Air duct cleaning in industry

Industrial air duct cleaning: which contamination do you encounter?

The type of contamination determines almost everything: the method, the brush, the safety measures and how often you need to return. An overview of the most common situations:

Additional hygiene and dust rules apply to food and flour. They are worked out under ducts in food processing plants and under extraction in the bakery.

Why contaminated extraction ducts in factories are a health and safety issue

In many factories an extraction installation is a control measure. The Dutch sector organisation Volandis mentions a flexible extraction system close to the work as a solution for metalworking, and gives limit values for inert dust of 10 mg/m³ inhalable and 5 mg/m³ respirable over 8 hours. If the extraction works less well because the duct is clogging up, exposure on the shop floor rises.

Article 4.5 of the Working Conditions Decree (Arbobesluit) states that when contaminated air is removed, sufficient clean air must be supplied at the same time. And article 6.2 requires that ventilation installations are always ready for use. A half blocked duct is not.

In the United Kingdom it is even more concrete: the HSE requires local exhaust ventilation to be thoroughly examined and tested at least every 14 months, with the report kept for 5 years. That is not a Dutch rule, but it is a useful reference point for your own maintenance plan.

Dust explosions and ATEX: what does that mean for cleaning?

Fine wood dust is explosive. The Dutch website Brandveilig.com highlights extraction installations, spark detection and ATEX as points of attention in the wood processing industry. That also applies during cleaning: you are loosening dust in an enclosed space, and that is exactly what you need to be careful with.

Agreements for cleaning in dust sensitive installations

• Work from the company's explosion protection document: which zones are there and which equipment is permitted in them?
• Remove coarse dust first with a suitable industrial vacuum cleaner, so no more dust is stirred up than necessary.
• Shut the installation down, lock it out and check that spark detection and extinguishing systems are in the correct setting.
• Use negative pressure and seal off the run, so loosened dust is removed immediately.
• Record what you cleaned and what was not accessible.

Whether a specific machine is suitable for an EX zone is something to check with Lamers before you use it. Do not assume that a standard 230 volt version is automatically allowed there.

Which equipment suits extraction ducts in industry?

Industrial ducts are often larger and longer than in an office. So look first at the size and the length.

The Electric duct brushing machine for cleaning contractors is the workhorse choice for round and square ducts up to 600 mm. In the large package, Danduct also supplies an aggressive brush set for stubborn deposits. For small compressed air lines or places where you want to see what you are doing, compressed air duct cleaning for cleaning contractors is a good fit.

For comparison: LIFA AIR has the CombiCleaner 40 for ducts from 400 to 1,200 mm with a 40 metre shaft. If you work with such sizes, ask Lamers for advice on the right machine. The whole range is listed under duct cleaning kit for cleaning contractors.

Planning: when do you clean industrial ducts?

There is no fixed frequency. A good schedule follows from three things: how much dust enters the system each week, how quickly the extraction power declines, and what happens if things go wrong.

1. Measure the performance. After cleaning, record the air velocity or negative pressure at the extraction points. That is your baseline.
2. Inspect periodically. Look through inspection hatches or with a camera to see how quickly the layer builds up.
3. Link it to downtime. Schedule cleaning during the planned maintenance shutdown, so production does not suffer.
4. Record everything. Keep readings and photos, so you can compare next time.

Make sure there are enough inspection openings. The Eurovent recommendation mentions openings at most 10 metres apart or after two bends of 45 degrees or more, and for ducts above 500 mm a hatch of at least 500 by 400 mm. With duct sealing balloon for cleaning contractors you keep the dirt inside the duct while you work.

Legionella in cooling towers and air humidification in industry

Not every industrial risk is dust. Anyone with wet cooling towers or air humidification has to deal with legionella. Article 4.87b of the Working Conditions Decree (Arbobesluit) regulates measures for air humidification installations. According to the National Institute for Public Health and the Environment (RIVM), wet cooling towers require a risk analysis, a management plan and a logbook, with ISSO 55.3 as guidance.

A clean duct downstream of the humidifier is part of that management. Include it in your inspection round. If you are a cleaning contractor carrying out these jobs for factories, read how to choose equipment per assignment under duct cleaning business.

Checklist for industrial ductwork cleaning before you start

The points above come together in one practical checklist. Go through it with the plant manager or the person responsible for health and safety before any work starts. It adds no new rules, it simply puts the steps from this page in order.

• System: is this general ventilation or process extraction, and which standard or risk assessment applies?
• Substance: what is in the duct, and what do the substance data say about fire, explosion and exposure?
• Zones: are there EX zones, and is the equipment you plan to use allowed there?
• Access: are there enough inspection openings, and are the duct sizes within the range of your machine?
• Isolation: is the installation shut down and locked out, and are spark detection and extinguishing systems in the right setting?
• Containment: is the run sealed and under continuous negative pressure?
• Record: are baseline readings, photos and any inaccessible sections written down?

If one of these points cannot be answered, that is the question to put to the client or to Lamers first.