Section 1: Product Overview

The SWF Mixed Flow Ventilation Fan represents a deliberate engineering response to the performance limitations of the two dominant conventional fan technologies — axial and centrifugal — in the mid-range building ventilation application space. The designation SWF identifies this as the mixed flow fan series developed by applying meridional acceleration and quasi-three-dimensional flow theory to produce a fan that fills the performance space between low-pressure axial fans and high-pressure centrifugal fans, precisely where the majority of building HVAC ductwork ventilation requirements fall.

What makes the SWF Mixed Flow Ventilation Fan commercially and technically significant is not that it is merely a compromise between two existing designs — it is that its meridional flow path design actively exploits the aerodynamic mechanisms of both axial and centrifugal flow simultaneously, achieving a combined performance point that is superior to what either conventional type can achieve at the same physical size. The practical outcome for the building systems designer is a fan that delivers the correct duty point at smaller physical dimensions, lower installed weight, simpler ductwork connections, and more economical energy consumption than the alternatives that would otherwise be required.

The advanced CAD multi-objective optimization process that underpins the SWF series design ensures that the impeller geometry is not simply a manually adjusted compromise but is mathematically derived to simultaneously maximize efficiency, pressure coefficient, and high-efficiency zone width — the three performance metrics that most directly affect the total cost of ownership of an installed fan over its service life. A fan with a narrow high-efficiency zone requires precise system resistance matching at design; a fan with a wide high-efficiency zone remains near-peak efficient across the natural variation in real building system resistance caused by filter loading, damper adjustments, and seasonal duct condition changes.

Dezhou Pengkai Air Conditioning Equipment Co., Ltd. is a comprehensive HVAC manufacturer based in Dezhou, Shandong Province, integrating research and development, production, sales, installation, and after-sales service. We supply SWF mixed flow ventilation fan products to HVAC system integrators, building contractors, mechanical and electrical consultants, and equipment distributors across Southeast Asia and global markets.

Section 2: Product Structure and Key Components

Streamlined Cylindrical or Drum Casing The fan casing is a cylindrical or drum-shaped housing fabricated from Q235 carbon steel with corrosion-resistant paint finish as the standard configuration. The casing profile is optimized for minimal external dimensions relative to the internal flow passage area, achieving the approximately 30 percent size reduction compared to centrifugal fans of equivalent airflow that is one of the key installation advantages of the SWF series. Standard inlet and outlet flanges at both ends allow direct connection to round ductwork without transition pieces. Optional inlet bell-mouth or streamlined inlet cone provides smooth flow guidance onto the impeller face. For installations requiring acoustic performance, a factory-assembled silencer section can be combined with the fan body to form a complete acoustic-attenuating ventilation unit.

Quasi-Three-Dimensional Impeller The impeller is the core aerodynamic component of the SWF Mixed Flow Ventilation Fan, embodying the quasi-three-dimensional flow design in its geometry. The conical hub form and twisted blade profiles are derived from meridional flow path analysis that specifies the velocity distribution through the impeller passage as a three-dimensional field rather than the series of independent two-dimensional cross-sections used in conventional fan design. Blades are fabricated from steel plate by hydraulic pressing to produce the specified three-dimensional profile, with blade-to-hub connections by welding. The hub is formed by hydraulic drawing processes that produce the required conical profile with dimensional accuracy. All completed impellers are dynamically balanced to G6.3 grade or better — a precision level that ensures smooth vibration-free operation across the full motor speed range from low-speed daily ventilation through high-speed emergency or maximum-load operation.

Internal Fixed Guide Vanes Fixed guide vanes are installed within the casing downstream of the impeller to redirect the rotational velocity component of the impeller exit flow into the axial direction, recovering this kinetic energy as additional static pressure and simultaneously suppressing the rotational turbulence that would otherwise generate significant noise in the downstream ductwork. The guide vane geometry is coordinated with the impeller blade exit angle to ensure effective flow redirection across the operating range. The internal guide vane assembly contributes both to the pressure performance and the acoustic performance of the SWF Mixed Flow Ventilation Fan relative to guide-vane-free mixed flow designs.

Direct-Drive Motor with External Terminal Box The motor is mounted co-axially within the airflow stream on the impeller shaft, using direct-drive without any belt, pulley, or coupling transmission. This configuration eliminates all transmission mechanical losses and maintenance requirements associated with these components. The motor is continuously cooled by airflow over its external surface throughout operation. All electrical connections are brought out to an external terminal box on the casing exterior, accessible for maintenance without fan disassembly or duct disconnection. Motor options span Y-series standard single-speed motors for fixed-duty applications, dual-speed motors providing high-speed and low-speed operating modes, variable frequency compatible motors for stepless 25 Hz to 50 Hz speed control, and explosion-proof motors for classified hazardous area applications.

