8 replies to this topic

[CPrabhakaran]

My task is to design fire water/ foam system for dikes crude oil tank farm consisting of 2 fixed roof tanks with 28ft dia and 21.5ft height. I want to determine following basedon NFPA.

1) Highest fire water demand calculation

2) Sprinkler/spray system for tanks,diked area and transfer pumps( no.of nozzles,spacing,spacing between water rings , flow per nozzle etc)

3) Foam system( surface/sub surface application, supplementary protection, foam requirement for diked area, foam line sizing etc)

4)All line sizing including rings, mains, risers, drains etc

5) numbers of supplementary fire water protection system for diked area and their capacities with spacing between hydrants/montors/hose lines

[asade]

1. You need to determine the firewater demand for each area or equipment or tank in the facility
2. After deternation of the individual firewater demand, you design your firewater facility based on the highest firewater demand
3. Based on NFPA 15, use 20.4 (L/min)/ m2 or 0.50 gpmft2 to determine the firewater requirement for each area or equipment by multiplying the design density with the Equipment surface area or plot area.
4. Base on your result, you designed your FW system to meet the FW demand for the duration of 1 hour
5. The number of monitors required would depend on your equipment layout
6. You need to consult NFPA 20, 15, 14, 16, etc. to have a broad picture of your design.

I hope my little info would assist you in kickstarting your design.

 

Stay cool.

[ankur2061]

Prabahakaran,

 

For firewater demand calculations for tanks / vessels refer the link below:

 

http://www.cheresour...-tanks-vessels/

 

For foam demand calculations refer the following link:

 

http://www.cheresour...d-calculations/

 

For detailed guidelines for firewater system design as "Asade" has mentioned you need to refer NFPA 15 & 20. For guidelines for firefighting foam refer NFPA 11.

 

If this system is being designed for installation in India then refer the standard OISD-STD-117 (Standard for "Fire Protection Facilities for Petroleum Depots, Termainals, Pipeline Installations, and Lube Oil Installations")

 

Regards,

Ankur.

Edited by ankur2061, 07 July 2014 - 06:07 AM.

[mosayef]

hi all,

 

i have read ankur's post above about the fire water demand calculation. in ankur's post, the fire water demand is calculated based on the NFPA 15 which is for water spray or sprinkle demand. how if i want to estimate the water demand for fire hydrant / fire monitor ? is it just th same with NFPA 15 or should i follow another procedure ?  i have read NFPA 13 and 14 but i can't find the water demand per area needed (gpm/ft2). please, i need your help

[breizh]

mosayef ,

You should consider to talk to your fire brigade , they should be able to support you .

 

Hope this helps

Breizh

[ankur2061]

mosayef,

 

You need to refer NFPA 24: Standard for the Installation of Private Fire Service Mains and Their Appurtenances

 

Regards,

Ankur

[mosayef]

dear all,

 

i want to ask about fire water demand in the plant.. as far as i know, to calculate fire water demand we need to devide the plant to several zones. let say if i have 4 reciprocating compressors (3 on line and 1 back up compressor) in a zone. 

 

do i need to sum up all of the 4 compressors to calculate fire water demand ? or i just take 3 on line compressors ? or i just need to consider only 1 reciprocating compressor (assume the fire will not affect other compressors if one of them is in fire) ?

Edited by mosayef, 26 August 2015 - 10:33 PM.

[Narayanan.u]

In one zone you need to consider the cumulative demand for all equipment. 

[mosayef]

if i calculate this in cumulative. i should install fire water pump with rated capacity around 1250 gpm. 

is it ok if i supply this1250 gpm in one hydrant only if fire occured ?

even though the discharge pressure at hydrant is set 100 psig. but 1250 gpm is big enough for hydrant 4,5"

 

please give me  information about this