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E-coli bacteria E-coli bacteria

You have a filtered air supply system? The the filters were recently changed out? Should be all compliant then?

Sorry team, its not quite that easy. Particulate matter is coming through those air filters, as we speak!

To quote this Camfil article,  with outdoor air carrying 200 to 1,500 bacteria per cubic metre, an air-conditioning system with a capacity of 10,000 m3/h can potentially take in 2 to 15 million bacteria each hour and seriously contaminate food & beverage production

Scary stuff!

All air filters are designed to capture a percentage (important point,) of the particulate matter (i.e. dust, soot, smoke, pollen, mould, bacteria) suspended in the air passing through them.

(And that’s making an assumption that there are no leaks around the filter holding frames or supply air ducting – letting 100% of that particulate matter through!)

So what happens to the percentage that is not trapped in the filters?  It all passes through to the clean side of your air filters and travels on through the components of your ventilation system, eventually finding its way into your clean factory environment.

Dirty Condenser Coil Dirty condenser coil

Okay, lets be clear about this. We are only talking microscopic particles, within the acceptable air quality standards of your factory.

However, that does not take away from the fact that this particulate matter is building up internally in your HVAC system, clogging condenser fins, creating bacteria colonies around heat exchangers and contaminating supply air duct work.

If this accumulated foreign matter is not cleaned away and the surfaces sanitised, sooner or later it’s not hard to see that you are going to have issues with the air quality in your factory.

So, what is the answer?

A documented, annual hygiene cleaning schedule for your ventilation system will solve this issue for you. This will compliment the mechanical servicing and filter replacement programs you have in place currently.

This is not usually a task undertaken by factory operators or refrigeration engineers. Look for a reliable ventilation hygiene contractor who has the correct equipment, training and experience to clean and sanitise your:

  • filter rooms
  • air plenums
  • air supply fans
  • air supply ducting
  • condenser coils
  • condenser drain trays and pipework
  • air diffuser grilles

How often do I need to inspect and clean my Ventilation system?

This will depend on the environment outside your factory and the standard of air quality required inside your factory. The best answer is to engage an IAQ consultant to establish this for you.

In the meantime, as a guide, the standard BS EN 15780:2011 contains the following table for recommended inspection intervals.

Ventilation inspection frequency chart

Get this in place and you can rest easy that the amount of bacteria entering your factory is under control!

About the Author.


Matthew Prestidge photo

Matthew Prestidge is an Industrial Hygiene and Clean Air consultant for Presco Environmental Services in New Zealand.  Creating more sustainable environments on industrial sites since 2006, Matthew has seen the good, the bad and the ugly and knows what is required to “clean up”.

Matthew offers a free consultation and professional advice to the food industry for any industrial cleaning or hygiene issue.  Contact him at matthew@presco.co.nz


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