Material Options Standard housing and impeller material is Q235 carbon steel with corrosion-resistant paint. For applications where exhaust air composition, installation environment humidity, or cleaning agent exposure would cause premature corrosion of steel construction, two alternative material options are available: stainless steel grades 304 or 316 for resistance to moderate chemical environments, food-grade cleaning agents, and coastal high-humidity conditions; and glass fiber reinforced plastic for resistance to more aggressive chemical fumes in industrial process exhaust applications. Sealing components in all material configurations use temperature-resistant, weather-resistant materials appropriate to the operating environment.

Section 3: Technical Specifications

Representative Performance Data:

Complete performance data for all machine numbers across all speed options available upon request. Contact our sales team with system airflow, static pressure, and installation requirements for model selection guidance.

Section 4: CAD Multi-Objective Optimization — The Design Advantage

The SWF Mixed Flow Ventilation Fan series was developed using advanced CAD multi-objective optimization methodology applied to the quasi-three-dimensional flow design framework. Understanding the significance of this design approach clarifies why the SWF series delivers measurably superior performance compared to conventionally designed mixed flow fans.

What Multi-Objective Optimization Means in Practice Conventional fan design involves the designer manually iterating through blade geometry parameters — chord length, twist angle, camber, solidity — seeking a geometry that provides acceptable performance on a prioritized list of objectives while not violating constraints on other objectives. This manual iteration process is limited by the designer's ability to simultaneously consider multiple interacting variables and typically terminates at a locally optimal geometry that may be far from the global optimum.

CAD multi-objective optimization replaces this manual iteration with a computational process that systematically evaluates thousands of candidate geometries across the full design parameter space, using aerodynamic performance models derived from quasi-three-dimensional flow theory to predict the performance of each candidate. The optimization algorithm drives the search toward geometries that simultaneously maximize all specified objectives — efficiency, pressure coefficient, high-efficiency zone width — rather than trading off one against another as manual design typically requires.

The Quasi-Three-Dimensional Flow Model The quasi-three-dimensional flow model used in SWF design divides the impeller flow field into coupled meridional and blade-to-blade flow solutions, capturing the three-dimensional flow features of the conical impeller geometry that are ignored by the two-dimensional design approaches used for conventional axial fans. This higher-fidelity flow model allows the optimization to drive the geometry toward configurations that exploit the three-dimensional flow field advantageously — configurations that a two-dimensional design approach would never identify because its flow model cannot represent them.

High-Efficiency Zone Width — The Practical Benefit The wide high-efficiency zone covering rated duty ±20 percent is the most directly valuable outcome of the multi-objective optimization for the Energy Saving Mixed Flow Blower in real building system applications. Building ventilation system resistance varies continuously from design conditions as filters load up, Dampers adjust, seasons change, and occupancy patterns vary. A fan with a narrow high-efficiency zone operates near peak efficiency only at exactly the design point and degrades rapidly as system resistance moves away from this point. The broad high-efficiency zone of the SWF series maintains near-peak efficiency across all of these real-world operating condition variations, consistently reducing energy consumption relative to conventionally designed fans over the complete installed service life.

Section 5: How It Works — Operating Principle and Flow Path

Bell-Mouth Inlet Flow Conditioning Incoming airflow is guided by the optional bell-mouth inlet component onto the impeller face with progressively accelerating velocity and minimal turbulence. Clean, uniform inlet flow is the prerequisite for the quasi-three-dimensional impeller geometry to operate as designed — irregular or turbulent inlet flow disrupts the meridional velocity distribution that the blade geometry assumes, reducing both efficiency and acoustic performance.

Meridional Acceleration Through the Impeller Air entering the rotating impeller at the hub inlet simultaneously experiences axial thrust from the blade lift forces acting along the axis direction, and radial acceleration from the centrifugal effect of the conical hub geometry. As the airstream travels along the meridional flow surface from hub inlet to blade tip outlet, the quasi-three-dimensionally optimized blade geometry maintains attached flow throughout this passage by controlling the velocity gradient along the meridional surface. Both the axial and centrifugal contributions to pressure rise are captured and converted to static pressure, producing the characteristic mixed flow performance combination of high volume at medium-to-high pressure.

