×
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

Static Pressure Loss in Flex Duct Systems

Static Pressure Loss in Flex Duct Systems

Static Pressure Loss in Flex Duct Systems

(OP)
I am a draftsman/designer at an engineering firm, and most of my work is in HVAC Mechanical System design.  We recently did a project for a small school house where the contractor installed ALL flex duct instead of the hard duct we specified.

Typically, we would kick it back and have the contractor redo, but because we were not contracted for Construction Review and the installation was approved by the owner against our recomendations this installation will stay.

Although, I am working on As-Built drawings for the project and I am looking for a table that will give me Static Pressure Loss of Flex-Duct.  At this time I am unable to find anything that will provide me with the information I require to verify that this system will perform appropriatley.  If someone can shoot over a message I would greatly apreciate it.

RE: Static Pressure Loss in Flex Duct Systems

See SMACNA HVAC Systems Duct Design. The 1990 Issue page 14.8 Table 14-1 Duct Material Roughness Factor shows flexible duct to be classified "Rough". Page 14.9, Figure 14-3 Duct Friction Loss Correection Factors shows correction factor for "Rough" varies with velocity & diameter. Check if your office have a copy of the above SMACNA book.

Make sure you count elbows & bends. A 45° elbow is considered to have 0.6 X the pressure drop of a 90° elbow.

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