- Enhanced Corrosion Resistance: Stainless steel construction eliminates the risk of internal rust and scale buildup, extending service life significantly compared to carbon steel alternatives — critical for concealed installations where replacement is costly and disruptive.
- Standards-Aligned Performance: Engineered to meet the latest concealed FCU testing requirements, ensuring reliable performance verification and regulatory compliance.
- Long Service Life: Anticipated operational lifespan of 15–25 years without degradation of thermal performance or structural integrity.
- Hygienic Design: Smooth, passivated inner surfaces inhibit biofilm formation and reduce maintenance frequency in water-circulated systems.
- Customizable Geometry: Flexible coil dimensions and configurations to accommodate diverse concealed unit designs and installation constraints.
Note: The evolution of concealed fan coil unit testing standards places increasing demands on component-level quality, dimensional accuracy, and thermal performance consistency. This stainless steel coil tube product is engineered with these regulatory developments in mind, providing system integrators and OEMs with a reliable, standards-compliant heat exchange core component.