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.


Floating roof emptying velocity

Floating roof emptying velocity

I've looked around a bit and can't find any clear guidance, rules of thumb or operational experience on what is a good number to use for a floating roof velocity, specifically for emptying.

The tank is planned to be 14m diam by 18 high. Nothing too special about the product or roof, not waxy, moderate temperature, SG about 0.75.

Maybe I'm concerned about something which isn't an issue, but I was under the impression that floating roofs of this size, (or maybe it's only for bigger ones?), couldn't or shouldn't rise and fall outside certain velocity limits.

we're looking at somewhere around the 0.7 metres per hour range normally but up to 1.5 m/hour occasionally.

I've seen 1" per minute mentioned as a "guide" before now which seems quite reasonable (1.5 m/hr)

I realize it might be vendor dependent, but we're in the prelim design phase at present, so no vendors to talk to / discuss things with.

Any guidance, especially with references or just experience would be gratefully appreciated. Thanks LI

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Floating roof emptying velocity

In my 49 years working floating roofs, the fastest I've watched them move is about 1 inch a second.
No harmful effects.
I think one inch a minute is way too slow.
If I had to draw a line in the sand, I'd go for 1 inch in 5 seconds, 12 inches or one foot an hour.

RE: Floating roof emptying velocity

IFRS. Many thanks for response. Just checking that you meant 1 foot per minute??


Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Floating roof emptying velocity

My math s*cks. Yes, 1 foot per minute

RE: Floating roof emptying velocity

Well, its depends on the input/outlet nozzles flow rates and the diameter of the tank as well ******

RE: Floating roof emptying velocity


My point is that we are looking at what outlet flow rate is "safe" and reasonable to determine nozzle sizes etc and one of the inputs to the decision is whether this is affected by any limitations on floating roof speed of descent. This tank is in design phase and whilst size is fixed, other parameters are not.

From IFRs response, it (roof vertical speed) doesn't appear to be a limitation, but if you have alternative information then please let me know.



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

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!


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