Stainless Steel Coil Tube for ADAT-30 Cabinet Fan Coil Unit

Product Overview

The Stainless Steel Coil Tube (Model No. 920) is a precision-engineered serpentine heat exchange element designed for integration into the ADAT-30 Cabinet Fan Coil Unit (Cabinet-Fan Coil Unit). Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., this coil tube serves as the core thermal transfer component within the air-side heat exchange assembly. The coil tube is engineered to maximize surface-area-to-volume ratio, thereby enhancing convective and conductive heat exchange efficiency between the working fluid (water or refrigerant) and the ambient air stream within the fan coil housing.

This product belongs to the Documentary Learning (文献学习) category, indicating its role as a reference-grade component specification within the engineering documentation framework for ADAT-series fan coil systems.

Material & Properties

The coil tube is fabricated from high-grade stainless steel, selected for its superior corrosion resistance, mechanical strength, and long-term thermal stability under repeated heating and cooling cycles.

Specifications

Parameter Specification Unit
Product Designation ADAT-30 Coil Tube (盘管) —
Item Number (序号) 920 —
Tube Outer Diameter (OD) 9.52 mm (⅜")
Tube Wall Thickness 0.81 – 1.00 mm
Coil Pitch (Row Spacing) 15.0 – 20.0 mm
Number of Rows (排数) 2 – 4 —
Coil Length (Heat Exchange Surface) Adjustable per unit capacity m
Fins (if finned variant) Aluminum or stainless steel corrugated fins —
Fin Spacing 2.0 – 2.5 mm
Cooling Capacity (Typical) 3.0 – 3.5 kW
Heating Capacity (Typical) 3.0 – 3.5 kW
Flow Rate (Cooling) 0.6 – 0.7 L/s
Flow Rate (Heating) 0.4 – 0.5 L/s
Pressure Drop (at nominal flow) ≤ 15 kPa
Connection Type Threaded (G½" or 3/4") or flanged —
Refrigerant / Fluid Compatibility Hot water, chilled water, glycol-water mixture —

Manufacturing Process

The production of the ADAT-30 Coil Tube follows a rigorously controlled multi-stage manufacturing sequence to ensure dimensional accuracy, metallurgical integrity, and thermal performance:

  1. Material Selection & Incoming Inspection: Stainless steel seamless or welded tubes are procured per ASTM A213 / GB/T 14976 specifications. Each batch undergoes spectroscopic analysis (spectrometry) to verify chemical composition, mechanical testing for tensile strength and yield strength, and visual inspection for surface defects.
  2. Cutting & End Preparation: Tubes are precision-cut to specified lengths using automated sawing equipment. Ends are deburred, chamfered, and cleaned to prevent contamination during subsequent forming operations.
  3. Coiling / Serpentine Forming: Tubes are formed into the serpentine coil geometry using CNC-controlled bending machinery. Bend radii are maintained at a minimum of 3D (three times the tube diameter) to prevent wall thinning and ovality exceeding 1.5%. The forming process preserves the austenitic microstructure without introducing cold-work hardening that would compromise corrosion resistance.
  4. Fin Attachment (for finned variants): Aluminum or stainless steel corrugated fins are mechanically or brazed onto the coil tubes using a fin-coil rolling or brazing furnace process. Brazing is performed in a protective nitrogen atmosphere to prevent oxidation.
  5. Welding & Header Assembly: Individual coil passes are welded to inlet and outlet headers using TIG (Tungsten Inert Gas) welding with matching filler wire. Weld seams are inspected for continuity and penetration.
  6. Passivation & Surface Treatment: The assembled coil undergoes acid passivation (typically using a citric or nitric acid solution) to remove free iron and restore the chromium oxide passive layer, ensuring long-term corrosion protection.
  7. Hydrostatic Pressure Testing: Each coil assembly is subjected to a hydrostatic test at 1.5 times the maximum working pressure for a minimum dwell time of 30 minutes to verify leak-tightness and structural integrity.
  8. Final Inspection & Packaging: Completed units undergo dimensional verification, visual inspection, and are packaged with protective caps on all connection ports to prevent damage during transit.

Applications

The ADAT-30 Coil Tube is specifically engineered for the following applications within the HVAC (Heating, Ventilation, and Air Conditioning) industry:

Quality Certifications & Standards Compliance

Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring that every coil tube product meets or exceeds international and domestic standards:

Unique Selling Points

1. Superior Corrosion Resistance: The use of austenitic stainless steel (304/316L) provides exceptional resistance to condensate corrosion, a critical advantage over copper or carbon steel coils in humid environments. This extends the service life beyond 15 years under normal operating conditions.

2. Optimized Thermal Performance: The serpentine coil geometry is mathematically optimized for the ADAT-30 capacity range, achieving a balanced trade-off between heat transfer coefficient (U-value) and pressure drop, resulting in energy-efficient operation.

3. Precision Manufacturing: CNC-controlled bending and forming processes ensure consistent bend radii, tube alignment, and fin attachment quality, minimizing flow maldistribution and maximizing uniform heat exchange across the entire coil face.

4. Low Maintenance Design: The passivated stainless steel surface resists scale and fouling accumulation, reducing the frequency of chemical cleaning and descaling operations compared to conventional materials.

5. Full Traceability: Each coil tube batch carries complete traceability documentation including material mill certificates, heat numbers, test reports, and manufacturing records, enabling full lifecycle quality assurance.

Technical Notes & Installation Guidelines