Chemical Storage Compatibility Calculator
Assess chemical storage compatibility and segregation requirements based on hazard ratings for acids, bases, oxidizers, flammables, and toxics.
About this calculator
This calculator screens for the classic dangerous storage combinations rather than scoring any single chemical's hazard in isolation — its scoring formula is built entirely from products of hazard ratings, so risk only appears when two incompatible hazard classes are both present at the same time. Acid and base ratings multiply together (a violent neutralization and heat-release risk), oxidizer and flammable ratings multiply together and are weighted most heavily (the classic fuel-plus-oxidizer fire and explosion pairing), and acid and oxidizer ratings multiply together at a smaller weight (a known source of toxic fume generation). Toxicity contributes its own flat score independent of any pairing, since a highly toxic material is a storage and handling concern on its own regardless of what else is nearby.
Because every hazard interaction term is a product, a chemical that is rated highly on only one axis — say, strongly flammable but rated zero on acid, base, oxidizer, and toxic — contributes nothing to the paired-hazard score, even though it may still deserve real safety precautions the calculator's storage-class figure alone partially captures. The compatibility score, segregation level, and storage class are simplified planning heuristics meant to flag combinations worth investigating further, not a substitute for consulting actual Safety Data Sheets, NFPA 400 segregation tables, or a qualified EHS professional before finalizing a real storage layout.
Inputs
Results
Compatibility Score
2 / 100
Segregation Level
1 (1-4)
How to Use This Calculator
- Rate the Acid hazard of the chemical on a 0–3 scale: 0 = none, 1 = mild acid, 2 = moderate acid, 3 = strong acid (e.g., sulfuric or hydrochloric).
- Rate the Base/Alkali hazard: 0 = none, 1 = mild, 2 = moderate, 3 = strong base (e.g., sodium hydroxide).
- Rate the Oxidizer hazard: 0 = none, 1 = mild, 2 = moderate, 3 = strong oxidizer (e.g., nitric acid, hydrogen peroxide).
- Rate Flammability: 0 = non-flammable, 1 = combustible, 2 = flammable, 3 = highly flammable (e.g., solvents, fuels).
- Rate Toxicity: 0 = non-toxic, 1 = slightly toxic, 2 = toxic, 3 = highly toxic (e.g., cyanides, chlorine).
- Review the Compatibility Score out of 100, the Segregation Level (1–4), and Storage Class to determine if chemicals can share a storage area or require physical separation per NFPA 400 and OSHA 1910.106.
How the result changes with Toxic Rating
| Toxic Rating | Compatibility Score | Segregation Level |
|---|---|---|
| 0.5 | 1 / 100 | 1 (1-4) |
| 0.75 | 2 / 100 | 1 (1-4) |
| 1.5 | 3 / 100 | 1 (1-4) |
| 2.5 | 6 / 100 | 1 (1-4) |
What each input means
- Acid Rating
- Acid hazard rating: 0 = none, 1 = mild, 2 = moderate, 3 = strong acid.
- Base Rating
- Base/alkali hazard rating: 0 = none, 1 = mild, 2 = moderate, 3 = strong base.
- Oxidizer Rating
- Oxidizer hazard rating: 0 = none, 1 = mild, 2 = moderate, 3 = strong oxidizer.
- Flammable Rating
- Flammability rating: 0 = non-flammable, 1 = combustible, 2 = flammable, 3 = highly flammable.
- Toxic Rating
- Toxicity rating: 0 = non-toxic, 1 = slightly toxic, 2 = toxic, 3 = highly toxic.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersAcid Rating = 1, Base Rating = 0, Oxidizer Rating = 0, Flammable Rating = 2 = 5 input(s) provided
- Calculate Compatibility ScoreCompatibility Score2 = 2
- Calculate Segregation Level1 = 1
- Calculate Storage ClassStorage Class2 = 2
- Calculate Risk ScoreRisk Score0.2 = 0.2
Engine last updated . Checked against 3 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why did raising one hazard rating not change my compatibility score at all?
Every interaction term in this calculator's scoring is a product of two hazard ratings — acid times base, oxidizer times flammable, acid times oxidizer — so if the rating you raised has no counterpart hazard present (its multiplying partner is still rated zero), that interaction term stays at zero regardless of how high the rating you changed is. Only the flat toxicity term and pairs where both hazards are nonzero move the score.
Why is the oxidizer-flammable combination weighted higher than acid-base?
An oxidizer accelerates combustion by supplying the oxygen a fire needs, so storing a strong oxidizer next to a highly flammable material creates one of the most dangerous storage scenarios in industrial chemical handling — a fire that starts small can escalate rapidly with an oxidizer feeding it. Acid-base contact is genuinely hazardous too, but typically produces heat and possibly violent neutralization rather than the fire-acceleration risk oxidizer-flammable pairings carry.
Does a low compatibility score mean it's safe to store chemicals together with no precautions?
No — a low score means this simplified model didn't detect a strong pairwise interaction between the specific hazard classes rated here, but it doesn't verify actual chemical compatibility, physical storage conditions, ventilation, spill containment, or any hazard this calculator doesn't model. Always confirm real compatibility using the chemicals' actual Safety Data Sheets before finalizing a storage plan.
What's the practical difference between the segregation level and the storage class outputs?
Segregation level reflects how far apart the two (or more) chemicals need to be kept — from sharing the same area at level 1 up to requiring separate buildings at level 4 — based on the interaction score between their hazard classes. Storage class is a simpler single-chemical rating based on the single highest hazard rating you entered, independent of any pairing, giving a rough sense of how hazardous the worst individual material in the mix is on its own.
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