Quick Answer

The 4-72A centrifugal fan is an A-type direct-drive ventilator: the impeller sits on the motor shaft, with no belts and no coupling. Benefits: highest transmission efficiency, compact layout, low vibration, minimal drive maintenance. It handles non-flammable, non-toxic, non-corrosive gases up to 80°C with dust not exceeding 150 mg/m³.

What Is the 4-72A Centrifugal Fan?

In the 4-72 code, "4" is the pressure coefficient and "72" the specific speed — moderate total pressure, high airflow. The suffix defines the drive: A = direct, impeller on the motor shaft; C = belt drive, motor outside the casing; D = coupling drive for larger sizes.

The 4-72A uses a backward-inclined impeller; the catalogue cites stable running, low vibration, high efficiency and long service life. Medium limits: no sticky substances, dust not above 150 mg/m³, temperature not above 80°C. Duties cover ventilation and exhaust in plants, large buildings, hotels and restaurants, and companion service on dust collectors, dryers and air handling units.

Key Advantages

No transmission losses

No belts or couplings: shaft power goes straight to the impeller. No slip, no transmission loss, and belt tensioning, replacement and alignment leave the maintenance plan.

Compact footprint

Impeller and motor share one shaft, so the unit is shorter and lighter than a belt-driven equivalent — easier in tight plant rooms and cheaper to base.

Low vibration, stable running

A short drive train leaves less room for unbalance and misalignment, so there is less fatigue on bearings, casing and ductwork and longer life overall.

Size and pole choice

Sizes 2.8A–7.4A, each with 2-pole, 4-pole or 6-pole motors. Two-pole gives more airflow and pressure; 4-pole and 6-pole run slower and quieter, so you avoid oversizing.

Minimal maintenance

Routine work is bearing lubrication, fastener checks and impeller cleaning — no belt inspection, no tensioning, no re-alignment, fewer planned stoppages.

Technical Parameters

Typical Applications

General ventilation in industrial plants

Process heat, welding fume and equipment losses need continuous removal. Several sizes sit in the 500–2000 Pa band, so a full system can be built with standard ductwork; dust up to 150 mg/m³ needs no pre-treatment.

Daily supply and exhaust in large buildings

Offices, shopping centres, car parks and equipment rooms need reliable daily air change, often in tight plant rooms. The compact layout suits wall or suspended mounting, and low vibration limits structure-borne noise.

Hotels, restaurants and public buildings

Guest rooms, banquet halls, kitchen make-up air and washroom exhaust are ambient-temperature, low-dust duties inside the 4-72A envelope. Use a 4-pole or 6-pole motor where noise matters.

Process air, drying and cooling

Drying and cooling sections in grain, feed, plastics and paper lines need a stable air stream. With no sticky substances, the fan works as supply or induced draught; collect upstream where dust is heavier. The layout also suits OEM builders of collectors and air handling units.

How to Select a 4-72A Centrifugal Fan

Confirm the following before requesting a quotation:

• Airflow (m³/h) — from air changes per hour or process demand, including diversity.

• Total pressure (Pa) — duct friction plus local losses plus equipment resistance, with margin.

• Medium temperature — rated up to 80°C; hotter duties need another design.

• Dust — not above 150 mg/m³; collect upstream if higher.

• Gas composition — non-flammable, non-toxic, non-corrosive to steel, no sticky substances; oil or paint mist duties are unsuitable.

• Motor poles — 2-pole for maximum airflow and pressure; 4-pole or 6-pole for lower noise.

• Power supply — motors for 220/380 V at 50/60 Hz; state the destination grid when ordering.

• Installation — plant room dimensions, foundation, inlet and outlet orientation, duct routing.

• Noise limits — state the required value at enquiry so a low-speed build can be checked.

Without a resistance calculation, send the duty description and we will estimate airflow and pressure.

