Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

exhaust ventilation alkaline cleaner tank

exhaust ventilation alkaline cleaner tank

exhaust ventilation alkaline cleaner tank

I have a small black oxide line in my plant.  The first (cleaner) tank is caustic soda heated to 140°F.  There are vapors coming off the tank that cause an unpleasant odor.  I had an air quality audit done a while back and the industrial hygienist recommended local exhaust ventilation on this tank.  The vapors consist of sodium hydroxide, sodium metasilicate and /or glycol ether.  He said I need 190 cfm/ft^2 of surface area or 956 cfm total (5.03 ft^2).  There is an overhead crane above the tank, so I can't put  a hood over the top.  I will have to install ductwork on the sides of the tank and draw the vapors underneath and then somewhere. Now my question:

What do I do with the air and vapors?  Can I filter it or condense it and then blow the air outside, or just blow it all outside?  If I blow it outside do I need to allow for makeup air to keep the doors from being sealed shut?  Unfortunately the guy that did the audit is no longer at my insurance company and I haven't been able to get in contact with anyone there that could help me.  Any ideas?

RE: exhaust ventilation alkaline cleaner tank


The most usual solution to your problem is a push-pull system consisting of forced air outlets across one side of your tank with inlets (exhaust) on the other.  The system essentially functions as an air curtain over the tank to capture the fumes.  Given the contaminants in your airstream, you might want to put in a plain water scrubber to remove the contaminants before exhausting the air outside.  Depends on the concentrations, odor levels and your environmental permits.  Filtration might work, depends on the level of aerosol in your exhaust.  Aerosols tend to gum up dry filters, so you might want to avoid those.  The thing to do first is to determine the level you might have.  You can estimate these levels from algorithms for caustic baths found in literature from the EPA, AWMA and the American Association of Industrial Hygienists.  From there, you can determine what is then needed in the way of control before exhausting the airstream.  

RE: exhaust ventilation alkaline cleaner tank

The scrubber would work well. The scrubber will need to be bled at a low flow rate. make sure COD is not too high in the bleed stream for your local discharge.

RE: exhaust ventilation alkaline cleaner tank

The push-pull system would only require 75 CFM/ft2 (vs 190).  Normally, this system is desirable if your tank width is > 36".  The "Industrial Ventilation" published  by the ACGIH is well documented about this subject.

The major atmospheric contaminant will be an alkaline mist and/or steam that can be treated with a mist eliminator.  However, this equipment might not be necessary  - you might be able to blow it outside, check with your local authorities.  

RE: exhaust ventilation alkaline cleaner tank

Thank you all for your help.  I am dealing with a fan company that specializes in handling this type of situation and they are designing a system for me.  Thanks again.

RE: exhaust ventilation alkaline cleaner tank

if you have more information about this specialized fans co. or their site is known please inform us this will be of a great help with many thanks.

RE: exhaust ventilation alkaline cleaner tank

Hopefully I am not violating any policy by mentioning them here.  The name of the company is MAPCO (Midwest Air Products) at midwestair.com.

RE: exhaust ventilation alkaline cleaner tank

Once the air requirements have been established, what is the best method of determining blower size?

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close