2 replies to this topic

[ashok.kumar]

Rim Vents are usually provided on the floating roofs of storage tanks to vent the vapour space below the rim seal.

• Though pumping-in & pumping out rates are not applicable for a roof already floating, it becomes applicable for a very short period before the floating roof starts to lift-off or rest-on its leg support.
  
• Is the ‘thermal in-breathing & out-breathing requirements’ as defined in API 2000 applicable for sizing rim vents? (API 650 11^th Edition Appendix-D clarifies that thermal breathing is not a criteria in sizing the bleeder vents on the deck. However the Code is silent about the requirements of design of rim-vents).
  
• Most of the Clients’ Specifications require to providing “Breather Valves” on rim vents.

Considering the above, Please advise the criteria usually used for deciding the sent points of these breather valves (for in-breathing & out-breathing) and for sizing these valves. Are there any Published Papers, Codes or Reference Books, defining the sizing criteria of Rim Vents ?
Ashok.

[fallah]

Ashok,

As far as i know, rim vent would be considered on a tank equipped with a rim seal system that can create a vapor pocket and only vents the pressure (no any action for vacuum) and its set point would usually be around 2-3 mbarg. You should specify the required rim vent via relevant data sheet and vendor will size/select the proper one to meet your requirement.

Fallah

[gegio1960]

The question of Ashok (and my question too) is also relevant to the criteria to establish the flowrate thru the vent.
Thanks.