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Fire Smoke-Exhaust Fan Boxes | HTFC | YONGFAN
280 °C / 30 min Fire Duty · Dual-Speed Smoke Control

Fire Smoke-Exhaust Fan Boxes: HTFC Series for High-Temp Emergency Smoke Control

A smoke-exhaust fan box must deliver the required emergency airflow at elevated temperature while also matching normal ventilation, duct pressure, control logic and installation access.

YONGFAN documents the HTFC family from 1,400 to 171,000 m³/h, 190 to 1,460 Pa total pressure, with a 280 °C / 30 min smoke-exhaust rating. Available in HTFC-I single-speed and HTFC-II dual-speed configurations for stairwells, corridors, basements, car parks, and public assembly spaces.

Fire Rating280 °C / 30 min
Airflow Spectrum1,400 – 171,000 m³/h
Total Pressure190 – 1,460 Pa ΔPt
Speed DutyHTFC-I Single · HTFC-II Dual
Select a Fire Smoke-Exhaust Fan Box HTFC Specification Matrix
HTFC fire smoke-exhaust fan box installation in commercial equipment room
HTFC Fire Smoke-Exhaust Series 280 °C / 30 min Certified · HTFC-I Single & HTFC-II Dual Speed Cabinets
01 / Life-Safety Aerodynamics

Smoke-Exhaust Failures Begin When Normal Ventilation and Fire Duty Are Treated as the Same Operating Point

A fan box can perform correctly every day and still be wrong for the emergency condition that matters most.

During normal operation, the system may need moderate airflow for heat, odor or contaminant control. In a fire, the same duct network can require a much higher airflow to extract smoke and maintain the intended smoke-control path. If the fan is selected only for the normal duty, the emergency operating point may fall outside the required range.

The reverse mistake also occurs. A fan sized only for maximum fire airflow can be oversized for daily operation, creating unnecessary noise and energy use. That is one reason YONGFAN separates HTFC-I single-speed and HTFC-II dual-speed configurations.

The second failure is confusing a high-temperature fan rating with a complete smoke-control system approval. The fan box is only one component. Dampers, smoke ducts, power supply, controls, fire alarm interfaces and the system sequence all have to operate together. ISO 21927-3:2021 treats powered smoke and heat exhaust ventilators as components within a smoke-control system and defines product characteristics and assessment methods for this type of equipment.

The third failure is selecting from maximum airflow instead of the required airflow-pressure point. Smoke ducts, fire dampers, louvers, shafts and discharge fittings all add resistance. A fan that reaches the scheduled airflow only at a lower pressure will not necessarily deliver that airflow once connected to the real smoke-exhaust network.

Commercial high-rise smoke extraction and ventilation shaft network

HTFC therefore needs four inputs before model selection:
normal ventilation duty, emergency smoke duty, total system pressure and fire-temperature requirement.

YONGFAN documents the HTFC family from 1,400 to 171,000 m³/h, 190 to 1,460 Pa total pressure, with a 280 °C / 30 min smoke-exhaust rating.

1. Dual Operating Points

Normal ventilation and fire smoke exhaust have completely different flow-pressure demands. Sizing only for one duty risks failure in the other.

Dual Duty · HTFC-I vs HTFC-II

2. Complete System Loop

A 280 °C fan is one component. ISO 21927-3:2021 compliance requires smoke dampers, fire ducts, emergency power, and control logic to match.

ISO 21927-3:2021 · System Coordination

3. Real Network Pressure

Dampers, shafts, louvers, and duct fittings add heavy resistance. Fans must be sized to deliver scheduled CFM at actual installed total pressure.

Airflow-Pressure Point · 190–1,460 Pa
02 / Engineering Parameters

Fire Temperature, Airflow and Pressure Control Different Parts of the Specification

Understanding how each parameter impacts model selection, speed configuration, motor ratings, and physical envelope.
Parameter 01

Fire Temperature Duty

The 280 °C / 30 min rating describes the high-temperature emergency duty. YONGFAN states that the HTFC fan box can operate for 30 minutes at approximately 280 °C ambient during fire smoke exhaust.

That figure should not be interpreted as a normal continuous-air temperature.

280 °C / 30 min Emergency Duty
Parameter 02

Airflow Spectrum

The airflow requirement comes from the smoke-control design. YONGFAN’s documented HTFC-I family extends from approximately 1,400 to 171,000 m³/h.

1,400 – 171,000 m³/h Family Boundary
Parameter 03

Total Pressure Basis

The total pressure requirement comes from the resistance of the smoke-exhaust path. The published family range is approximately 190–1,460 Pa total pressure.

