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Centrifugal Fans | 4-72 & SJG | YONGFAN
High Static Pressure · Scroll & Cabinet

Centrifugal Fans: High Static Pressure & Flexible Plant-Room Routing

Centrifugal fans are selected when the duct system needs more pressure, more flexible discharge routing, or a cabinet arrangement that an in-line axial or mixed-flow fan cannot provide.

Compare YONGFAN 4-72 industrial scroll fans and SJG cabinet-type centrifugal fans across airflow (380 to 46,988 m³/h), pressure (up to 3,200 Pa total · 820 Pa static), direct/belt drives, operating efficiencies (75–87%), and adjustable 0° to −90° discharge angles.

2 Key Series 4-72 Scroll · SJG Cabinet
Airflow Range 380 – 46,988 m³/h
Pressure Range 372–3,200 Pa Total · 65–820 Pa Static
Efficiency & Angle 75–87% · 0° to −90° Discharge
Choose a Centrifugal Fan Review Selection Principles
Industrial centrifugal scroll fan installation with high static pressure capability
Centrifugal Aerodynamics Heavy-Duty Scroll Casings · 75–87% Operating Point Efficiency
01 / Engineering Foundation

Centrifugal Fan Selection Starts with the Right Pressure Basis

A fan can look correctly sized because its maximum airflow exceeds the project requirement, yet still fail to deliver the scheduled volume after it is connected to the real duct system.

The reason is usually pressure. Filters, coils, silencers, long ducts, elbows, dampers and terminal devices all add resistance. The fan must generate enough pressure at the required airflow to overcome that resistance. If the selected operating point sits too close to the edge of the fan curve, a modest increase in system resistance can reduce airflow or force the fan to run inefficiently.

Centrifugal fans are chosen precisely because they can develop more pressure than an axial fan. YONGFAN’s centrifugal portfolio covers two distinct solutions: the heavy-duty 4-72 Scroll Fan for high total pressure (up to 3,200 Pa) and the SJG Cabinet Fan with external motor and adjustable discharge for constrained mechanical rooms.

Keep the pressure basis consistent: 4-72 publishes total pressure (ΔPt) while SJG publishes static pressure (ΔPs). Preserving the stated basis avoids costly sizing errors.

Centrifugal duct connection and pressure testing
Laboratory ratings (ISO 5801) vs. installed system effect.

High Static Head Delivery

Generates up to 3,200 Pa total pressure in 4-72 series, overcoming dense multi-stage filters, coils, and extensive industrial duct networks.

Capability: 372–3,200 Pa Total Pressure

High Aerodynamic Efficiency

Published efficiency reaches 75% to 87% around central operating points (points 3–6), maximizing CFM delivered per electrical kW.

Efficiency: 75%–87% at preferred points

Adjustable Discharge Routing

SJG cabinet allows 10° step discharge rotation from 0° to -90°, simplifying duct connections in cramped plant rooms and service spaces.

Flexibility: 0° to −90° rotatable outlet

Direct & Belt Drive Options

4-72 offers direct drive on smaller frames for low maintenance, and belt drive on larger units for precise speed and airflow matching.

Configuration: Direct & Belt Drive

Centrifugal Fan Selection Protocol

Balance airflow, pressure basis, plant-room footprint and airstream conditions to specify the compliant fan.

01 4-72: Heavy Scroll & High Total ΔP
02 SJG: Cabinet & External Motor
03 Pressure Basis: Total vs. Static
04 Central Curve Sizing (Points 3–6)
02 / Technical Metrics

Airflow, Pressure & Efficiency Answer Different Questions

Airflow defines volume, pressure defines resistance overcoming capability, efficiency defines electrical power demand, and drive defines maintenance.
Spectrum 01 / 4-72 Series

4-72 Scroll Fan Scope

1,131 to 46,988 m³/h airflow and 372 to 3,200 Pa total pressure across Ø280 to Ø800 mm diameters (No.2.8A–No.8A). Motors range from 0.67 to 41.96 kW with 75–87% operating point efficiency.

Spectrum 02 / SJG Cabinet

SJG Cabinet Fan Scope

380 to 15,070 m³/h airflow and 65 to 820 Pa static pressure across Ø285 to Ø1136 mm diameters. Motor sits outside the airstream (0.04 to 5.5 kW, IP44) with sound levels from ≤56 to ≤82 dB(A).

