June 17, 2019, 03:10:53 PM
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Topic: Fume Hood Exhaust Questions  (Read 2018 times)

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Offline EvolvE

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Fume Hood Exhaust Questions
« on: October 09, 2018, 11:20:06 PM »
So I have the Labconco Protector Workstation ductless fume hood.  It was working great until the filters weren't.  It is located in my garage and a duct was added from it's previous owner to vent outside but I haven't had the need for that yet.  However, I knew the filters were ready for a change and after getting some sulfuric acid vapors hit me yesterday, it's on lockdown until the new filters arrive. 

I mostly work with phosphoric acid, concentrated sulfuric acid, formaldehyde, and other reagents.  The filters WILL capture formaldehyde vapors, but I'm thinking now is the time to just get it vented outside for longevity. 

That being said, I am able to get piping outside, but not sure if a Type I PVC or 314 SS would be better.  What are your thoughts on getting any bypass vapors outside?  Also, what is the best way to determine if my airflow is sufficient, especially if I add ductwork?


Offline Borek

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Re: Fume Hood Exhaust Questions
« Reply #1 on: October 10, 2018, 06:18:24 AM »
Are you sure there are no local regulations that you have to follow?
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Offline Arkcon

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Re: Fume Hood Exhaust Questions
« Reply #2 on: October 10, 2018, 07:53:43 AM »
As was said, your home lab is required to follow local laws for release of reagent fumes.  You can look those up, and maybe ask local environmental agencies.  And you can work on that, at your pace -- research first, understand what compliance will mean/require, and make a decision.

You know what's being released, do you know what the filters can absorb?  What are they made of and what do they claim to absorb, and what chemistry is involved?

Offhand -- phosphoric acid and sulfuric acid aren't volatile.  However, working with can give off fumes -- mists of acids released from mixing, that sort of thing.  Controlling what you're doing will go a long way to longevity.  Carbon filters will absorb formaldehyde, so will dedicated organic vapor filters.  They become saturated at some point, then have to be discarded responsibly, and replaced.  That's a double cost.  Both thick PVC piping, or stainless ducting stand up to the vapors you listed, until they don't, then they have to be replaced.  It depends on your use.

There are meters that determine airflow.  Asa rule of thumb, if a piece of tissue paper is being drawn in when the sash is at working level, the fan is ding its job, and no impeded by a clogged filter or leaky ductwork.  But compliance with workplace regulations requires measurement of airflow with a calibrated gauge.
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Offline EvolvE

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Re: Fume Hood Exhaust Questions
« Reply #3 on: October 10, 2018, 12:24:54 PM »
Thanks for your responses.  I will make sure to check with local environmental agencies regarding this.  As of right now, I believe the only issue will be the carbon filters and their disposal as I'm not venting anything into the air yet.  That would more likely be down the line when I move into a dedicated shop.  Here are the filters my Labconco Protector Workstation uses.  I have 2 brand new ones on the way.


I believe these should cover everything I am doing.  Even with the filters, is it recommended to wear a face mask?  I have these from 3M: https://www.amazon.com/dp/B009POHLRC

Lastly, I am getting great flow with tissue paper held at the sash, it is being pulled in.  I would, however, like to get a calibration device if they aren't too expensive.  Any recommendations?  And are there any recommended devices I could use to make sure the vapor levels are below OSHA recommended levels, anything that can reduce the chances of harm is worth it in my opinion. 


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