How Much Engine Oil Stored in an OH2 Building?

10/13/2023

How much engine oil can be stored in a building with an Ordinary Hazard Group 2 (OH2) sprinkler system?

We're working on a repair garage and NFPA 13 (2019) classifies repair garages as OH2 in the appendix. It seems reasonable that some amount of engine oil would be allowed to be stored. However, the NFPA 13 definition of OH2 doesn't allow for flammable/combustible liquids, but EH1 and EH2 allows for some unspecified amount of flammable/combustible liquids.

NFPA 13 section 26.2.1 states that sprinkler system discharge criteria for the protection of flammable and combustible liquids shall comply with NFPA 30. NFPA 30 (2021) table 10.7.1 allows for unlimited IIIB liquids to be stored in mercantile occupancies with an OH2 sprinkler system.

Can this mercantile section be applied to a storage occupancy?

Thanks in advance.

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5 Comments

Pete H

10/13/2023 06:51:30 am

If you're in storage, you're governed by NFPA 30 Chapter 16, not Chapter 10, as you're no longer a mercantile occupancy.

Now it depends on how it's stored and how much is stored.

There is guidance on IIIB liquids in the figures and tables (Figures 16.4.1a-c and Tables 16.5.2.1-16.5.2.10)

Dan Wilder

10/13/2023 09:14:10 am

By definition - No, these are definable and separate areas.

First, need to look at the ICC (or whatever your local adoption for Building Codes are). Quick glance and there are likely some additional restrictions/allowances I'm not applying and not sure what the building construction is.

ICC 2021 - Chapter 3 - Repair Garages are defined as S-1 - Motor vehicle repair garages complying with the maximum allowable quantities of hazardous materials specified in Table 307.1(1) (see Section 406.8). If they have attached public accessible retail areas which is defined as Group M (with their own MAQ per Table 414.2.5(2), then it's a mixed-use occupancy and needs to comply with Chapter 5.

Table 307.1(1) - The MAQ for Liquids looks to be 30 Gal of Class 1A & 120 Gal of Class 1B & 1C. There are allowances to increase this by 100% for sprinklered buildings, and another 100% for keeping under the max amount within each "Control Area".

Control areas are defined by fire rated separations as defined/required so they could store barrels in a room, transfer that oil to other equipment that is brought out into the repair area. There's a reason they leave their used oil outside under a small lean to/canopy structure.

Anthony

10/13/2023 09:58:25 am

I 100% agree with Pete and Dan here. You can't apply mercantile code to storage applications. There are a bunch of assumptions made by the code based on the occupancy of an area.

This is what my old mentor would say "falls into the ghostbuster's don't cross the streams rules." Stay on your code path.

Casey Milhorn

10/13/2023 11:38:24 am

I also agree with Dan and Pete's assessment and are a lot better than me at the code side. From a more practical fire sprinkler contractor/designer perspective, remember that NFPA 13 classification is only part of it, and in this case flammable/combustible storage cabinets might be part of the overall solution along with other possibilities. I know as a sprinkler designer, sometimes I have blinders on and I think we need to be the problem solver for everything by just upping the hazard. It's good to remember we are just part of the overall fire protection scheme and that it's important that a competent FPE or PE be involved.

Glenn Berger

10/13/2023 12:26:44 pm

Take a look at the specific flash point(s) of the engine oil that may be used at this location. Some motor oils have a very high flash point and might be able to be classified as a Class IIIB combustible liquid.

How Much Engine Oil Stored in an OH2 Building?

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