Product Review: Iris Dampers in Multiple Sizes

Smooth, precise airflow control

When you need to fine-tune airflow in a ventilation system, an iris damper is one of the most precise tools for the job. Unlike standard volume control dampers with single blades, an iris damper uses overlapping metal petals to adjust the opening evenly all around the duct. This design keeps airflow centred and reduces turbulence, making it perfect for systems that need accurate control.
We stock manually operated iris dampers in galvanised steel across a range of sizes, from 80mm for smaller duct runs to 400mm for large-scale installations.

Why customers choose iris dampers

We’ve supplied these to a wide mix of projects, from air balancing in offices to industrial extraction systems, and they’re a favourite for commissioning engineers because of how precisely they can be set.
Key benefits:

• Even airflow adjustment – The iris design maintains airflow symmetry, improving accuracy.
• Low turbulence – Great for airflow measurement points or where smooth flow is essential.
• Built-in measurement ports – Many iris dampers include small test points for airflow reading, making commissioning easier.
• Strong galvanised steel body – Long service life, even in busy commercial or industrial environments.
• Simple manual operation – No tools needed for everyday adjustments.

Sizes available

80mm, 100mm, 125mm, 150mm, 160mm, 200mm, 315mm, and 400mm. If you’re not sure which size matches your ductwork, we can help you choose the right fit.

Where we’ve seen them used

• Ventilation balancing in office and retail HVAC systems
• Laboratory extraction where stable airflow is essential
• Industrial ducting for fine control of extraction rates
• Cleanroom environments to regulate supply air precisely

One customer told us they swapped their standard dampers for iris types during a commissioning phase and saw far more consistent airflow readings.

Things to keep in mind when it comes to iris dampers

• These are manual dampers, if you need remote or automated control, a motorised option would be better.
• While robust, they’re designed for low to medium pressure systems.
• Make sure there’s space to access the adjustment mechanism once installed.

FAQ

Q: What is an iris damper used for?

An iris damper is used to control and balance airflow in ducting systems. Its unique petal design allows for smooth, even adjustment, making it ideal for applications where precise airflow regulation is required.

Q: How does an iris damper differ from a standard volume control damper?

A standard damper uses a flat blade to control air volume, which can create turbulence and uneven flow. An iris damper adjusts from the centre using overlapping blades, keeping airflow balanced and symmetrical. This makes it particularly good for airflow measurement points.

Q: Can an iris damper be used for airflow measurement?

Yes. Many iris dampers have built-in measurement ports, so you can connect an airflow meter directly without needing extra fittings. This is one reason they’re so popular with commissioning engineers.

Q: What material are these dampers made from?
Ours are made from galvanised steel as standard, which is durable, corrosion-resistant, and suitable for most commercial and industrial ventilation systems.

Q: Are iris dampers motorised or manual?

The ones we stock are manual, adjusted by hand. If you need remote or automated control, a motorised option can be specified.

Q: Can I use an iris damper in high-pressure systems?

They’re generally designed for low to medium pressure ductwork. For very high-pressure systems, you may need a reinforced damper or a different design altogether.

Q: What sizes are available?

We stock sizes from 80mm to 400mm. If you’re unsure which size fits your ductwork, we can help you match the right damper to your system.

Q: Is installation complicated?

No – they install just like any other inline circular duct component. The main thing to remember is to leave enough space to access the adjustment mechanism.

Written by Enya Kerry – Office Manager at Ducting Express

With over four years in ducting and ventilation systems, and W201 and P601 certifications, I’ve helped customers select the right dampers for everything from small office refits to large industrial air handling projects.