Spectrum 03 / Taxonomy Boundary

DFS Duct Centrifugal Note

DFS Casing-less Duct Centrifugal Fan (1,300–46,965 m³/h, 140–940 Pa) belongs under the Fan Boxes equipment structure rather than this standalone scroll category.

Published Pressure Comparison by Product Architecture

Preserve the stated pressure metric (ΔPt vs ΔPs) when comparing models.

Centrifugal Performance Baselines
4-72 Industrial Scroll Fan
372 – 3,200 Pa Total
1,131–46,988 m³/h · Direct/Belt · 75–87% Efficiency
SJG Cabinet-Type Centrifugal
65 – 820 Pa Static
380–15,070 m³/h · External Motor · 0° to −90° Rotation
1. Design Airflow m³/h required capacity
2. Pressure & Basis Total (ΔPt) vs. Static (ΔPs)
3. Architecture Scroll (4-72) vs Cabinet (SJG)
4. Drive & Discharge Direct/Belt & Outlet Angle
03 / Product Lineup

Choose the Centrifugal Family by Pressure and Packaging

Detailed engineering review of 4-72 scroll fans and SJG cabinet-type centrifugal fans.
Family 01 · 4-72 Series Scroll Casing · Up to 3,200 Pa

4-72 Series Centrifugal Scroll Fan

The 4-72 Series Centrifugal Fan is the primary YONGFAN general-purpose centrifugal fan for systems requiring substantial pressure capability across HVAC and industrial plants.

Published performance spans 1,131 to 46,988 m³/h and 372 to 3,200 Pa total pressure with impeller diameters from Ø280 to Ø800 mm (No.2.8A to No.8A). Built with a welded steel scroll casing, streamlined inlet cone and dynamically balanced backward-curved impeller, it achieves 75–87% efficiency near preferred central operating points (points 3–6 of 8 published points).

Airflow & Total Pressure
1,131 – 46,988 m³/h · 372 – 3,200 Pa
Efficiency Profile
75% – 87% at preferred points 3–6
Drive Types
Direct drive (small) · Belt drive (large)
Motor Specification
0.67 – 41.96 kW (IP44, Class B/F, 380V)
Curve Selection Note: Select 4-72 near operating points 3–6. Larger sizes beyond No.8A use aerodynamic similarity parameters; specific submittal curves should be confirmed for large frames.
View 4-72 Product Details Request 4-72 Sizing
4-72 Standard Size Scope
4-72 No.2.8A ~ 3.55A Ø280 – Ø355 mm 1,131 – 4,800 m³/h
4-72 No.4.0A ~ 5.0A Ø400 – Ø500 mm 3,500 – 12,500 m³/h
4-72 No.6.0A ~ 7.0A Ø600 – Ø700 mm 8,000 – 28,000 m³/h
4-72 No.8.0A Ø800 mm 16,000 – 46,988 m³/h

*Direct drive on smaller units; belt drive on larger frames.

Family 02 · SJG Series Cabinet Centrifugal · External Motor

SJG Series Cabinet-Type Centrifugal Fan

The SJG Series Cabinet-Type Centrifugal Ventilation Fan solves plant-room space constraints and handled-air contamination issues. Its motor is mounted outside the main airstream, while the centrifugal wheel and scroll are housed inside a protective cabinet.

Published performance spans 380 to 15,070 m³/h and 65 to 820 Pa static pressure with diameters from Ø285 to Ø1136 mm. The outlet discharge can be rotated in 10° steps from 0° to −90°, allowing clean duct alignment in tight service spaces. It is suited for kitchen and laboratory exhaust, hotels, basements, and mildly corrosive process areas.

Airflow & Static Pressure
380 – 15,070 m³/h · 65 – 820 Pa Static
Motor Location
External to airstream (0.04 – 5.5 kW)
Discharge Orientation
0° to −90° in 10° increments
Acoustic Range
≤56 – ≤82 dB(A) sound level
Mildly Corrosive Boundary: While external motor mounting protects electrical components from grease and moisture, severe chemical or explosive gas requires dedicated materials or Ex-rated builds.
View SJG Product Details Request SJG Sizing
SJG Standard Model Scope
SJG-No.2.5 ~ 3.5 Ø285 – Ø400 mm 380 – 2,800 m³/h
SJG-No.4.0 ~ 5.5 Ø450 – Ø600 mm 2,200 – 6,500 m³/h
SJG-No.6.0 ~ 8.0 Ø700 – Ø900 mm 5,500 – 11,500 m³/h
SJG-No.9.0 ~ 10 Ø1000 – Ø1136 mm 9,000 – 15,070 m³/h

*Discharge rotatable in 10° steps from 0° to -90°.