Comparison: A-Type Direct Drive vs. C-Type Belt Drive vs. D-Type Coupling Drive

Fixed duty, moderate size — 4-72A. Duty likely to change, or airflow and pressure reset on site — 4-72C. Large size, high power — D-type. Above the 4-72 pressure range, use the 9-19 or 9-26 high-pressure ventilators.

Installation and Maintenance

Before installation. Check all parts are present, impeller rotation matches the casing arrow, connections are tight, and impeller, shaft and bearings are undamaged and turn freely.

During installation. Leave no tools or debris in the casing; coat joint faces with grease or machine oil against corrosion. Ducts must meet the fan naturally, never forced, and their weight must not bear on fan parts. Keep the shaft level.

Commissioning. Bar the fan over, close the damper or inlet control, start under no load, then open gradually and run at rated pressure and airflow. A new fan runs at least 2 hours, half an hour after overhaul, with current within the motor rating.

Operating limits. Bearing temperature rise must not exceed 40°C above ambient and surface temperature must not exceed 70°C; vibration velocity (RMS) must not exceed 4.5 mm/s. Severe vibration, knocking or fast temperature rise means stop and investigate.

Specific to the 4-72A. Concentricity is factory-set, so ensure a level foundation, tight anchors and flexible duct connections; after a long shutdown, bar over and jog the motor.

Why Choose Zhejiang Zifeng Fan Co., Ltd.

Based in Xiayuanshan Industrial Zone, Daxi Town, Wenling City, Zhejiang Province, Zhejiang Zifeng Fan Co., Ltd. combines research, development, design, manufacturing, installation and commissioning in one organisation.

• Certifications — ISO9001:2015 quality management system; CE conformity for EU export; explosion-proof certificate; third-party inspection reports.

• Scale — 200,000 m² of facilities, RMB 10 million registered capital, over 80 employees including 5 senior engineers, annual output value of RMB 50 million.

• Equipment — two 3 kW laser cutting machines, ten CNC spinning machines, plus hydraulic presses, vertical lathes and more than ten other sets.

• Product breadth — more than 100 standard products, plus non-standard fans designed to customer requirements.

• Export experience — shipments to Europe, North America, Southeast Asia and the Middle East, with familiarity with local voltage and frequency, packing and documentation.

Frequently Asked Questions

1. What is the minimum order quantity? Confirmed case by case by model, configuration and project; state your quantity at enquiry. Single-unit trials and volume orders can both be discussed.

2. How long is the lead time? It depends on size, motor configuration, voltage and frequency and quantity. Once specifications are fixed we issue a production schedule and agree it in the contract.

3. Can the motor suit our power grid? Yes. Motors can be supplied for 220/380 V at 50/60 Hz; specify the destination voltage and frequency when ordering.

4. Do you support custom designs and OEM? Yes. Beyond the 100-plus standard products we design non-standard fans to customer requirements, and OEM or private-label arrangements can be discussed.

5. What certifications do you hold? ISO9001:2015 certification, CE conformity for EU export, an explosion-proof certificate and third-party inspection reports, all available for review.

6. We do not know our system resistance. Can you help? Yes. Send the application, dimensions, air change rate, duct length and elbow count, medium temperature and dust content, and our engineers will size the fan.

Request a Quote

Email your requirements to joe@zifengfan.com: airflow (m³/h), total pressure (Pa), medium temperature, dust content, supply voltage and frequency, installation arrangement, quantity, and port of shipment or destination country. The more complete the data, the more accurate the quotation; if parameters are not fixed yet, describe the duty and we will calculate them.

You can also call +86-576-86353999 to discuss technical requirements, drawing approval and packing and shipping with our export team. Zhejiang Zifeng Fan Co., Ltd., Xiayuanshan Industrial Zone, Daxi Town, Wenling City, Zhejiang Province, China.

The range also covers the 4-72C belt-driven centrifugal fan, 9-19 and 9-26 high-pressure ventilators, CF-11 and DF low-noise multi-wing fans, the YN5-47 boiler fan, HTFC cabinet fans, XGB vortex blowers and