Oil Fire on Crushed Stone

[owg]

We have a client who is considering surrounding electrical transformers with crushed stone. The stone would be on top of a liner to contain a spill. Transformer incidents can include explosion and fire with burning transformer oil escaping to the surrounding area. The question is will the fire damage the liner under the stone. Has anyone seen any data, guidelines or methodology on this subject? We will discuss other more conventional containment options with the client.

HAZOP at

http://www.curryhydrocarbons.ca

 

[DTR]

Crushed stone within Transformer Pens is very common, I have been told that the crushed stone helps prevent any oil spills from "pooling" thus reducing the risk of large spill fires.

Because the stone is non absorbing, the Deluge System protecting the Transformer should also spray the floor at a Density of at least 6.1 litres per minute per square metre(SEE NFPA 15) therefore your membrane below should be ok.

 

[owg]

Thanks for that helpful comment.

HAZOP at

http://www.curryhydrocarbons.ca

 

[DavidCR]

I work for an electric facility and a system like the described has been adopted by our civil engineers from a japaneese old design thinking primarily on polution control of a possible spill.

The underground dike filled with stone has a drainage and pipe at the botom that leads to a concrete chamber located some meters apart, this chamber would work as a simple oil separator or trap in case of a spill (I´m sorry, it´s hard to describe this chamber with out a drawing, but it´s basically an oil trap working by gravity). In case of a big spill the chamber must be trated and pumped out to a proper separator, but at least part of the oil will be far away from the transformer until proper treatment.

Recently our company is going more aware of fire protection issues and we are not clear on this type of stone dike on the fire protection aspect.

Appart from this we´ve seen installations with an external concrete dike (with no stone dike) sorrounding the transformer, that has drainage outlets with valves that let the user direct the spill to an oil separator. This type of dike is more "clean" but an oil spill will be under the risk of a pool fire.

I have wondered about this, and I want to share some points specting more people help in this "post":

-Does the stone dike have to have the capacity for the oil spill plus the fire water following NFPA 15? (I wonder about the real volume capacity considering the stone volume).
-Is it used to have external dike, surrounding the stone dike?
-Does the stone really help to reduce the fire risk compared to an open pool fire?
-Is there a standard or known criteria that endorses the stone dike or more explanations on the fire protection aspect?
-Within the usage, the stone dike will be filled with little oil spills, dust, debris, etc., and in my opinion it will be difficult to predict how the stone dike will really work when needed in a big spill or fire.