Backward-curved centrifugal
Efficient and stable on clean to lightly dusty gas. The usual choice behind bag filters and ESPs.
Typical use Boilers, dryers, bag-filter exhaust
ID fan & centrifugal blower manufacturer · Ahmedabad, India · Since 1997
ID fans built for your duty point
Induced draft fans sized to your flow, pressure and gas – and a knowledge hub that shows how they work, how to choose one and how to keep it running.
- ISO 9001:2015 & CE certified
- 1500+ projects · 500+ industrial clients
- Quote within one working day
Hot gas indrawn through the inlet by suction
To the chimneypressure raised, gas sent up the stack
Drag to rotate · tap the dots
Since 1997fans & blowers built in Ahmedabad
1500+projects delivered
ISO 9001certified, CE marked
1997
Building fans & blowers since
1500+
Projects delivered
500+
Industrial clients
Custom
Every fan built to your duty point
ISO 9001
Certified by TÜV India
CE
Marked equipment
500+industrial clients trust AS Engineers1500+ projects · ISO 9001:2015 · since 1997
Why it matters
The fan that decides how your plant breathes
An ID fan is the engine of the draft system. When it is right, the boiler, dryer or filter behind it runs well. When it is wrong, everything downstream suffers.
Keeps the draft negative
Gas and dust stay inside the duct, not in your plant. Safer for people, cleaner for the site.
Stabilises combustion
A steady furnace draft keeps the flame stable and the air-to-fuel ratio under control.
Saves power
The right blade shape and a speed drive can cut a large share of the fan’s running cost.
Built for hot, dusty gas
Wear liners, tough blades and cooled bearings for gas that would destroy an ordinary fan.
Easy to keep running
Balanced impellers, sensible access and genuine spares keep shutdowns short.
Sized to your duty
We fit the fan to your flow, pressure and gas – not the other way round.
How it works
Suction in. Pressure out.
- 1Pulls
The impeller spins and throws gas outwards, so the pressure at the fan inlet drops below the surrounding air.
- 2Drafts
That suction – the induced draft – draws flue gas or process exhaust out of the furnace, dryer or hood.
- 3Pushes
The scroll casing turns the speed into pressure and sends the gas through the outlet duct to the stack.
- 4Keeps negative
The system stays slightly below atmospheric pressure, so hot gas and dust do not leak out into the plant.
Fan types
Pick the blade for the gas
Clean gas, dusty gas or abrasive gas each need a different impeller. Here are the four designs we are asked about most.
Radial / paddle-blade centrifugal
Self-cleaning, wear-resistant blades for heavy dust, sticky or abrasive gas.
Typical use Cement, coal, biomass, sinter, wood dust
Airfoil centrifugal
Highest efficiency and lowest noise on clean gas – the power-saving option.
Typical use Power plants, large clean-gas duties
Axial-flow
Very large volumes at low pressure in short duct runs.
Typical use Cooling, tunnel and plant ventilation
Duty-point calculator
How much power will your fan need?
Move the sliders – see shaft power, a suggested motor size and the yearly power cost. 20 seconds.
0 kWshaft power needed
- Gas density at this temperature
- 0 kg/m³
- Same duty on standard (20 °C) air
- 0 mmWC
- Suggested motor
- 0 kW
- Power cost per year*
- ₹0
*Indicative only: shaft power = flow × pressure ÷ (3600 × 1000 × fan efficiency). The motor is rounded up to the next standard size with a 10% margin. Final selection depends on the fan curve, the system curve and the dust and gas data – we check it for you free.
Industries
ID fans in the plants we serve
One guide per industry – how the fan is used, what to watch and how to specify it.
