Begin with the basics: why heat balance, inventory and change are what matter.
Learn to spot a high-hazard process, then test yourself.
Go straight to the thermal-hazard sequence.
Drag the sliders and watch the Stoessel criticality class change.
Work through them in order: each lesson builds on the one before. Mark lessons as completed to track your progress (saved in this browser only).
Key terms, the runaway problem, and the functional groups that warn you a molecule can release energy.
2A screening checklist for reactivity, fire & explosion, toxicity and special reactions, with an interactive version.
3What each instrument measures, when to use it, and how to read a DSC thermogram.
4Heat of reaction, ΔTad, accumulation, cooling capacity, MTSR and TMRad: the cooling-failure scenario step by step.
5Four temperatures, five classes, and the safety measures that go with each.
6Why a safe lab reaction can be unsafe in the plant, and which process changes need new safety data.
7Explosion pentagon, MIE, Kst and St classes, resistivity, and the tests that characterise a powder.
8Relief scenarios, illustrative vapour, liquid and fire-case screening calculations, and why runaway relief is two-phase.
9Source terms, dispersion, AEGL and LFL zones, pool fires, and emergency response.
All the calculators and simulations on one page. All are educational screening tools: results depend on the stated assumptions and do not replace a qualified assessment.
| Tool | Purpose | Where |
|---|---|---|
| Stoessel slider | Feel how the four temperatures set the class | Hub |
| Stoessel class calculator | Thermal criticality screening from your data | Lesson 5 |
| High-hazard checklist | Early hazard screening of a new process | Lesson 2 |
| Dosing time vs cooling | Shortest dosing time the cooling can handle | Lesson 4 |
| TMRad and TD24 | Decomposition clock from one measurement | Lesson 4 |
| Relief screening | Illustrative vapour, fire-case and liquid relief calculations | Lesson 8 |
| Dust ignition (MIE) | MIE and powder resistivity: what they mean in the plant | Lesson 7 |
| Safety devices explained | How PSVs, rupture discs, SIS interlocks and flame arrestors work | Equipment |
| What-If Leak | Release consequence visualisation in the 3D plant | Plant tour |
| Runaway! challenge | Reactive-hazard training game | Game |
| Troubleshooter | Scenario-based plant diagnosis | Game |
Four plant-style problems with full solutions: shortest dosing time, reading DSC results, TMRad and TD24 from ARC data, and fire-case relief sizing.
Open the exercisesWhat went wrong, why, and what to check in your own plant.
A catastrophic methyl isocyanate release from a storage tank at a pesticide plant.
Safeguards out of service · inventory · sitingA temporary bypass pipe failed and released hot cyclohexane: vapour cloud explosion.
Management of changeCooling failed during a batch, the reaction ran away and the reactor exploded.
Reactive hazards · cooling · reliefA petrol tank was overfilled because both level protections failed: a huge vapour cloud explosion.
Overfill protection · containmentStyrene in a storage tank heated up and polymerised during the lockdown, releasing vapour over the town.
Reactive storage · restart after shutdownPut it into practice.
Learn MTSR, MTT and TD24, take a quick quiz, then design four reactions so a cooling failure cannot turn into a runaway.
Play →⚠️A fast arcade game: spot hazards, read live process trends and decide what needs attention first.
Play →🧭Model a chemical leak or fire in the 3D plant: toxic and flammable zones, pool fires and a full emergency response.
Open the plant →🎮Diagnose plant problems from real-world-style scenarios.
Play →For training and awareness. Numbers in lessons and exercises are illustrative; real processes need measured data and a qualified process safety assessment.