×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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

Air Make Up unit with steam - design

Air Make Up unit with steam - design

Air Make Up unit with steam - design

(OP)
I have a requirement of an outdoor Air Make Up unit. Air capacity: 11,000 cfm. Location Toronto: Ontario. Room is does not have human unoccupancy (Indoor Temp: 65 Farenheit). I am exhausting all the air with negative pressure in this mechanical room. Medium pressure steam (50-100 psi) is available at this floor. Therefore its availability dictates the use of a steam coil in the unit.

I have a few questions in this regards:

Can I place the unit outside where it can be as cold as -30 degree centigrades?

How much steam pressure is good enough and how do I size my unit/coil?

RE: Air Make Up unit with steam - design

Coils like this tend to freeze in the spring/fall, rather than in the dead of winter. The available supply pressure of the steam is not really an issue as far as freezing the coil at very low outdoor temperatures is concerned. The temperature control valve on the steam supply will throttle-in as the air temperature approaches it's set-point. Even though this is not a pressure reducing valve, the effect is the same. If you have any backpressure at all in the condensate system, you  lose the pressure differential across the trap, and condensate backs up into the steam coil. It can freeze and split the coil in only a few minutes. You also require a vacuum breaker on the steam side. When the TCV closes, the steam in the coil collapses into a vacuum. Now now condensate can't drain, even by gravity.

The main thing is to drain the coil of condensate under all operating conditions, especially low load, when the outside air is near the freezing point. During very cold weather, the steam valve tends to be open to meet the demand, so there's always pressure to keep the condensate flowing. The coil needs to have a gravity drain to a vented receiver for the condensate, and a vacuum breaker.

Spirax Sarco's main office in Canada is in Toronto. I'm sure that someone there would be happy to get you a copy of "Hook-Ups", which has (among many other things) specific information on installations exactly like yours. A coil  manufacturer would be happy to make a recommendendation about the actual coil itself.

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


Resources

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