Ask the Expert, Chemicals, Emergency Preparedness and Response, Q&A

Flammable Substance Threshold

Q. Would the risk management plan (RMP) flammable substance exemption include warehouses? We will store cans of foam containing isobutane. Will the RMP regulations apply?

A. Isobutane is on the list of regulated flammable substances under 40 CFR 68.130, and therefore has a threshold of 10,000 lbs.

The risk management plan (RMP) exemption under 40 CFR 68.126 for flammable substances only applies when the flammable substances are used as a fuel or held for sale as a fuel at a retail facility. Per 40 CFR 68.3, a retail facility is defined as a stationary source at which more than one-half of the income is obtained from direct sales to end users or at which more than one-half of the fuel sold, by volume, is sold through a cylinder exchange program.

Based on the information provided in the question, the isobutane is not used as a fuel so the process/facility is potentially subject to the RMP requirements.

However, on page 1-13 of Chapter 1: General Applicability of EPA’s RMP Guidance for Warehouses, the Agency offers this Q&A which you should consider as it might correlate to your situation:


Q. We store consumer products that use butane as a propellant. Each product only has a few ounces of butane. Do we need to estimate the total amount of butane in all the products?

A. Listed flammable substances are excluded from coverage only if they are used as a fuel. In this case, butane is not being used as a fuel (i.e., it is not being burned to produce heat or power). As long as the butane is released from the product in normal use, you must estimate the amount of the regulated substance present. If the butane is mixed with the product, you should determine whether the product itself meets the criteria for NFPA 4. If the mixture does not meet the NFPA 4 criteria, the butane in the mixture is not counted toward the threshold.

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