Whether you're installing a bathroom exhaust fan, connecting a kitchen chimney, setting up an HVAC system, or building a grow room ventilation network, the right duct pipe makes all the difference. Astberg Ventilation offers a premium range of PVC flexible duct pipes, insulated exhaust pipes, and ventilation ducting in multiple sizes — engineered for silent, efficient airflow in residential, commercial, and industrial applications across India.
What Is a Duct Pipe?
A duct pipe (also called a ventilation duct, exhaust pipe, or flexible ducting) is a tube or conduit that channels air from one point to another — typically from a fan or air handling unit to an outdoor exhaust point. Duct pipes are a core component of any ventilation system, carrying away stale, humid, or contaminated air and replacing it with fresh, filtered air.
They come in rigid and flexible varieties. Flexible duct pipes — like those offered by Astberg — are particularly popular because they can bend around corners and obstacles without additional fittings, making installation significantly faster and easier.
Why Choose PVC Flexible Duct Pipe?
PVC flexible duct pipe combines the structural strength of a wire-reinforced core with the lightweight flexibility of PVC cladding. Here's why it's the preferred choice for most installations:
- Flexibility — Bends and routes around beams, joists, and corners without special fittings
- Leak resistance — Smooth inner bore and tight-fitting construction minimize air leakage and pressure loss
- Light-blocking — The thick grey PVC outer layer prevents light leaks, making it ideal for grow tents and dark environments
- Insulation — Insulated variants prevent condensation on the duct surface, protecting ceilings and walls from moisture damage
- Noise reduction — Flexible construction absorbs vibration from the fan motor, keeping operating noise to a minimum
- Durability — Resistant to common chemicals, humidity, and temperature variations found in kitchens, bathrooms, and basements
Astberg Duct Pipe Range
Astberg stocks PVC flexible insulated duct pipe in the most commonly specified diameters for Indian residential and commercial projects:
100mm (4") Flexible Duct Pipe — AFD100
The 100mm duct pipe is the standard diameter for bathroom exhaust fans, toilet ventilation, and small inline fans. At 10 metres per roll, it provides enough length to connect a fan to an exterior wall in most home installations. The thick grey PVC cladding blocks light and prevents condensation.
- Diameter: 100mm / 4 inch
- Length: 10 metres (32 feet)
- Use cases: Bathroom fans, toilet exhausts, small inline fans, grow room ventilation
315mm (12") Flexible Duct Pipe — AFD315
The 315mm duct pipe is designed for high-volume ventilation applications — commercial kitchens, large HVAC systems, industrial exhausts, and fresh air units. The larger bore handles significantly higher airflow rates while maintaining low static pressure.
- Diameter: 315mm / 12 inch
- Use cases: Commercial kitchens, HVAC connections, industrial ventilation, large inline fans
Additional sizes — 125mm, 150mm, and more — are available. Contact Astberg for custom sizing requirements.
Primary Keywords & Use Cases
| Keyword | Where It Applies |
|---|---|
| Duct pipe | All ventilation connections |
| PVC flexible duct | Bathroom, kitchen, inline fan connections |
| Exhaust pipe | Kitchen chimney, bathroom exhausts |
| Ventilation duct | HVAC, fresh air units, ERV/HRV systems |
| Insulated duct pipe | Areas prone to condensation |
| Chimney pipe | Kitchen chimney exhaust connections |
| Aluminum flexible pipe | High-temperature applications |
| Flexible ducting India | Residential & commercial projects across India |
| 100mm duct pipe | Domestic bathroom and toilet fans |
| 315mm duct pipe | Commercial and industrial ventilation |
How to Choose the Right Duct Pipe Size
Choosing the correct diameter is critical for performance. Using a duct pipe that is too narrow creates back-pressure, reduces airflow, increases noise, and shortens fan life. Using one that is too large wastes space and reduces air velocity, causing moisture to condense inside the duct.