Guide Vane Swirl Recovery Air exiting the impeller carries both axial velocity — the useful flow component — and rotational velocity imparted by the impeller blade forces. The internal fixed guide vanes redirect the rotational velocity component into the axial direction, recovering the associated kinetic energy as additional static pressure and eliminating the rotational turbulence that would otherwise generate noise in the downstream ductwork. This swirl recovery step is a significant contributor to both the pressure performance and the quiet operation of the SWF Mixed Flow Ventilation Fan compared to impeller-only designs without guide vanes.

Variable Speed Operation — 25 Hz to 50 Hz For variable frequency motor configurations, the fan speed can be continuously adjusted from 25 Hz to 50 Hz supply frequency, corresponding to approximately 50 to 100 percent of rated speed. Because fan airflow varies approximately proportionally to speed and fan pressure varies approximately with the square of speed, variable frequency control provides precise and highly energy-efficient airflow adjustment. Operating at 75 percent of rated speed (37.5 Hz) reduces energy consumption to approximately 42 percent of full-speed consumption while delivering 75 percent of the full-speed airflow — a dramatic energy saving that justifies the variable frequency investment for applications with variable ventilation requirements.

Section 6: Manufacturing Process and Quality Control

Dezhou Pengkai Air Conditioning Equipment Co., Ltd. applies rigorous quality management throughout SWF Mixed Flow Ventilation Fan production:

Material Incoming Inspection Q235 carbon steel, stainless steel, FRP materials, motor units, and sealing components are inspected against specification on receipt. Motor units for dual-speed and variable frequency configurations receive additional function testing before entering assembly. Material and component certification documents are retained for each production batch.

Impeller Blade Hydraulic Pressing Impeller blades are formed by hydraulic pressing using precision tooling that produces the specified three-dimensional twist profile consistently across production runs. The quasi-three-dimensional blade geometry requires forming accuracy beyond what conventional flat or simple-curve blade designs demand. Blade profile dimensional verification is performed after pressing and before hub assembly.

Hub Hydraulic Drawing The conical impeller hub is formed by hydraulic drawing processes that produce the required conical profile with dimensional accuracy. Hub geometry directly affects the meridional velocity distribution in the impeller passage and must be consistent with design specifications for the aerodynamic performance model to be valid.

Impeller Assembly and G6.3 Dynamic Balancing Blades are welded to the hub at the specified angular positions. After complete assembly, each impeller undergoes dynamic balance measurement and correction to G6.3 grade or better. Both transverse and longitudinal balance planes are addressed, ensuring balanced operation across the full axial length of the impeller assembly.

Casing and Guide Vane Assembly The casing cylinder is formed, welded, and fitted with inlet and outlet flanges to dimensional tolerances consistent with standard ductwork flange specifications. Guide vanes are installed within the downstream casing section at the specified angular positions and verified for positional accuracy after installation.

Motor Installation and Terminal Box Wiring Motors are installed, co-axial alignment is verified, and all electrical connections are made to the external terminal box. Insulation resistance, rated current draw, and for multi-speed models, all speed switching functions are verified before dispatch.

Final Running Test Every completed Quasi Three Dimensional Flow Duct Fan undergoes a full-speed running test in all configured speed modes, verifying smooth operation, correct current draw at each speed, acceptable vibration, and external terminal box accessibility.

Section 7: Product Features and Advantages

Higher Pressure Than Axial, Higher Flow Than Centrifugal The quasi-three-dimensional meridional acceleration design simultaneously delivers pressure output exceeding conventional axial fans of the same machine number and airflow output exceeding centrifugal fans of equivalent physical size, providing the correct performance at smaller dimensions and lower weight than either alternative.

30 Percent Smaller Than Centrifugal Equivalents The compact inline cylindrical housing is approximately 30 percent smaller in overall dimensions than a centrifugal fan delivering equivalent airflow, directly reducing space consumption in mechanical shafts, plant rooms, ceiling voids, and any constrained installation environment.

Broad ±20% High-Efficiency Zone The multi-objective optimized impeller geometry sustains near-peak efficiency across rated duty ±20 percent, ensuring the SWF Mixed Flow Ventilation Fan operates energy-efficiently across real building system resistance variations throughout the installed service life without requiring recalibration or fan replacement as system conditions evolve.

Variable Frequency Saves Over 30% Energy Variable frequency operation from 25 Hz to 50 Hz provides stepless airflow adjustment with energy consumption proportional to the cube of speed ratio. Operating at reduced speed for partial load conditions saves over 30 percent of full-speed energy consumption, making the Energy Saving Mixed Flow Blower the economically optimal choice for applications with variable ventilation demand profiles.

