Foam Req'd for Diesel Generator Inside Building?

7/15/2024

The hot topic of AFFFs and PFOS. Where is the requirement stating foam must be used for fire protection for a diesel generator inside a building?

We're looking to eliminate the need for foam instead of replacing it with "fluorine" free foam.

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8 Comments

Dan Wilder

7/15/2024 08:51:58 am

A diesel generator itself may not require foam, the diesel fuel storage tank may. That falls into Chapter 57 of the IFC but as for a specific protection scheme, I am not aware of anything only allows one option. Lots of factors about the existing building, equipment, and storage would also need to be reviewed.

A previous discussion
https://www.meyerfire.com/daily/foam-design-criteria-for-diesel-storage-tank

Alican Kabatas link

7/15/2024 10:06:05 am

We always protect diesel fuel storage tanks with a wet pipe sprinkler system in Turkey and at abroad projects where we are the FLS consultant.

The main reason is that we do not expect a spill fire for diesel fuel. The flash point is more than 62°C, while the boiling temperature is about 200 to 300°C. The fuel is stored within the tank, and there is a full capacity dike wall or double-wall tank (which is safer than a dike wall).

The main purpose of the sprinkler system is to prevent excessive heating of the fuel storage tank if there is a fire within the generator room. If we have a spill, the diesel fuel is expected to be kept within the dike, and this limited surface fire can be controlled by the sprinkler system as well.

When we are trying to find a code reference for our engineering judgment, we use the following clauses:

NFPA 37 allows the usage of sprinkler systems for combustion engines and their support areas. Clause 11.4.1.
NFPA 37 provides sprinkler system design criteria. Clause 11.4.5. (I know this clause is pointing lubrication oils but I still use it.)

The sprinkler system is easier and simpler than the foam system, and it requires less periodic checks; i.e., simpler is better for safer operation. Therefore, we always prefer to provide a sprinkler system instead of foam, if possible.

Jack G

7/15/2024 11:21:19 am

First , determine which codes and standards apply and then how they apply.
Second, if this is E- deisel ( blended with ethanol for environmental concerns ) then this pushes it from a combustible to a flamable liquid.
The ifc has a daytank allowance of 660 gallons, then chapter 50 would force you to look at max allowed. It would then push you into IFC 56 and NFPA 30.
Last, discuss findings and solution with the AHJ.
Opinion.

Franck

7/15/2024 11:40:39 am

Emergency Power Diesel Generators are to be considered Extra Hazard Group 1 as per NFPA 13 (required density of 0.3/2500).

Best practice is to use High Temperature sprinklers with the recommended density (286°F)

Franck

7/15/2024 11:42:45 am

Extracts from NFPA 37 (no mention to provide foam in addition):

11.4.5.1
Automatic sprinkler systems shall be designed to provide a density of 12.2 mm/min (0.3 gpm/ft2) over the most remote 230 m2 (2500 ft2).

11.4.5.1.1
Sprinklers and spray nozzles shall be spaced at a 9 m2 (100 ft2) maximum area of coverage per sprinkler or spray nozzle.

11.4.5.1.2
Sprinkler and water spray system coverage shall be provided to all areas within the enclosure located within 6 m (20 ft) of the following:

(1) The engine
(2) The lubricating oil system
(3) The fuel system

11.4.5.2
Sprinklers and water spray nozzles shall not be directed at engine components that are susceptible to thermal shock or deformation.

A.11.4.5.1
Automatic sprinkler systems are considered to be effective in controlling lubricating oil fires. Sprinkler densities provided in this standard are based on Extra Hazard, Group 1 occupancy as defined in NFPA 13. Automatic sprinkler protection designed as local protection for the engine in many cases provides better protection than sprinkler protection installed only at the ceiling level, particularly in the case of pressurized lubricating oil fires.

Consideration should be given to providing local protection when the protected engine equipment is located in a high bay area. Delayed activation time or lack of water penetration could delay fire suppression from a ceiling system.

Local protection for engines can be accomplished using either a wet system or a single interlock preaction deluge system with heat detection. Detectors for actuation of a preaction system should be located above the engine and around the system piping.

For diesel engine installations, the system piping should loop the engine at the height of the cylinder heads.

Because of the tight radial clearances on combustion gas turbines and the potential for rubbing of rotating parts and increased damage, it is advisable to use great care if using a sprinkler or water spray suppression system. Water from a ceiling or spot protection system could effectively control a fire; however, gaseous suppression agents could be just as effective without the potential for equipment damage when the system activates.

Jack G

7/15/2024 11:56:42 am

If a room within a building I am assuming that it is enclosed with fire walls ,doors, assemblies of the proper fire rating.
I would look into that also.

Anthony

7/16/2024 08:18:10 am

To answer the question when is foam required for a generator, I don't think it is as others have mentioned an extra hazard system will suffice. Foam may be required due to the volume of fuel present. IFC ch57 has some "where a fire code official requires" clauses that would require an NFPA 11 system for larger class 1,2 and 3 tanks. The language is a little unrefined and I think that leads many code officials to err on the side of caution and require it.

Todd E Wyatt

7/16/2024 08:24:40 am

The scoping Code (e.g. IBC-2021) identifies where an automatic sprinkler system (ASPS) is required based on the Occupancy Classification(s) (OC) assigned to the building and/or “Specific Building Areas and Hazards”.

IBC-2021
Chapter 9 Fire Protection and Life Safety Systems
Section 903 Automatic Sprinkler Systems
903.2 Where Required
Approved automatic sprinkler systems in new buildings and structures shall be provided in the locations described in Sections 903.2.1 through 903.2.12.

Generator Rooms are exempted in buildings protected by a NFPA 13 ASPS system per 903.3.1.1.1 (3) :

IBC-2021
Chapter 9 Fire Protection and Life Safety Systems
Section 903 Automatic Sprinkler Systems
903.3 Installation Requirements
903.3.1 Standards
903.3.1.1 NFPA 13 Sprinkler Systems
903.3.1.1.1 Exempt Locations
Automatic sprinklers shall not be required in the following rooms or areas where such rooms or areas are protected with an approved automatic fire detection system in accordance with Section 907.2 that will respond to visible or invisible particles of combustion. Sprinklers shall not be omitted from a room merely because it is damp, of fire-resistance-rated construction or contains electrical equipment.
3. Generator and transformer rooms separated from the remainder of the building by walls and floor/ceiling or roof/ceiling assemblies having a fire-resistance rating of not less than 2 hours.

If the decision is to provide an ASPS in the Generator Room, a foam-extinguishing system (FES) is permitted as an Alternative Automatic Fire-Extinguishing Systems (AAFES) …

IBC-2021
Chapter 9 Fire Protection and Life Safety Systems
Section 904 Alternative Automatic Fire-Extinguishing Systems
904.7 Foam Systems
Foam-extinguishing systems shall be installed, maintained, periodically inspected and tested in accordance with NFPA 11 and NFPA 16 and their listing. Records of inspections and testing shall be maintained.

… although a FES is not the required ASPS for a Generator Room (unless the Building Official requires it for the above-ground tanks per IFC-2021 5704.2.9.2.1).

Foam Req'd for Diesel Generator Inside Building?

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