The pressure basis matters. If the project schedule uses static pressure, it should not be compared directly with a supplier’s total-pressure figure without reconciling the basis.

190 – 1,460 Pa Total Pressure
Parameter 04

Speed Configuration

The speed configuration determines whether one fan can serve one duty or two.

HTFC-I is single-speed.

HTFC-II is dual-speed. In the supplier’s table, the first three operating points for each model are the high-speed smoke-exhaust points and the last three are the lower-speed normal-ventilation points.

HTFC-I Single · HTFC-II Dual
Parameter 05

Motor Rating Pairing

The motor rating is tied to the selected duty. HTFC-II tables list high/low motor power as one pair because the motor supports both operating speeds.

Paired High / Low kW Motor Sizing
Parameter 06

Motor Location & Envelope

The motor location affects installation envelope and maintenance. YONGFAN states that motors of 7.5 kW or below can be top-mounted on request. Motors above 7.5 kW are side- or rear-mounted.

≤7.5 kW Top · >7.5 kW Side / Rear

Key Selection Rule: Moving from single-speed to dual-speed does not automatically increase fire capacity. It adds a second operating mode. Moving to a larger model can increase available airflow, but the selected pressure and motor must still match the emergency duty.

03 / Product Architecture

Single-Speed HTFC-I vs. Dual-Speed HTFC-II

Detailed technical comparison, published aerodynamic spectrums, and dual-speed operating point mapping.
Architecture 01 · Single-Speed Dedicated HTFC-I-10 to HTFC-I-40 · 1,400–171,000 m³/h

Choose HTFC-I when one operating speed is enough

The HTFC-I is the single-speed fire smoke-exhaust fan box.

It uses an external-motor arrangement with a double-inlet centrifugal fan. The product is intended for smoke-exhaust systems where one selected fan speed is sufficient for the required duty.

The documented HTFC-I range begins at HTFC-I-10 and extends through HTFC-I-40. Smaller HTFC-I-10 configurations cover approximately 1,400–6,300 m³/h depending on the selected motor and pressure point. Mid-range models extend substantially higher. HTFC-I-20 reaches roughly 6,900–30,900 m³/h across its published points. HTFC-I-25 reaches approximately 13,600–50,800 m³/h. At the upper end, HTFC-I-40 reaches approximately 171,000 m³/h, with published total-pressure points extending above 1,000 Pa on the larger configurations.

The family should not be sized from these endpoints. Each model has multiple airflow-pressure combinations and motor options. The buyer should select the row that matches the project operating point.

HTFC-I is the stronger choice when:
  • smoke exhaust is the main duty;
  • normal ventilation does not require a separate lower-speed operating point;
  • control simplicity is preferred;
  • the system already has another fan for ordinary ventilation;
  • the selected single-speed point fits both the pressure requirement and available electrical capacity.

If the same fan box must provide substantially lower airflow every day and then switch to a higher emergency airflow, HTFC-II is usually the more direct architecture.

Select HTFC-I Sizing View HTFC-I Data
HTFC-I single-speed fire smoke exhaust fan box fabrication
HTFC-I Single-Speed Series External Motor · Double-Inlet Wheel · 1,400 to 171,000 m³/h
Architecture 02 · Dual-Speed Combined HTFC-II-10 to HTFC-II-40 · Dual Operating Points

Choose HTFC-II when daily ventilation and fire mode share one fan box

The HTFC-II combines two defined fan speeds in one unit.

YONGFAN documents low speed for ordinary ventilation and high speed for fire smoke exhaust. That relationship is visible directly in the performance table.

HTFC-II-10 High-Speed Points (Fire) • 4,900 m³/h at 820 Pa
• 5,400 m³/h at 800 Pa
• 6,100 m³/h at 800 Pa
HTFC-II-10 Low-Speed Points (Vent) • 3,200 m³/h at 370 Pa
• 3,600 m³/h at 360 Pa
• 4,100 m³/h at 360 Pa

The high/low motor rating is 2.2/1.5 kW.

This is the core benefit of HTFC-II. The fan can operate at a lower day-to-day duty without forcing the building to run at the full emergency airflow.

Larger models follow the same concept:

  • HTFC-II-20: publishes high-speed duty up to approximately 31,300 m³/h and low-speed duty up to approximately 20,800 m³/h.
  • HTFC-II-30: reaches approximately 78,000 m³/h at high speed and approximately 58,800 m³/h at low speed.
  • HTFC-II-40: reaches approximately 132,500 m³/h at high speed and approximately 98,000 m³/h at low speed.

Those figures show why the two operating modes should be selected together. A model that satisfies the fire duty may not automatically provide the desired normal ventilation point at low speed.