04 / Selection Matrix

Centrifugal Fan Family Routing & Comparison Table

Cross-reference YONGFAN 4-72 and SJG centrifugal fan families by application scope, published capabilities, and first input to confirm.
Product Family What It Solves Published Capability First Input to Confirm Specification Action
4-72 Series Centrifugal Fan Up to 3,200 Pa
General HVAC and industrial systems requiring stronger pressure capability
1,131–46,988 m³/h · 372–3,200 Pa Total · ≈75–87% Efficiency
 Required airflow and total pressure (ΔPt) Configure 4-72
SJG Cabinet-Type Centrifugal Rotatable Outlet
Cabinet exhaust with motor outside airstream and flexible discharge direction
380–15,070 m³/h · 65–820 Pa Static · Outlet 0° to −90°
 Required airflow, static pressure (ΔPs), airstream condition and outlet angle Configure SJG
Rule 01

Total vs. Static Head

4-72 publishes total pressure for industrial duct runs. SJG publishes static pressure for cabinet plant-room exhaust.

Rule 02

4-72 vs. SJG Selection

Choose 4-72 when pressure exceeds 820 Pa or flow exceeds 15,000 m³/h. Choose SJG for cabinet enclosure and motor isolation.

Rule 03

Centrifugal vs. Mixed-Flow

Mixed-flow provides in-line packaging up to 1,314 Pa. Centrifugal scroll architecture provides higher pressure capability up to 3,200 Pa.

Rule 04

Inlet & Outlet Conditions

Avoid abrupt elbows immediately at inlet/outlet to prevent system effect losses (ISO/TR 16219) from degrading catalog performance.

05 / Procurement Protocol

Project Data Required for Centrifugal Fan Selection

Provide design airflow, pressure basis, airstream condition and plant-room orientation before requesting fan sizing.
STEP 01

Airflow & Pressure Basis

Specify design airflow (m³/h) and state whether calculated pressure is total (ΔPt) or static (ΔPs) in Pa.

STEP 02

Airstream & Moisture

Identify air temperature, humidity, grease, dust or mildly corrosive gases to confirm casing and motor suitability.

STEP 03

Footprint & Discharge Angle

Provide available mechanical room footprint, inlet/outlet dimensions and required discharge rotation (0° to −90°).

STEP 04

Drive & Electrical Supply

Confirm direct drive vs. belt drive preference, 380V/50Hz supply, acoustic limits and any VFD control requirement.

Engineering Checklist

12 Parameters for Centrifugal Fan Selection

Send your available project data. YONGFAN application engineers will verify operating curve points, motor power margins and submittal drawings.

1. Design Airflow (m³/h or CFM)
2. Total or Static Pressure (Pa)
3. System-Resistance Calculation
4. Operating Air Temperature (°C)
5. Gas, Moisture, Grease or Dust Content
6. Fan Location (Plant room, duct, roof)
7. Inlet & Outlet Connections
8. Available Footprint Limits
9. Power Supply (380 V / 50 Hz 3-Phase)
10. Noise Limit Requirement (dB(A))
11. Drive Preference (Direct vs. Belt)
12. Outlet Direction (0° to −90° for SJG)
06 / Manufacturing Consistency

YONGFAN Centrifugal Fan Production & Quality Controls

Welded scroll fabrication, backward-curved impeller casting, dynamic balancing, and full duty run-testing ensure delivered hardware matches rated fan curves.
Precision Fabrication

Impeller Dynamic Balancing

Centrifugal impellers undergo dynamic balancing before final casing assembly, preventing bearing wear, shaft vibration, and housing stress.

Aerodynamic Run-Testing

Full Duty Point Checks

Completed fans are run-tested against rated operating duty, verifying airflow, total/static pressure, motor current draw, rotation and sound levels.

