Cooling Rings to Fuel Oil Tanks

[noz1]

Hi All,

Could someone please tell me what the "industry standard" is for Deluge Cooling Rings for exposure protection?

The NFPA is not clear on this issue and I do not want to over specify, do I need to allow for 3.7m run down between rings ? Or can I just put a single ring at the top of the Tank?

The Tank I have is 23m diameter with a height of 19m so at a Density of 10.2mm/min/sq m you can see I would have a large flow from a single ring! Your comments would be appreciated!

Cheers
D

 

[DavidCR]

I´ve been looking for info on that and I didn´t found much so I don´t have a good response, but I can mention some points:

-API 2030 mentions some basic points, for example mentions that it is used for the upper 3.7 to 7.4 meters of the shell (since the shell that is in contact with fuel is not subject of risk of dangerous heating). If the tank is most of the time full or half-full it would apply.

-API 2030 and NFPA 15 coincides on the 4.1 L/min/m2 (0.1 gpm/ft2) value for exposure protection.

-Depending on the type of fuel and tank NFPA 30 includes a list where the exposure protection is mentioned (look for the safe distances from tank walls, I don´t remember where it is exactly, chapter 4 I guess).

-API 2021A is a study where it is mentioned that fixed spray has not been a big deal in actual fires.

-Viking (

http://www.vikingcorp.com)

has information on design of deluge systems that may apply.

-Most people I´ve asked told me that the requirement is mentioned in many company standards, in british petroleum standards, but since there is not a well based proof that it has been an important issue on actual fires, it is not strongly endorsed.

-I´d recomend to consider spraying when you have class I liquid and important real exposure risk, if it is a II or III fuels it is a difficult money decisión and many variables should be considered.

-If the risk is high consider other fire protection means, like fixed-foam, monitors, tough tank fire fighters.

-Semi-rings or half-rings are recomended to save water and mantain system pressure for other demands in an emergency, you only spray the sides of the shell that are exposed to fire.

Hope this helps.