Duration for Secondary Containment in FM?

7/27/2026

I am working with a company storing Class IIIB liquids in plastic tanks. Tanks range in size from 2000, 3000, to 6100 gallons.

We struggled to find a design that works in NFPA and therefore went with a .40/3,000 from FM DS 7-32; however, now we do not know what to do with the containment requirements.

What should the containment duration be?

Since they are plastic tanks, I have assumed they would all fail and would essentially need containment around each tank?

Thanks in advance.

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4 Comments

Jesse

7/27/2026 08:25:49 am

I think you're asking about duration of sprinkler discharge as it impacts the secondary containment, so I'm guessing this is indoors and rain isn't a factor.

The short answerer is 20 minutes I think in most cases. But, and this is a big but, some insurers want more. I know the property carriers I've done work for wanted 150% of the combined capacity of the storage vessels.

Anthony

7/27/2026 09:22:01 am

I'll unhelpfully add here that NFPA 30 runs you in circles for interior tank storage. Very difficult to VE anything here with out oodles of experience.

Felipe

7/27/2026 10:39:04 am

You can reference IFC Section 5004 - Storage

5004.2.2.3 for Indoor design and 5004.2.2.4 for Outdoor design.

I was not able to find the data sheet reference for FM, but I worked on a similar project and the FM report had me account for a 60 minute duration.

FMDS 7-83 and FMDS 7-88 provide information for drainage/containment/storage of ignitable liquids.

Hopefully that helps.

Dan

7/28/2026 01:35:14 am

FM 7-29, InterimRevisionApril2026, Table 2.2.2.1.B. Drainage and Containment Requirements for Liquid Storage in Plastic, Glass or Other Combustible Containers in Cutoff Rooms/Buildings (continued):
≥200°F (93°C): >6.5 gal (25 L: 1. Provide emergency drainage and containment arranged to prevent spilled liquid and actual sprinkler discharge (Note 1) from spreading to other building areas not
protected for an ignitable liquid fire hazard for 30 minutes. Arrange the drains to subdivide the room into the smallest practical drainage areas but no larger than 5000
ft 2 (465 m2). Provide no less than 3 in. (76 mm) of containment across all interior openings. All containers in the cutoff room are expected to fail.
Or
2. Provide containment and a special protection system as per this data sheet. Design the containment to keep spilled liquid and actual sprinkler discharge (Note 1) plus
special protection system discharge from spreading to other building areas not protected for an ignitable liquid fire hazard for 20 minutes. Provide no less than 3 in.
(76 mm) of containment across all interior openings.
Or
3. For composite IBC storage protected in accordance with Table 2.4.6.1, provide emergency drainage and containment or containment alone arranged to prevent spilled
liquid and actual sprinkler discharge (Note 1) from spreading to other building areas not protected for an ignitable liquid fire hazard for 30 minutes. Provide no less
than 3 in. (76 mm) of containment across all interior opening

Hope this helps.

PS: Ceiling protection: you may want to look at this, same data sheet: 2.4.6Composite,All-Plastic,andBag-in-BoxIBCStorageofLiquidswithaFlashPointAtorAbove
200°F(93°C)orAlcohol inRacksorPalletizedStorageofPropyleneGlycol,EthyleneGlycol,
Glycerin,NMP,orDMSO

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Duration for Secondary Containment in FM?

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