NFPA reference for foam concentration percentage 1

[ZDR1985]

Hi to all,

I would like to know if there is any international code like NFPA that defines foam concentration application. I have seen in NFPA 16 foam concentration percentages such as 1%, 3%, and 6%. How do I determine which concentration percentage shall I use for a certain application?

Thanks!

 

[LCREP]

Determine the product to be protected, alcohol, or hydrocarbon and or both. Then contact foam manufactures to determine what % of foam will extinguish the product. If this does not make sense contact a fire protection professional.

 

[Woodrow57]

As indicated the percentages are provided by the manufacturer and I have used the same foam manufacturer on two different projects, but both were flammable liquids, one in a 3% and the other in a 6% solution. One good reason for using one over another is the %-age that requires the least amount of stored foam (less foam to buy smaller foam bladder tank). Most special hazard companies are pleased to assist you as they recognize their help may elicit a recommendation for their product. There are LOTS less foam solution manufacturers today than there were 10~20 years ago. Another issue is the cost of the installed equipment, some foam installations require deluge equipment in the foam lines, others use hydraulically actuated ball valves, the ball valve is a much less costly design.

PW located in the heart of America-
Fire sprinkler contracting since 1978
NICET and ICC certified

 

[DavidCR]

Manufacturers are interested in developing an effective foam with low concentration (like 1%) as a way to sell a better product that is generally more expensive but may help you to save money in other things. Most of the foams work on 3%, but you are tempted to spend some money in a bettter foam that works on 1% and you save lot of money in equipoment. For a fixed system based on monitors if you use a low conc. foam you save a lot of money on bladder tanks, quantity of foam on reserve, etc. but it has to be a really good foam with good proportioning equipment.

A fire fighter knows that having a foam with the ability to work fine with 1%-3%-6% gives the option to choose a better performance for different fire scenarios. For example for a wild fire foam may work fine with a concentration of 1%, just to be used as a wetting agent and save foam. For a fire in a small dike with gasoline, using 6% with give you a thick foam that will last better. Of course the manufacturer has to certify with tests that the foam will work fine in specific cases.

 

[stookeyfpe]

Before you start selecting aqueous film forming foam (AFFF), which is it's technical definition, you better understand the hazards and chemistry of the liquid. A liquid is flammable may be miscible or inmiscible in water, which is a major factor in foam selection. The hydrocarbon may be mixed with other constituents. For example acetic acid is classified as a Class II combustible liquid and Corrosive liquid. Most organic peroxides will contain a flammable liquid which has been chemically bonded to oxygen and may contain a different flammable hydrocarbon to act as as either a diluent or stabilizer. In these cases AFFF or AFFF-ATC may not be appropriate for the hazard.

Packaging is another major component of the hazard assessment. See NFPA 30 Chapter 16 for the various decision trees and you will find that the container's material of construction and it's pressure relieving design (or lack of) will dictate the required fire protection.

Seek professional engineering assistance if you cannot perform this hazard analysis.