Industries
ID Fans in Wastewater Treatment: Selection, Odor Control, Scrubber Duty & Maintenance Guide
ID fans in wastewater treatment plants are used to pull contaminated, odorous, humid, or process exhaust air through ducts, scrubbers, biofilters, chimneys,…
Industries
ID Fans in Textile Manufacturing: Selection, Dust Control, Exhaust & Maintenance Guide
In textile manufacturing, an ID fan is not just a general exhaust fan. It is a process-side air movement component that helps…
Industries
ID Fans in the Spray Dryer Industry: Selection, Working, Problems, and RFQ Guide
An ID fan in a spray dryer controls exhaust draft, removes moisture-laden air, pulls fine powder through the recovery and pollution-control path,…
Industries
ID Fans in the Pulp and Paper Industry: Applications, Selection, and Maintenance Guide
ID fans in the pulp and paper industry are used to pull hot gas, moist air, fumes, dust-laden exhaust, and process vapours…
Industries
ID Fans in Power Generation: Practical Guide for Power Plant Draft, Flue Gas, and Reliability
In a power plant, an ID fan is not just a general exhaust fan. Its main job is to pull flue gas…
Industries
ID Fans in Hot Mix Asphalt Plants: Selection, Draft Control, and Maintenance Guide
In a hot mix asphalt plant, the ID fan is not just an exhaust fan. It controls the draft through the dryer…
Selection checklist
Six facts we need to size your ID fan
Do not worry if you do not have all of them. Send what you know – our engineers will help with the rest.
1Gas flow
Actual volume in m³/hr at the operating temperature – not normal m³/hr.
2Pressure
Total static pressure the fan must overcome, in mmWC or Pa, from ducts, filter and stack.
3Temperature
Normal and peak gas temperature. It sets density, materials and bearing cooling.
4Gas & dust
Moisture, corrosive gases, dust load and particle type – they decide blade shape and lining.
5Drive
Direct, belt or coupling drive, speed control (VFD) and motor rating.
6Site
Altitude, ambient temperature, hours of running and available space.
Engineering & service
We build the fan – and keep it running
Supply, site support and after-sales from one team, for the whole life of the fan.
Tailor-made quotations
From a clear one-pager to a full techno-commercial offer – as much detail as you need.
Performance analysis
Not sure of the flow or static pressure you need? Our engineers work out the parameters with you and design the fan around them.
Engineering surveys
Bearing, stress, shaft critical-speed and thermal analysis to find the root cause of a fan problem – and a fix.
Retro-fitment
We measure and draw any fan, or any part of it, on site – whoever made it.
Knowledge hub
Straight answers from the people who build fans
Blogs
FD Fan vs ID Fan: Difference, Working, Selection and Boiler Draft Role
FD fan vs ID fan is not a question of which fan is “better.” An FD fan pushes combustion air into a…
Blogs
Boiler ID Fan: Function, Importance, Selection & Maintenance Guide
A boiler ID fan removes hot flue gases from the boiler system and helps maintain negative draft inside the furnace, gas path,…
Blogs
ID Fan Installation: Practical Checks Before Site Commissioning
ID fan installation is not only a mechanical placement job. A correctly installed ID fan must match the duct system, foundation, motor…
FAQ
Questions buyers ask us
What is an ID fan?
An ID (induced draft) fan is a fan placed at the outlet side of a boiler, furnace, dryer or filter system. It pulls flue gas or process exhaust through the equipment and pushes it up the chimney, keeping the system at slightly negative pressure.
What is the difference between an ID fan and an FD fan?
An FD (forced draft) fan pushes fresh air into a boiler or furnace. An ID fan pulls the gas out. Balanced-draft boilers use both, so the furnace stays just below atmospheric pressure.
Where are ID fans used?
In boilers and power plants, cement and steel plants, spray and fluid-bed dryers, pulp and paper mills, textile and food plants, galvanizing and asphalt plants, wastewater treatment and anywhere hot or dusty gas has to be drawn through filters and scrubbers.
Is an ID fan the same as an exhaust fan?
Not quite. An exhaust fan usually moves clean, cool air for ventilation. An ID fan is a process fan: it handles hot, dusty or moist gas at higher pressure, so it needs stronger materials, a suitable blade shape and cooled bearings.
What types of ID fan are there?
Most are centrifugal: backward-curved or airfoil blades for clean gas, radial or paddle blades for heavy dust. Axial fans are used for very large volumes at low pressure.
Do you make ID fans or only publish guides?
Both. AS Engineers designs and builds ID fans and centrifugal blowers in Ahmedabad, India, and publishes this knowledge hub so plant engineers can specify, run and maintain them better.
Tell us your duty. We will size your ID fan.
Share air flow, pressure, temperature and gas – get a fan recommendation and price within one working day.