CSB Investigation — Explosion
Airgas Facility Fatal Explosion
Airgas Inc.
📍 Cantonment, FL
Incident Date: August 28, 2016  |  CSB Report Released: February 2017
1
Fatalities
Several
Injuries
7
CSB Recommendations
Nitrous Oxide
Chemical / Hazard
📋 Incident Summary

On August 28, 2016, an explosion killed one worker at the Airgas nitrous oxide (N2O) production facility in Cantonment, Florida. The incident occurred during the loading of a nitrous oxide trailer truck. A pump used to transfer liquid N2O overheated the gas above its safe operating limits, most likely initiating a nitrous oxide decomposition reaction that propagated from the pump into the trailer, causing the explosion.

Nitrous oxide, though commonly associated with medical and food applications, is a powerful oxidizer that can undergo exothermic decomposition when heated above its decomposition threshold, especially under confinement. The pump used for N2O trailer loading was a known point of concern — industry guidance had previously noted the risk of pump-induced overheating — but Airgas did not evaluate safer pumpless loading alternatives before installing and operating the pump.

The CSB found that Airgas had no effective process safety management system for its N2O operations. No PHA had been performed on the trailer loading system. No MOC review was conducted when the pump was installed. The CSB recommended that Airgas implement PSM for N2O operations and that regulatory agencies develop specific safety standards for N2O production facilities.

