Local Exhaust Ventilation Duct Cleaning

• By: Craig Booth
• On: 15/09/2009 11:34:13
• In: Uncategorised
• Comments: 0 Add

I don't normally like to sell our duct cleaning services, "with a policeman's hat on", but sometimes it is unavoidalbe. Especially in a highly regulated area like industrial occupational hygiene.

Here's an example of what I call "selling with a truncheon in your hand"

But the points are well made. Local Exhaust Ventilation (LEV, provided typically in the industrial workplace to remove hazardous airborne contaminants ranging from sawdust, through to gases and fumes) extract ductwork can get dangerously dirty. They fall, in the UK, under the Control Of Substances Hazardous to Health (COSHH) Regulations, and regular functional testing should be carried out to prove that they continue to provide the 'control measure', i.e. reliably pull out the contaminant. Similar Regulations whereby effective control measures should be in place for control of workplace contaminants exist in most countries.

Often the engineer responsible for the systems wants to clean the LEV system, because he knows that's the right thing to do, but he needs 'The Law' to convince his superiors that something should be done.

Of course LEV sytems should be designed so that the contaminant stays airborne and does not settle out on the duct surfaces..but it doesn't always work out like that. Not by a long chalk!

You can see deposits build up which will impede airflow (and so stop the system properly pulling workplace contaminants away from the worker's breathing zone). Often enough air velocity can be slowed down by a gradual accumulation of dusts, or by a larger item like a paper wrapper, piece of packaging, beer can (no really! where's a better place to hide the evidence of illicit drinking?), which then allows finer dirt to build up.

Besides airflow reduction, there can be an issue with the flammability of the material caught in the duct. The material can act as a fuse and carry fire through the building

Here's an example of an industrial laundry extract duct whose cross-sectional area has been reduced. Not only was there an efficiency problem (the hot, moist air was not being properly removed, also there was significant fire risk - laundry extracts go up quite often).

Just a quick commercial break for Triventek duct cleaning equipment: the rotating brush nozzle is perfect for cleaning some of the more adherent deposits you can find in LEV extracts. You have the combination of Jetvent Tornado nozzle 'sticking' to the duct surface. PLUS the cleaning aggression of a wire brush spinning at 9-11,000 rpm.

The Rotating brush nozzle only works on circular ductwork, but that's no problem since the great majority of LEV ductwork is circular.

One warning note: do make sure that you know what the contaminant is and how to deal with it, from a toxicity point-of-view, and possibly from a flammability point-of-view