×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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!
  • Students Click Here

*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

Jobs

Acid Digestion Hood

Acid Digestion Hood

Acid Digestion Hood

(OP)
I am a new facilities engineer at a local university. We have a system (designed by an outside consultant) that uses flow control valves on VAV fume hoods. The hoods are used extensively for acid digestion (boiling off hydrochloric acid, hydrofluoric acid, nitric acid, OR hydrogen peroxide). After operating ~18 months, response on one valve diminished. Investigation revealed a build-up of acidic matter on the low-pressure side of the (vertically-oriented) valve cone. For those who have experience with this type of operation, is a constant-volume hood preferred for this application?

Thanks in advance.

RE: Acid Digestion Hood

I don't get involved with this type of matter, but that could change in the near future with one of our clients. I am thinking if condensation of acid fumes could be the problem and perhaps raising the temperature of the acid laden air may control this type of problem. Perhaps the buildup of acid matter is a surface corrosion problem?

RE: Acid Digestion Hood

Have you got wash down rings on the exhaust duct? All acid exhaust ducts need to be washed down with water after use.Generally acid exhaust ducts go straight up to the roof to make the washdown easy.Looks like the flow measuring pitot holes have been blocked by deposits.I have not used valves on acidic exhaust ducts in the past.Even with a wash down nozzle water can get into the holes and stay there inside the tube.

RE: Acid Digestion Hood

You say nothing of the fans on this system. Is the system VAV? Mixing CV and VAV hoods on the same hood may cause problems.

Call the Engineer who designed this, you won't be able to bootstrap as solution on a web forum.

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!


Resources