Comprehensive Variant Range Explosion-proof, corrosion-resistant stainless steel and FRP, acoustic silencer, and rooftop installation variants within the same product platform allow the SWF series to be specified across the full range of building application environments without requiring separate product lines for each application type.

Direct-Drive Reliability The direct motor-shaft impeller drive eliminates all belt, pulley, and coupling transmission components, removing their associated maintenance requirements, mechanical losses, and failure modes. The only wear items in the drivetrain are the motor bearings, requiring only periodic lubrication in service.

Flexible Installation in Any Orientation Horizontal, vertical, floor-mounted, wall-mounted, and suspended installation configurations are all supported within the standard product specification, providing layout flexibility for any building mechanical system design.

Section 8: Application Scenarios

Central HVAC Fresh Air and Supply Air Systems Central fresh air handling systems, air conditioning supply air distribution networks, and mechanical ventilation supply systems in commercial office buildings, hotels, shopping centers, and hospitals represent the primary application domain of the SWF Mixed Flow Ventilation Fan. The mid-range pressure and high-volume performance of the SWF series precisely matches the system resistance and airflow requirements of these central HVAC duct systems.

Building Pressurization and Smoke Prevention Stairwell pressurization systems, lobby ante-room smoke prevention systems, and corridor pressurization duct networks require fans delivering controlled static pressure at specified airflow rates. Variable frequency motor configurations of the Quasi Three Dimensional Flow Duct Fan allow precise airflow and pressure adjustment during commissioning and ongoing operation to maintain specified pressure differentials.

Underground Car Park Ventilation Underground parking structure ventilation systems require high-volume fans capable of overcoming duct system resistance while maintaining carbon monoxide dilution airflow rates. The dual-speed motor option provides low-speed daily ventilation and high-speed peak-demand or emergency ventilation from a single installed unit.

Industrial Process Ventilation Factory production area general ventilation, process exhaust systems, paint booth air supply and exhaust, and clean room pressurization systems require fans covering a wide range of duty points with material options appropriate to different exhaust media. Stainless steel and FRP configurations of the Energy Saving Mixed Flow Blower serve corrosive process exhaust applications that would cause premature degradation of standard carbon steel construction.

Cold Storage and Refrigerated Facility Ventilation Cold storage warehouse ventilation, refrigerated processing facility air handling, and frozen food distribution center climate management require fans capable of reliable operation at low ambient temperatures. The standard operating temperature range of -20°C to +45°C covers cold storage ventilation requirements without requiring special low-temperature motor specifications.

Human Defense Engineering Ventilation Human defense engineering — civil defense shelter ventilation systems — requires fans capable of switching between normal peacetime ventilation and wartime NBC-filtered ventilation modes. The dual-speed motor configuration of the SWF-II series provides the two-mode operation required for defense shelter ventilation applications.

Agricultural Greenhouse and Livestock Facility Ventilation Large greenhouse growing facilities, poultry house climate control systems, and livestock building ventilation require high-volume fans with sufficient static pressure for duct distribution systems. Larger machine number configurations of the SWF Mixed Flow Ventilation Fan cover the high-volume requirements of large agricultural facility buildings.

Data Center and Equipment Room Cooling Ventilation Server room and Data Center Cooling air supply systems, UPS room ventilation, and electrical switchroom forced ventilation require reliable, energy-efficient fans with consistent airflow delivery. Variable frequency motor configurations allow precise airflow matching to real-time cooling loads, reducing energy consumption during periods of reduced IT equipment loading.

Section 9: Customer Application Feedback

Our SWF mixed flow ventilation fan products have been supplied to HVAC, industrial, and institutional projects across Southeast Asia and international markets:

"We specified Pengkai SWF fans for the fresh air supply duct systems of a large hotel complex. The compact body size compared to centrifugal fans allowed us to reduce mechanical shaft cross-sections on multiple floors, which was a significant design constraint on this project. Commissioning airflow measurements were within specification and the variable frequency option allowed precise final adjustment." — Mechanical and Electrical Consultant, Southeast Asia

"For a hospital building pressurization system requiring precise airflow control for infection control pressure differentials, the Pengkai Quasi Three Dimensional Flow Duct Fan with variable frequency drive gave us the stable, adjustable performance we needed. The broad high-efficiency zone means performance has remained consistent as the system has settled in over the first twelve months of operation." — HVAC System Integrator, Regional Project

"We have standardized on Pengkai Energy Saving Mixed Flow Blower products for central ventilation systems across our commercial building portfolio. The energy performance over several years of operation has consistently met our expectations, and the after-sales support for maintenance guidance and replacement parts is reliable." — Building Facilities Management Company

Section 10: Installation Guidelines

Pre-Installation Checks Verify machine number, speed configuration, motor type, housing material, flange dimensions, and operating conditions against design documents before installation. Inspect casing, impeller, guide vanes, motor, and terminal box for transport damage. Rotate the impeller manually to confirm it turns freely without contact with the casing or guide vanes.