General sizing guide:
- 75mm – 100mm: Bathroom exhaust fans up to 150 m³/h, toilet fans, small inline fans
- 125mm – 150mm: Kitchen exhaust fans, medium inline fans (200–400 m³/h), bedroom ventilation
- 200mm – 250mm: Large inline fans (500–800 m³/h), whole-house ventilation, ERV/HRV connections
- 315mm+: Commercial kitchens, industrial exhausts, HVAC air handling units
Rule of thumb: Always match the duct pipe diameter to the outlet diameter of your fan or grille. Reducing pipe size downstream creates turbulence and noise.
Duct Pipe Installation Tips
- Keep runs as short and straight as possible — every bend adds resistance. A 90° bend is equivalent to approximately 1–2 metres of straight duct.
- Secure every 1–1.5 metres — use duct clips or saddle clamps to support the flexible pipe and prevent sagging.
- Seal connections with duct tape or hose clamps — airtight connections prevent leaks that reduce system efficiency.
- Avoid compressing the duct — flexible duct should be fully extended. Compressed or bunched duct dramatically increases resistance.
- Insulate in cold areas — in unheated loft spaces or external walls, insulated duct prevents condensation that can damage ceilings.
- Slope towards the exhaust — a slight downward gradient towards the outdoor terminal prevents condensation from pooling inside the duct.
Frequently Asked Questions
- What is the difference between flexible duct pipe and rigid duct pipe? Flexible duct pipe can bend around obstacles without additional fittings, making it faster to install in confined spaces like ceiling voids and wall cavities. Rigid ductwork offers lower air resistance over long straight runs and is preferred in commercial systems where every Pascal of pressure counts. For most residential applications, flexible PVC duct pipe is the practical choice.
- Can I use PVC flexible duct for a kitchen chimney? Yes. Astberg's PVC flexible duct pipes are suitable for standard kitchen chimney connections. For very high-temperature applications (above 70°C), consider an aluminium flexible duct instead.
- What length of duct pipe do I need? Measure the distance from your fan outlet to the exterior exhaust point, then add 10–15% for bends and routing around obstacles. Astberg's 100mm duct pipe comes in a 10-metre roll — sufficient for most single-room installations.
- Is insulated duct pipe necessary? Insulated duct pipe is recommended whenever the duct runs through an unheated space (loft, external wall cavity) or where the air being exhausted is significantly warmer than the surrounding environment. Without insulation, warm moist air condenses on the cold duct surface, causing water pooling and potential mould growth.
- What is the best duct pipe for a bathroom fan? A 100mm (4") PVC flexible insulated duct pipe is the standard choice for most domestic bathroom exhaust fans in India. The 100mm diameter matches the outlet of the majority of bathroom inline and ceiling fans, and the insulated construction prevents condensation in wall and ceiling voids.
- How do I connect flexible duct pipe to a fan? Slide the end of the flexible duct over the fan's spigot outlet and secure it with a hose clamp or several wraps of self-adhesive duct tape. Ensure the connection is airtight. Repeat at the grille or wall terminal end.
Why Buy From Astberg Ventilation?
Astberg is one of India's leading specialists in home and commercial ventilation, with a complete product range from fans and ERV/HRV units to grilles, diffusers, and accessories including duct pipe. When you order from Astberg:
- Free shipping on orders over ₹5,000
- Fast PAN India delivery within 5 working days
- Genuine products — every Astberg product is quality-tested before dispatch
- Expert support — 24/7 online support for installation and product queries
- Flexible payment — all major cards, UPI, and RuPay accepted
Related Products
Looking to complete your ventilation system? Pair your duct pipe with:
- Inline Fans — Silent mix flow and circular duct fans in matching diameters
- Ceiling Exhaust Fans — Quiet, efficient fans for bathrooms and utility rooms
- HRV / ERV Units — Heat and energy recovery ventilators for whole-house fresh air
- Ventilation Accessories — Grilles, diffusers, backdraft shutters, and wall cowls
