Floating roof emptying velocity 1

[LittleInch]

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

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[IFRs]

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.

 

[LittleInch]

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




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[IFRs]

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

 

[Nawfal]

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

 

[LittleInch]

Nawfal,

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.

Thanks

LI

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