The control design must also prevent incorrect simultaneous or transitional states. The electrical engineer should coordinate the dual-speed motor starter, fire-alarm signal, interlocks and emergency power arrangement with the smoke-control sequence.

Select HTFC-II Sizing View HTFC-II Data
HTFC-II dual speed smoke extraction cabinet in plant room
HTFC-II Dual-Speed Series Daily Low-Speed Ventilation + High-Speed 280 °C Fire Smoke Mode
Selection Methodology

Select the model from both normal and emergency duties

For HTFC-I, the selection problem is one operating point. For HTFC-II, it is two.

A useful HTFC-II selection can be written as:
Normal mode: airflow + total pressure
Fire mode: airflow + total pressure + 280 °C / 30 min

Both points should sit within the selected model’s documented high/low performance.

For example, choosing HTFC-II only because its high-speed airflow matches the fire schedule is incomplete. The low-speed point may deliver too much or too little daily ventilation. The opposite is also possible. A low-speed point may fit the everyday system perfectly while the corresponding high-speed point lacks the pressure required after all fire dampers and smoke-duct losses are included.

Do not assume that doubling airflow requires doubling motor power. Fan power changes with both airflow and pressure, and the supplier table should be used for the actual model.

For fire mode, pressure calculations should include the configuration expected during the emergency sequence: open smoke dampers, shaft losses, discharge louvers and any fire-mode duct route.

04 / Building Applications

Match HTFC Configuration to the Building Duty

Tailored engineering selection across high-rise hotels, commercial offices, public assembly spaces, and underground car parks.
High-Rise & Hotels

High-rise buildings and hotels

YONGFAN identifies HTFC-I-10 / HTFC-I-12 as starting points for stairwell, corridor and similar building smoke-exhaust duties.

The important question is whether the fan is dedicated to emergency use or also operates during normal occupancy.

A dedicated smoke-exhaust shaft may favor HTFC-I. A shared ventilation/smoke system may favor HTFC-II because the low-speed mode can serve ordinary ventilation while the high-speed mode is reserved for fire operation.

For high-rise projects, electrical resilience and smoke-zone control are often as important as the fan size. Confirm emergency power, control signal, damper sequence and the exact smoke zone served by each fan.

Stairwells · Pressurization · Zones
Commercial Buildings

Commercial buildings

The supplier recommends HTFC-II-12 / HTFC-II-15 for commercial buildings that combine daily ventilation with fire smoke extraction.

This is a typical dual-speed application. The lower speed reduces ordinary airflow and noise. The higher speed provides the emergency duty.

The trade-off is control complexity. A dual-speed fan requires a control scheme that correctly transfers from normal ventilation to fire mode. It should not depend on an ordinary comfort-control signal remaining active during the emergency sequence.

Dual-Speed · Low Sound · Controls
Malls & Assembly Halls

Malls and public assembly spaces

YONGFAN identifies HTFC-II-18 / HTFC-II-20 for larger retail and public assembly spaces.

These spaces can have substantial normal ventilation demand and much higher smoke-exhaust requirements.

The fire calculation should define the smoke reservoir or zone, design smoke layer, exhaust rate and make-up air strategy. HTFC is then selected against the resulting fan duty rather than from floor area alone.

Where multiple smoke zones share one fan, confirm which dampers open in each scenario and calculate the pressure for the actual active path.

Smoke Reservoirs · Make-Up Air
Car Parks & Basements

Car parks and basements

The source lists HTFC-I-15 / HTFC-I-18 for enclosed car parks and basement smoke extraction.

Car parks can also require normal CO-controlled ventilation, so a dual-speed HTFC-II may be relevant where the same fan serves both modes.

The project team should decide early whether normal ventilation is handled by the smoke-exhaust fan, separate ventilation fans or a jet-fan system.

That system-level choice determines whether HTFC-I or HTFC-II is more appropriate.

CO Ventilation · Jet-Fan System
05 / Specification Matrix

HTFC Specification Table

Complete parameter comparison between HTFC-I single-speed and HTFC-II dual-speed fire smoke-exhaust cabinet series.
Parameter HTFC-I HTFC-II
Primary role
 Single-speed smoke exhaust / selected ventilation duty Combined low-speed ventilation + high-speed smoke exhaust
Fire duty
280 °C / 30 min
280 °C / 30 min
Documented model range
HTFC-I-10 to HTFC-I-40
HTFC-II-10 to HTFC-II-40
Family airflow boundary
 1,400–171,000 m³/h across HTFC family High/low points defined by model
Family total-pressure boundary
 190–1,460 Pa across HTFC family High/low points defined by model
Motor arrangement
 External motor External dual-speed motor
Motor mounting
 Top option at ≤7.5 kW; side/rear above Same mounting rule
Casing
 Common corresponding HTFC casing Common corresponding HTFC casing
Explosion-proof route
 BHTFC-I available BHTFC-II available

The family endpoints above come from YONGFAN data. Final procurement should use the exact selected row, motor rating and confirmed drawing.