Mounting Base and Anti-Vibration Isolation For floor-mounted installations, install rubber or spring anti-vibration mounts between the unit base and the foundation surface. Anti-vibration mounts prevent fan operating vibration from transmitting into the building structure. For suspended installations, use anti-vibration hanger isolators rated for the unit weight. Verify that mounting structure load capacity is adequate with a suitable safety factor above the unit weight.

Ductwork Soft Connections Connect inlet and outlet ductwork using flexible soft connectors — typically 150mm to 200mm length fabric or rubber sleeve connectors. Soft connections prevent vibration transmission between the fan and duct system and accommodate minor positional misalignment at installation. Ductwork must be independently supported and must not apply bending stress or weight to the fan flange connections.

Electrical Connection and Rotation Verification All electrical connections are made at the external terminal box. Verify supply voltage and phase configuration. For three-phase motors, verify correct rotation direction before completing ductwork installation — rotation direction arrow is marked on the casing. For variable frequency drives, configure drive parameters per motor nameplate before initial start. Verify that variable frequency drive output frequency range matches the fan motor specification.

Space Requirements Maintain a minimum 300mm clearance around the unit on all sides for maintenance access to the motor, terminal box, and ductwork connections. Ensure the terminal box face has unobstructed access for electrical maintenance.

Post-Installation Commissioning Perform initial running test in all configured speed modes, monitoring for abnormal noise, vibration, or current draw. For variable frequency configurations, test operation across the full frequency range from 25 Hz to 50 Hz. Measure delivered airflow at design operating point and verify against system requirements.

Section 11: Maintenance Schedule

Monthly Inspection Listen for changes in operating noise or vibration during operation. Verify terminal box cover sealing is intact. For kitchen and process exhaust applications, inspect accessible impeller surfaces through the inlet for grease or contamination accumulation.

Quarterly Cleaning Clean impeller blades, casing interior, and guide vane surfaces of accumulated dust using soft brush or low-pressure compressed air with power isolated. For applications with contaminated exhaust streams, cleaning frequency should be increased based on observed accumulation rates.

Annual Inspection Check motor bearing condition by listening for unusual noise and measuring vibration levels. Verify all mounting fasteners remain tight. Check terminal box connections for tightness and signs of overheating. Inspect impeller blades for surface corrosion, erosion, or mechanical damage that could affect balance. For motors with grease nipples, apply specified grease per motor manufacturer recommendation annually.

Section 12: Packaging, Shipping, and Lead Time

Packaging Each SWF Mixed Flow Ventilation Fan unit is packaged in protective carton packaging for smaller machine numbers and wooden crate packaging for larger units, with foam padding and structural blocking appropriate to unit dimensions and weight. Export-grade packaging is standard for all international shipments.

Minimum Order Quantity We accept single-unit project orders and multi-unit supply contracts. Please contact our sales team to discuss specific machine numbers, speed configurations, and project requirements.

Lead Time Standard machine numbers in single-speed Q235 carbon steel configurations are available with short lead times from production scheduling. Stainless steel, FRP, dual-speed, variable frequency, explosion-proof, and rooftop configurations are produced to order with lead times confirmed at order placement.

Shipping We ship from Dezhou, Shandong Province. Sea freight, air freight, and international express courier options are available. FCL sea freight is recommended for multi-unit project orders. We work with established freight forwarding partners serving Southeast Asia, the Middle East, and global destinations.

Sample Policy Product samples for pre-order evaluation are available by arrangement. Sample costs and shipping fees are agreed prior to dispatch.

Payment Terms We support T/T bank transfer and other payment arrangements as mutually agreed. Please contact our sales team for terms appropriate to your order value and procurement process.

Section 13: Certifications and Quality Assurance

Dezhou Pengkai Air Conditioning Equipment Co., Ltd. manufactures SWF mixed flow ventilation fan products in compliance with applicable national standards for industrial and Commercial Ventilation equipment. Production quality management covers incoming material inspection, hydraulic-pressed blade profile verification, G6.3 dynamic balance testing of all impeller assemblies, guide vane installation verification, motor function testing, and completed unit running tests. Quality documentation for each production batch is available on request. Third-party pre-shipment inspection by buyer-nominated agencies is welcomed for project-specific orders.