ISO 5801 Standard

Calibrated Performance Test

Aerodynamic verification references standardized airways. Casing weld integrity, inlet cone clearance and motor insulation are 100% verified.

Traceability

100% Inspection & Submittals

Final inspection covers casing paintwork, flange alignment, wiring, fasteners and packaging. Serial-number tracking and submittal curves are provided.

Bespoke Project Engineering: Performance curves, dimensioned drawings, custom discharge orientation, and special motor builds provided upon request. Configured Dispatch: Lead times quoted based on model, frame size, motor build, quantity and project specifications.
07 / Engineering Knowledge

Centrifugal Fans Frequently Asked Questions

Direct technical answers regarding pressure differences, drive selection, kitchen/lab exhaust applications, and DFS categorization.

Which YONGFAN centrifugal fan has the higher pressure range?

The 4-72 Series has the higher published pressure envelope at 372–3,200 Pa total pressure. SJG publishes 65–820 Pa static pressure, so the two values should be evaluated on their stated pressure basis.

Which centrifugal fan has the larger airflow range?

4-72 reaches 46,988 m³/h in the documented family range (No.2.8A–No.8A). SJG reaches 15,070 m³/h.

What efficiency is published for 4-72?

YONGFAN publishes approximately 75–87% near the preferred operating region and recommends selecting around operating points 3–6 of the eight listed points per model.

Is the 4-72 direct drive or belt drive?

Smaller 4-72 units are direct drive for low maintenance, while larger units are belt drive for speed adjustment flexibility.

When should I choose SJG instead of 4-72?

Choose SJG when the required duty falls inside its pressure range (≤820 Pa) and the project benefits from a cabinet body, motor-out-of-airstream construction or adjustable outlet direction (0° to −90°).

How much can the SJG outlet be rotated?

The documented outlet range is 0° to −90° in 10° increments, simplifying duct connections in cramped mechanical rooms.

Can SJG handle kitchen or laboratory exhaust?

Yes. The external motor arrangement keeps the motor out of the greasy or humid air. Final material suitability should still be verified against chemicals and grease loading.

Can 4-72 handle hot or corrosive air?

Special materials, coatings or stainless-steel construction can be supplied for elevated-temperature or mildly corrosive duties upon project review.

Is DFS included in the Centrifugal Fans category?

No. DFS Casing-less Duct Centrifugal Fan is part of YONGFAN’s Fan Boxes / Duct Centrifugal Fans structure because it is supplied as a casing-less unit inside a framed duct equipment concept.

08 / Application Boundaries

Centrifugal Fans Do Not Replace Every Architecture

Use a centrifugal fan because the system needs its pressure, discharge geometry or cabinet arrangement.
Boundary 01 / Low Resistance

Straight-Through Axial

If the system is high-flow and relatively low-resistance with a straight duct path, a DTF Axial Fan requires far less space.

Boundary 02 / In-Line Moderate ΔP

Mixed-Flow In-Line

If the system needs moderate pressure (≤1,314 Pa) but an in-line body is critical, SWF or CDZ Mixed-Flow Fans fit better.

Boundary 03 / Rooftop Exhaust

Roof-Specific DWT Series

If the fan must sit directly on the roof deck, use the dedicated DWT Roof Fans category rather than adapting an indoor 4-72 fan.

Boundary 04 / Packaged Duct Box

DFS Duct Centrifugal

If the project needs a packaged casing-less duct centrifugal fan inside a framed cabinet, review DFS Duct Centrifugal Fan under Fan Boxes.

09 / Engineering Handoff

Select the Right Centrifugal Fan for Your Facility

You do not need to calculate the fan curve alone. Send your design airflow, calculated total or static pressure, air conditions and plant-room drawings — our application engineers will confirm the optimal operating point and provide complete technical submittals.

Design Airflow (m³/h / CFM) Total Pressure (ΔPt) vs. Static (ΔPs) 4-72 Scroll vs. SJG Cabinet Direct Drive vs. Belt Drive Outlet Rotation (0° to −90°) Air Temperature & Composition 380 V / 50 Hz 3-Phase
Request a Centrifugal Fan Quote Go to Selection Center Contact Technical Support
HVAC application engineers reviewing centrifugal fan schedules
Direct Application Engineering Support
Duty-matched fan curves, pressure loss calculations, discharge orientation & CAD drawings.
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