🔎 Key Findings
Finding 1
Pump Overheated N2O Above Decomposition Threshold
The N2O trailer loading pump heated liquid N2O above safe operating limits, initiating a decomposition reaction. Pump-induced N2O overheating is a recognized hazard that Airgas did not evaluate before installing the pump.
Finding 2
No PSM System for N2O Operations
Airgas had no formal process safety management system for its N2O production and loading operations. No PHA, no MOC program, and no formal mechanical integrity program existed.
Finding 3
No MOC Review for Pump Installation
When the pump was installed in the N2O trailer loading system, no management of change review was conducted to evaluate the new hazard introduced by pump-induced N2O heating.
Finding 4
Safer Pumpless Loading Alternatives Not Evaluated
Airgas did not evaluate alternative N2O loading methods — such as pressure-differential loading without a pump — that would eliminate the pump as a heat source and decomposition initiation risk.
Finding 5
N2O Below OSHA PSM Threshold — Regulatory Gap
Nitrous oxide falls below the OSHA PSM threshold quantity at most production facilities, exempting N2O operations from mandatory PSM requirements despite significant process hazards.
Finding 6
N2O Decomposition Hazard Underappreciated Industry-Wide
N2O decomposition hazards are well-documented in literature but not consistently recognized across all N2O production, distribution, and end-use facilities.
🔍 Root Causes
1
No Process Safety Management System for N2O
The fundamental organizational failure was the absence of any PSM framework for N2O operations — no PHA, no MOC, no MI.
2
Failure to Evaluate Safer Loading Technology
Airgas did not evaluate pumpless N2O loading methods that would eliminate the pump as a decomposition initiation risk. Inherently safer design options were not considered.
3
MOC Program Deficiency
Installing a pump in a N2O system without a MOC review allowed a new process hazard to be introduced without evaluation or compensating safeguards.
4
Regulatory Threshold Gap
The OSHA PSM threshold quantity for N2O exempts most production facilities from regulatory process safety requirements, despite N2O posing significant decomposition and explosion hazards.
☑ CSB Recommendations
→ Airgas
Implement a comprehensive process safety management system for all N2O production, storage, and loading operations, including formal PHA, MOC, and mechanical integrity programs.
→ Airgas
Evaluate and implement pumpless N2O loading systems that eliminate pump-induced overheating as an N2O decomposition initiation mechanism.
→ OSHA
Review the PSM threshold quantity for nitrous oxide and evaluate whether current thresholds adequately capture the process hazards at N2O production and loading facilities.
→ DOT
Develop specific safety standards for N2O trailer loading operations addressing pump overheating risk, decomposition prevention, and emergency shutdown requirements.
→ CGA / N2O Industry
Issue updated safety guidance for N2O production facilities specifically addressing decomposition hazard management, pump selection, and loading system design requirements.
💡 Lessons Learned
⚠ Nitrous oxide is a powerful oxidizer that can undergo catastrophic exothermic decomposition when overheated under confinement. It is not "safe" because of its medical or food applications — the chemistry is the same.
⚠ Process safety management is not only for OSHA PSM-listed chemicals. Any chemical that can decompose exothermically or react violently deserves a formal PHA and MOC program.
⚠ Management of change is required when new equipment is introduced to a process. Installing a pump in an N2O system is a process change that introduces new hazards.
⚠ Inherently safer design — evaluating whether a hazardous process step can be eliminated entirely — is among the most effective process safety investments. A pumpless loading method eliminates the pump decomposition risk at the source.
⚠ Regulatory thresholds define minimum mandatory requirements, not acceptable risk levels. Facilities near but below PSM thresholds must self-assess whether their processes pose hazards that require PSM-level controls.
PSM Elements: PHA · MOC · MI · PSI · SOP
🔨 Safety Meeting Toolbox Talk
Topic: N2O and Oxidizer Decomposition Hazards & PSM Application
💬Does our facility handle nitrous oxide, hydrogen peroxide, or other powerful oxidizers that can decompose exothermically under heating or confinement?
💬Have we applied PSM-quality process hazard analysis to all oxidizer handling and loading operations, regardless of whether we fall above or below OSHA PSM threshold quantities?
💬When new equipment was introduced into our oxidizer handling systems, was a formal MOC review conducted to evaluate new hazards introduced?
💬Have we evaluated whether inherently safer alternatives exist for high-hazard steps in our oxidizer handling operations — such as pumpless loading or pressure-differential transfer?
💬Do our mechanical integrity and operations procedures include specific temperature and pressure limits for all oxidizer handling equipment based on decomposition hazard characterization?
✎ Team Action Items
✓Identify all oxidizers in your facility — including N2O, H2O2, chlorine compounds, and peroxides — and confirm a formal PHA or hazard review exists for all handling and loading operations
✓Review the MOC records for all equipment installed in oxidizer handling systems in the past five years — verify each received a formal hazard review before installation
✓Ask your process engineer to confirm that temperature and pressure operating limits for oxidizer handling equipment are based on documented decomposition hazard characterization
✓Evaluate whether any high-hazard steps in your oxidizer handling process could be eliminated or replaced with an inherently safer alternative
🔗 PSM Failures Behind This Incident

This incident traced to breakdowns across 5 PSM elements (PHA · MOC · MI · PSI · SOP). Each represents a documented gap that process safety documentation and consulting can close before a similar event occurs at your facility.

Process Hazard Analysis (PHA)
A structured PHA or HAZOP study exists to identify exactly these scenarios before they occur. When PHA is absent, superficial, or overdue for revalidation, hazards operate unseen until they kill someone.
Supporting documents in our library →
Management of Change (MOC)
Changes to equipment, chemistry, operating limits, or procedures that bypass formal review create new hazard pathways your PHA never evaluated. MOC failures open the door to incidents like this one.
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Mechanical Integrity (MI)
Equipment must be designed, inspected, and maintained to operate safely in its intended service. Mechanical integrity failures — degraded equipment, missed inspections, deferred repairs — contributed to loss of containment here.
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Process Safety Information (PSI)
Accurate, complete Process Safety Information is the foundation every other PSM element depends on. When PSI is missing or wrong — chemistry data, equipment specs, P&IDs — the entire hazard analysis is built on a flawed base.
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Operating Procedures (SOPs)
Operators cannot reliably hold safe operating limits without clear, current, enforced procedures. Deviation from acceptable operating conditions — a root cause here — is a direct consequence of SOP failure.
Supporting documents in our library →
Process Safety Management Consulting & Document Library
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