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Ventilation exhaust fans in production?

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Posted 26 October 2022 - 05:55 PM

Hello everyone,


I work in a bakery and our ovens release a lot of steam when we open the doors. We usually have to crack it to give them a moment to release most of the steam before we can open the doors fully and remove the racks of product. 


Our maintenance lead just informed me that he was asked to remove the window in that room to install this fan:




The window is in the wall that separates production from the outside of the building. Our mix, bake, and pack areas are all in one room with walls dividing the areas but no doors, there are just open walkways between the raw and RTE areas. The proposed window where this fan would go is in the bake area but near one of those openings to RTE side.


Can anyone please help explain to me why this is a good or bad idea so I can discuss the risks with our management team? I am not knowledgeable enough about appropriate food processing ventilation, but this doesn't seem like the best solution to me.


Thank you!


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Posted 26 October 2022 - 06:33 PM

From seeing the picture, if you would decide to move forward, you'll need to install a finer screen to keep insects out.  Make sure it is indeed exhausting out.  Make sure it is being cleaned at a defined frequency and I would test at a defined frequency with some air plates near and around just to cover your basis.  To me it all depends on how close this will be and your defined risk.  However, I tell people to trust their gut.  If you feel there is a better solution, bring that up and work with the team for a solution that would meet all of your needs.


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Posted 26 October 2022 - 08:12 PM

Hey! We also had a lot of steam.
Luckily we had a 'newer' oven. We programmed it to open the exhaust in the oven 2 minutes before the end of the cycle.
Do you have that possiblity?


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Posted 27 October 2022 - 02:35 PM

Exhaust isn't a problem, but making sure that it is not letting anything back in is.  I would expect there to need to be some filtration to protect the hardware from the dust common to a bakery and prevent intrusion of pests or filth.  The linked device doesn't cover any of that.


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Posted 27 October 2022 - 06:42 PM

Agree with the above that you'll need a finer screen on the fan.  This is something that your maintenance dept can handle, just make sure the new screen is covered on your internal audits that currently check the window's screen (current window does have a screen, right?  :hypocrite: )  Also agree you'll need to make sure the fan is covered under your master sanitation schedule.


I'd argue the fan is probably better than a window in the long run, as open windows leave opportunities for air to enter and contaminate your production area.  But when you introduce an exhaust fan, you'll have to account for where air is entering your building to replace the air being sucked out.  This will count on your door and window seals across the plant being in good repair, building maintenance itself being up to date.  


As a way to cover your plant after the install, you might want to collect some extra air plate testing.  Choose a series of spots not covered under your standard environmental monitoring, take a sample prior to installing the fan (routine operations, window open, etc).  Take 2-3 tests in the same spots in the first couple weeks of operating the fan, and see if a change is noted.  I think this would be sufficient to validate the exhaust fan is not going to contribute to problems.  For bonus points, include the pest control results in your validation before and after to show it has not led to increased insect activity.


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Posted 21 November 2022 - 07:45 PM

You should also research negative pressure and make-up air. Negative pressure allows contaminants to be "sucked in" other building openings such as doors leading to production areas. If you do not have ventilated air lock entries into processing areas the negative pressure could allow these contaminants to enter. Balancing with another 24" intake somewhere else in the building (preferably 5% - 10% more than exhaust). The higher intake volume will allow for better evacuation where desired, as well as keeping positive pressure all other times and, as stated above, filters on the intake and insect proof screens on the exhaust.

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Posted 29 November 2022 - 07:18 PM

I'm not sure what the goal is by installing the fan (condensation, comfort, etc) or the design of your facility and air handling system.   thus its hard to give you a good recommendation as to "good" or "bad" idea.  


I would suggest you contact an industrial HVAC person.   I think they will be able to ensure you are not addressing a problem and causing another air movement problem.   perhaps maintenance is knowledgeable enough and has given this thought.   However, I agree with you- a garage fan installed across the way doesn't scream "best solution".


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