determining the placement / location of fire hydrants in tanks farm

[kald]

After conducting a FERA (Fire and Explosion Risk Assessment) and QRA (Quantitative Risk Assessment) study, what is the the recommended risk level / radiation contour to placement / install of fire hydrants. and can we install fire hydrants within the 10^-4 (or 0.0001) risk level contour (ALARP Zone) or within the 12.5 kW/m2 radiation contour. what is the precaution in this case

 

[mk3223]

IMO, you need a Fire Protection Engineer who is familiar with the required regulations in your location and may provide you a protection plan for the facility based on the the studies have done.

 

[LittleInch]

Hydrants are not the same as monitors which can be remotely operated or work on a fixed pattern.

Hydrants just supply water to a hose. The hose can be quite long so anyone connecting to it can be closer to the fire than the hydrant.

Just have enough of them and let the fire dept worry about how to use them.

Our just ask them where they want them.

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

 

[MJCronin]

kald:

https://cityofgp.com/sites/default/files/docs/inspections/fire_flow_calculation_sheet_and_guide.pdf

This document contains some guidance: (but, as stated by LittleInch, it may not pertain to your situation ..)

"The maximum recommended spacing of hydrants in commercial, industrial, institutional and multi-family residential areas is 90 metres; in single family residential areas 180 metres is recommended"

I agree that you need an experienced Fire Protection Engineer, familiar with all of the required regulations for your plant and can provide you with a detailed protection plan.. !!!

Section 7.2 of NFPA-24 might help too ..

https://www.modares.ac.ir/uploads/Shr.Technical.Rar.115.pdf

MJCronin
Sr. Process Engineer

 

[ProSafPlant1]

A comparison of hydrant spacing guidelines in the attached list f

or interest.

 

[kald]

Thank you very much for your attempt to assist, although I might still be struggling to clarify my question.

Based on the findings of the Fire and Explosion Risk Assessment (FERA) study, different levels of radiation contours are associated with specific actions and considerations:

4.7 kW/m2 Radiation Contour: Chance of fatality for instant exposure. Pain threshold in less than 2s.

12.5 kW/m2 Radiation Contour: Typical fatality threshold, for normally clothed people, resulting in third degree burns after 30 seconds exposure. Significant chance of fatality for extended exposure. Pain threshold reached in 3-4s.

37.5 kW/m2 Radiation Contour: Chance of fatality for instant exposure. Pain threshold in less than 2s.


To ensure the effectiveness of fire-fighting systems and to prevent the escalation of fire hazards, a reference radiation contour of 12.5 kW/m2 is commonly employed for design purposes. Critical fire-fighting equipment must be positioned outside this contour to optimize their performance. Furthermore, meticulous attention should be given to the 4.7 kW/m2 contour, aiding in determining the strategic placement of fire-fighting devices requiring swift human intervention within 2-3 minutes. It's essential to note that within the 6.3 kW/m2 contour, specific precautions are warranted. In these areas, firefighting equipment's positioning might demand personnel exposure. Adequately attired with safety gear such as hard hats, long-sleeved shirts, full-length pants, and appropriate footwear, personnel may need to engage in emergency actions lasting up to 30 seconds.

the question Is it feasible to place fire hydrants within the ALARP Zone (10^-4 or 0.0001 risk level contour) or within the 12.5 kW/m2 radiation contour? Additionally, what precautions should be taken into consideration in such a scenario?

 

[LCREP]

Kald,

Have you contacted the property insurance carrier for input? I was on the insurance side and provided our written insurance requirements to the fire protection engineer for the project all the time. We reviewed the fire protection plans and provided a written letter with our comments based on our requirements.

The underwriter, the person determining how much premiums they will pay always wanted our input. Given the size and $$ at risk you may have several insurance carriers providing coverage. But the lead insurance carrier providing the 1st 10-15% of $1 of coverage usually speaks for all. Sometimes the company will self insure for the 1st xxx millions but in the background insurance companies are involved. Many times the site would comply with local code requirements but not our insurance requirements. Insurance requirements are based on our loss experience with the occupancy and minimum underwriting requirements.

If the insurance carrier is Factory Mutual(FM) they have very specific requirements based on their Data Sheets. See who the FM “Account Engineer” is for the project.

It maybe worth a call.

Tom

 

[kald]

thank you Tom and I appreciate you sharing your experience in insurance .

 

[LittleInch]

kald,

Your post has the same pain threshold for 4.5kw/m2 and 37??

Anyway I think you're not looking at this correctly. Unless you only have one tank, the general assumption used is that only one tank will catch fire at any one time. The issue is you don't know which one.

So yes you can lay out the contours, but if tank 1 is on fire, there is no reason why a hydrant much closer to tank 3 or tank 4 can't be used. So that's why they are simply spread out every xxm so that wherever the fire is, the fire fighters can find a hydrant fairly close but not where they are themselves in danger and then run hoses out as they require.

It all depends on your philosophies and guides. There was another of YOUR posts recently which had similar questions about tank spacing. That gave you some answers no?

NFPA and some companies just work on the principle that all you really need to do is enough to allow everyone to escape before letting the tank farm burn down. Especially if you're in the middle on no where and have no decent water supply. This makes for a compact tank farm using less space than if you spread it all out on the basis that one fire would not impact the other tanks. insurance companies might like a much bigger spacing, but then it depends if you have the space as it costs a lot more.

Most fire systems also just look at preventing escalation as actively extinguishing the fire requires biblical amounts of water and foam. Just do some research into Buncefield....

So I don't think there is a simple answer to your question unless as I said, you only have one piece of equipment which can catch fire. Most sites have several so just spread the hydrants around and let the fire fighters use whichever they want to deal with the item on fire.

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