06 / Engineering Interchangeability

Supplier Changes Must Preserve Both Fire and Aerodynamic Performance

Replacing an HTFC fan box requires more than matching cabinet dimensions.
Checkpoint 01 / Ratings & Operating Points

Match Fire Temperature & High/Low Points

First match the fire-temperature rating.

A standard ventilation fan with the same airflow is not equivalent to a unit documented for 280 °C / 30 min.

Then match the aerodynamic point. Compare airflow and total pressure at the required operating condition.

For HTFC-II, compare both the high-speed and low-speed points. A replacement that matches high-speed fire duty but misses the normal low-speed duty is not functionally equivalent.

Aerodynamic curve and fire rated smoke damper interface
Checkpoint 02 / Electrical & Physical Fit

Motor, Controls & Mounting Clearances

Next compare the motor and control method. Confirm high/low motor ratings, starter arrangement and fire-mode switching logic.

Check motor location and service access. Top-, side- and rear-mounted motors change the equipment envelope. YONGFAN publishes separate outline tables for these arrangements.

Finally compare included accessories. Dampers, flexible connectors, vibration isolators and controls are documented as separate items. The fan-box supply should not be assumed to include the complete smoke-control package unless the contract says so.

Engineering submittals and electrical starter schematics
07 / Quality & Standards

HTFC Production and Fire-Duty Documentation

In-house sheet-metal forming, dynamic impeller balancing, performance testing, and export qualification.
In-House Forming

Profile & Panel Fabrication

YONGFAN states that HTFC fire smoke-exhaust fan boxes are produced in its own factory with in-house sheet-metal forming and assembly. The current source does not identify the factory location, so plant-specific qualification should be confirmed when required.

Aerodynamic Balance

Centrifugal Impellers & Balancing

The supplier documents profile and panel fabrication, assembly of double-inlet centrifugal impellers and dynamic balancing before final unit testing. Assembled HTFC units are checked for airflow, total pressure and noise against the selected data before release.

National Standards

JB/T 10281 & JB/T 10563

The source lists JB/T 10281-2014 for fire smoke-exhaust fans and documents the 280 °C / 30 min operating requirement. It also lists JB/T 10563-2006 for the base centrifugal fan.

Global Logistics

Export Packaging & Terms

For continuity of supply, YONGFAN lists on-site warehousing, export packaging and EXW, FOB, CIF and DDP delivery terms. Lead time is quoted according to quantity at the time of order.

International Standards Reference: For international projects, ISO 21927-3:2021 is a relevant powered smoke- and heat-exhaust ventilator standard, but YONGFAN’s retrieved source does not claim ISO 21927-3 certification. Request the exact market-specific certificate required by the project. Testing Disclosure: The source does not document a separate application laboratory. It does document fan performance testing and product release checks.
08 / Architectural Routing

HTFC is Not the Right Fire Product for Every Smoke-Control Architecture

Connecting system topology, tunnel thrust, hazardous ratings, and standard ventilation to the optimal equipment family.

Centrifugal Fire Smoke Fan Box

Use HTFC when the project needs a centrifugal fire smoke-exhaust fan box with an external motor and the selected airflow-pressure point fits the documented range.

HTFC-I / HTFC-II Series

In-Line Axial Smoke Exhaust

If the system requires a simple in-line axial smoke-exhaust fan, a fire-rated DTF configuration may fit the duct arrangement better.

DTF Axial Series

Tunnel Longitudinal Ventilation

If the project uses tunnel longitudinal ventilation, SDS/SDS(R) or another tunnel-specific fan should be selected from thrust and emergency ventilation strategy rather than HTFC duct pressure alone.

SDS / SDS(R) Jet Fans

Ordinary Continuous Ventilation

If the project needs only ordinary ventilation, standard DFX avoids specifying fire-duty equipment that the system does not require.

Standard DFX Cabinets

Hazardous Classified Atmosphere

If the installation is also a classified hazardous area, select BHTFC and verify the exact explosion-proof certificate in addition to the fire duty.

BHTFC Explosion-Proof

Final HTFC Approval Checklist

The final HTFC approval should connect fire temperature, emergency airflow, system pressure, control mode and motor arrangement in one confirmed configuration.

