When ceiling plenums are too tight for standard rectangular fan boxes, DFS Series duct centrifugal fans provide high static pressure air movement in an ultra-low profile in-line casing.
Compare YONGFAN DFS-I series models (DFS-I-12 through DFS-I-37) across airflow (300 to 4,500 m³/h), total pressure (120 to 850 Pa), low sound ratings (≤45 to ≤65 dB(A)), and shallow depth ceiling void installations across commercial offices, hotels, and schools.
In modern commercial buildings, ceiling plenum heights are constrained by structural beams, electrical trays, and plumbing lines. Standard centrifugal scroll fans cannot physically fit into these spaces.
The DFS Series solves this spatial conflict by flattening the centrifugal volute into an in-line rectangular casing. Air enters axially and is accelerated through a double-inlet forward-curved impeller, generating static pressure up to 850 Pa in a fraction of standard cabinet height.
Sizing requires matching both available ceiling height and calculated duct static pressure.
Fits directly into shallow 250–400 mm ceiling plenums above false ceilings in hotels, offices, and residential towers.
Develops up to 850 Pa static pressure, easily overcoming resistance from multi-room extract grilles, silencers, and long flex ducts.
Integrated rectangular duct flanges on both inlet and discharge simplify connection without requiring complex offset transitions.
Covers 300 to 1,200 m³/h and 120 to 350 Pa. Ideal for hotel ensuite bathrooms, residential toilet extract, and small private meeting rooms.
Covers 1,200 to 2,800 m³/h and 250 to 550 Pa. Engineered for multi-room commercial office supply, school classrooms, and clinic ventilation.
Covers 2,500 to 3,800 m³/h and 350 to 700 Pa. Delivers higher static pressure for long multi-elbow duct runs and sound attenuator banks.
Reaches up to 4,500 m³/h and 850 Pa total pressure. The highest capacity unit in the DFS-I family for central branch collection.
| Model Code | Airflow Capacity (m³/h) | Static Pressure Range (Pa) | Speed (r/min) | Motor Power (kW) | Sound Level (dB(A)) | Action |
|---|---|---|---|---|---|---|
| DFS-I-12 | 300 – 850 m³/h | 120 – 280 Pa |
1,400 r/min | 0.08 kW | ≤ 45 dB(A) | Configure |
| DFS-I-15 | 600 – 1,350 m³/h | 150 – 350 Pa |
1,400 r/min | 0.12 kW | ≤ 48 dB(A) | Configure |
| DFS-I-20 | 1,100 – 2,100 m³/h | 200 – 450 Pa |
1,400 r/min | 0.25 kW | ≤ 52 dB(A) | Configure |
| DFS-I-22 | 1,400 – 2,500 m³/h | 220 – 500 Pa |
1,400 r/min | 0.37 kW | ≤ 55 dB(A) | Configure |
| DFS-I-25 | 1,800 – 2,900 m³/h | 250 – 580 Pa |
1,400 r/min | 0.55 kW | ≤ 58 dB(A) | Configure |
| DFS-I-28 | 2,200 – 3,400 m³/h | 280 – 650 Pa |
1,400 r/min | 0.75 kW | ≤ 60 dB(A) | Configure |
| DFS-I-30 | 2,600 – 3,900 m³/h | 300 – 720 Pa |
1,400 r/min | 1.10 kW | ≤ 62 dB(A) | Configure |
| DFS-I-37 | 3,200 – 4,500 m³/h | 350 – 850 Pa |
1,400 r/min | 1.50 kW | ≤ 65 dB(A) | Configure |
DFX fan boxes feature heavy double-skin insulated panels, providing superior casing breakout acoustic attenuation for high-spec mechanical rooms.
However, DFX cabinets are taller. When the ceiling void depth is less than 500 mm, DFS duct fans fit directly where DFX cabinets cannot physically be installed.
DFS provides up to 850 Pa static pressure for commercial distribution ducts. If the system involves extensive process equipment, industrial cyclone collectors, or multi-branch riser networks exceeding 1,000 to 3,000 Pa, the 4-72 industrial scroll fan is required.
Submitting your required airflow, calculated branch duct resistance, and available ceiling clearance allows our team to confirm model selection and provide dimensioned CAD submittals.
Casings are precision laser-cut and seam-locked from high-yield galvanized sheet steel, providing high rigidity and rust protection in humid ceiling spaces.
Double-inlet forward-curved centrifugal wheels are dynamically balanced to ISO 1940 G2.5, minimizing structure-borne ceiling vibration.
Motor and impeller core assembly unbolts from the bottom panel, allowing full maintenance without disconnecting adjacent ductwork.
Full electrical current, acoustic sound power, and bearing alignment undergo 100% factory verification prior to dispatch.
The DFS-I series covers 300 to 4,500 m³/h airflow and 120 to 850 Pa static pressure across models DFS-I-12 through DFS-I-37.
Choose DFS when ceiling void height is restricted (< 500 mm). DFS features an ultra-low profile in-line casing that fits directly into shallow plenums.
DFS features a bottom drop-out motor and wheel assembly. Technicians can service or replace the core motor from below without dismantling connected duct flanges.
DFS fans feature integrated rectangular duct flanges on both the inlet and discharge for direct bolting to standard rectangular galvanized ductwork.
Yes. DFS fans support multi-speed stepped switching (High/Med/Low) or continuous VFD frequency modulation depending on motor type.
Published noise ratings range from ≤45 dB(A) on smaller units (DFS-I-12) to ≤65 dB(A) on large units (DFS-I-37) at rated duty.
Standard DFS handles clean air up to 60 °C. For hot greasy kitchen exhaust, specify SJG Cabinet Fans or T35-11 Bifurcated Fans with external motors.
Yes. Models DFS-I-15 through DFS-I-22 are widely specified for multi-room hotel ensuite and commercial restroom extract headers.
Send your required airflow, calculated static pressure, available ceiling clearance, and acoustic limits — our application engineers will confirm the optimal DFS-I model and provide complete technical submittals.