5-Point Approval Link
ALERTS — NOT PART OF THE PAGE. RESOLVE BEFORE PUBLISHING.
The HTFC source contains a note stating “Sizes DFX-I-18 and below preferentially use the external-rotor direct-drive structure.” This appears to be copied from DFX data and should not be used as an HTFC construction rule without confirmation.
Several HTFC-I performance-table motor entries appear anomalous relative to neighboring rows, including HTFC-I-30 at 30,000–35,400 m³/h and HTFC-I-34 at 31,000–60,200 m³/h. Verify the original table before publishing full model-level motor data.
The 280 °C / 30 min rating is supported by the supplied HTFC source, but market-specific certification numbers are not provided. Do not imply EN 12101-3, ISO 21927-3, UL or another third-party certification without the corresponding document.
BHTFC performance refers to HTFC-I / HTFC-II aerodynamic tables, but explosion-proof certification remains configuration-specific.
09 / Technical Q&A

Fire Smoke-Exhaust Fan Box FAQ

Direct engineering answers covering fire ratings, dual-speed operation, motor mounting, explosion-proof routes, and smoke system boundaries.

What fire duty does the YONGFAN HTFC fan box have?

The documented HTFC rating is approximately 280 °C for 30 minutes for fire smoke-exhaust operation.

What is the difference between HTFC-I and HTFC-II?

HTFC-I is single-speed. HTFC-II is dual-speed, using low speed for ordinary ventilation and high speed for emergency smoke exhaust.

Does HTFC-II use the same airflow in both modes?

No. Each HTFC-II model has separate high-speed and low-speed airflow-pressure points. Both operating modes must be checked during selection.

Which HTFC model has the largest documented airflow?

The HTFC-I-40 family entries reach approximately 171,000 m³/h. The largest HTFC-II high-speed entry in the supplied table reaches approximately 132,500 m³/h.

Can the motor be mounted on top?

YONGFAN states that an HTFC motor at 7.5 kW or below can be top-mounted on request. Larger motors are side- or rear-mounted.

Can HTFC be used for normal ventilation?

Yes. HTFC-II is specifically intended to combine low-speed daily ventilation with high-speed fire smoke exhaust. HTFC-I can also operate at its selected single speed where the system design calls for it.

Is an explosion-proof HTFC available?

Yes. BHTFC-I / BHTFC-II are the documented explosion-proof routes, with aerodynamic performance referenced to the corresponding HTFC tables.

Are dampers and controls included with HTFC?

The source states that dampers, flexible connectors, vibration isolators and controls are supplied separately unless otherwise specified.

Does the 280 °C / 30 min rating certify the whole smoke-control system?

No. It is the documented HTFC fan-box fire duty. Smoke ducts, dampers, controls, emergency power and the complete system sequence require their own project compliance.

10 / Sizing Checklist

What Operating Data Is Required for HTFC Sizing?

Essential parameters to confirm before finalizing single-speed HTFC-I or dual-speed HTFC-II models.
Engineering Sizing Checklist

Key Inputs for HTFC Selection

Submitting your required normal and fire airflows, calculated total duct pressure loss, and electrical starter parameters enables our team to confirm model sizing and supply certified 3D CAD/BIM drawings.

1. Normal Mode Airflow (m³/h / CFM)
2. Normal Mode Total Pressure (Pa ΔPt)
3. Emergency Fire Airflow (m³/h / CFM)
4. Emergency Fire Total Pressure (Pa ΔPt)
5. High-Temp Rating: 280 °C / 30 min Verified
6. Speed Mode: HTFC-I (Single) vs HTFC-II (Dual)
7. Motor Mounting: Top (≤7.5 kW) vs Side/Rear
8. Power Supply (380V / 3-Phase / 50Hz)
9. Explosion-Proof Route: BHTFC (GB 3836 Ex)
10. Fire Damper & Interlock Starter Sequencing
11 / Application Engineering Handoff

Select a Fire Smoke-Exhaust Fan Box

Connect fire temperature, emergency airflow, total system pressure, control mode, and motor arrangement into one confirmed configuration. Send your project schedule or drawings to our application engineers.

280 °C / 30 min Fire Duty Airflow (1,400 – 171,000 m³/h) Total Pressure (190 – 1,460 Pa) HTFC-I Single-Speed HTFC-II Dual-Speed Top / Side / Rear Motor Mount BHTFC Explosion-Proof Option
Select a Fire Smoke-Exhaust Fan Box Go to Selection Center Ask an HVAC Engineer
YONGFAN application engineers reviewing HTFC fire smoke-exhaust submittals
Direct Technical Selection Support
Fire temperature ratings, airflow-pressure points, 3D BIM models & submittals.
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