Explosion And Fire
US Ink Solvent Fire and Explosion
US Ink (A Division of Sun Chemical)
📍 East Rutherford, NJ
Incident: April 12, 2012 • CSB Report: 2014
2
Fatalities
6
Injuries / Affected
Flammable Ink Solvents — Heptane and Petroleum Distillates (Flash Fire and Explo
Chemical Involved
3
CSB Recommendations
📋 Incident Summary

On April 12, 2012, two workers were killed and six others were injured in a fire and explosion at the US Ink Corporation manufacturing facility in East Rutherford, New Jersey. US Ink produced printing inks, and the manufacturing process used large quantities of flammable solvents — including heptane and petroleum distillates — as ink vehicle components.

The fire and explosion occurred when flammable solvent vapors accumulated in an area of the facility and found an ignition source. The released vapors ignited and produced a flash fire and explosion that killed two workers in the immediate area and injured six others. The incident caused significant damage to the production facility.

The CSB investigation found deficiencies in the process safety management of flammable solvent handling at US Ink. The investigation identified inadequate ventilation design for the solvent handling area, missing explosion-proof electrical equipment, and deficiencies in the operating procedures and training for flammable solvent operations.

🔎 Key Findings
Finding 01
Flammable Solvent Vapors Accumulated — Flash Fire and Explosion
Flammable ink solvent vapors accumulated in the production area and found an ignition source, producing the flash fire and explosion that killed two workers.
Finding 02
Ventilation System Inadequate to Prevent Flammable Vapor Accumulation
The ventilation system in the flammable solvent handling area was not adequate to prevent the accumulation of flammable vapors to above the Lower Explosive Limit (LEL). Inadequate ventilation allowed vapors to build to explosive concentrations.
Finding 03
Non-Explosion-Proof Electrical Equipment Present in Flammable Vapor Zone
Electrical equipment in the area where flammable vapors were handled was not explosion-proof or adequately classified for the flammable vapor zone. Non-classified electrical equipment provided an ignition source for the accumulated flammable vapors.
Finding 04
Two Workers Killed — Six Injured
Two workers in close proximity to the flash fire initiation point were killed. Six others were injured. The flash fire spread rapidly through the area of flammable vapor accumulation.
Finding 05
Operating Procedures Did Not Adequately Address Flammable Solvent Handling Hazards
Operating procedures for flammable solvent handling at US Ink did not adequately address the ventilation requirements, ignition source control, and flammable vapor monitoring required to safely manage large quantities of flammable solvents in the production area.
🔍 Root Causes
1
Inadequate Ventilation Allowed Flammable Vapor Accumulation to Explosive Concentration
The flammable solvent handling area did not have adequate ventilation to maintain vapor concentrations below the LEL. Vapors accumulated to explosive concentrations and found an ignition source.
2
Non-Explosion-Proof Electrical Equipment Provided Ignition Source
Electrical equipment in the flammable vapor zone was not explosion-proof, providing a potential ignition source for the accumulated flammable vapors. Electrical classification requirements had not been correctly applied to the solvent handling area.
3
Flammable Solvent Hazard Controls — Ventilation, Electrical Classification, Monitoring — Were Inadequate
The combination of inadequate ventilation, non-classified electrical equipment, and the absence of continuous flammable vapor monitoring created conditions in which a flash fire and explosion was a foreseeable outcome of solvent handling operations.
☑ CSB Recommendations
→ US Ink / Sun Chemical / Ink Manufacturers
Conduct electrical area classification for all flammable solvent handling areas consistent with NEC and NFPA 70; replace non-classified electrical equipment in classified areas; implement continuous flammable vapor monitoring in solvent handling areas; verify ventilation design is adequate to maintain vapor concentrations below 25% LEL.
→ Printing Ink Industry / NAPIM
Develop industry guidance on flammable solvent safety in ink manufacturing facilities; address ventilation design, electrical classification, and vapor monitoring requirements for large-volume flammable solvent operations.
→ OSHA
Conduct targeted PSM inspections at ink manufacturing and other facilities using large quantities of flammable solvents; evaluate electrical classification and ventilation adequacy in flammable solvent handling areas.
💡 Lessons Learned
Electrical area classification is one of the most fundamental process safety requirements for facilities handling large quantities of flammable liquids and vapors. The National Electrical Code and NFPA standards provide specific classification requirements for areas where flammable vapors can be expected to exist under normal, abnormal, or maintenance conditions. Facilities that handle large-volume flammable solvents must conduct formal area classification studies and must install explosion-proof electrical equipment in all classified areas. Non-classified equipment in a flammable vapor zone is an ignition source waiting for a flammable accumulation.
Ventilation for flammable solvent handling areas must be designed to maintain vapor concentrations below 25% of the Lower Explosive Limit — not just to provide general air circulation. General ventilation requirements for OSHA compliance and flammable vapor control ventilation requirements are not the same thing. The ventilation design for a large-volume flammable solvent area must be based on the maximum expected vapor generation rate and the required dilution airflow to maintain concentrations below the LEL safety threshold.
Continuous flammable vapor monitoring in large-volume solvent handling areas provides the critical early warning that allows workers to evacuate and operations to be shut down before vapor concentrations reach explosive levels. LEL monitors should be installed at breathing height and at locations where vapors are expected to accumulate. Alarm setpoints should be set at 10% LEL for evacuation warning and 25% LEL for automatic system shutdown. Without monitoring, workers have no warning that the environment has become hazardous before ignition occurs.
PSI: Process Safety InformationPHA: Process Hazard AnalysisSOP: Operating ProceduresMI: Mechanical Integrity
🔨 Safety Meeting Toolbox Talk
►Has a formal electrical area classification study been conducted for all flammable solvent handling areas at your facility? Has explosion-proof electrical equipment been installed in all classified areas, and has non-classified equipment been removed?
►Has the ventilation design for flammable solvent handling areas been verified to maintain vapor concentrations below 25% LEL under all normal and foreseeable upset conditions? When was the ventilation system last tested for design flow rate?
►Are continuous LEL monitors installed in all large-volume flammable solvent handling areas? Are alarm setpoints set at 10% LEL for evacuation warning? Are monitors calibrated and maintained on schedule?
Immediate Action Items
✓Conduct a formal electrical area classification study for all flammable solvent handling and storage areas; identify any non-classified electrical equipment in classified zones and schedule replacement with explosion-proof alternatives.
✓Verify ventilation design basis for all flammable solvent handling areas; test current ventilation airflow against the design requirement to maintain vapor concentrations below 25% LEL.
✓Audit flammable vapor monitoring in solvent handling areas; verify LEL monitors are installed in appropriate locations, calibrated, and set to alarm at 10% LEL.
✓Review operating procedures for flammable solvent handling; add requirements for verifying ventilation operation, confirming ignition source control, and confirming LEL monitor status before beginning solvent handling operations.
🔗 PSM Failures Behind This Incident

This incident traced to breakdowns across 4 PSM elements (PSI · PHA · SOP · MI). Each represents a documented gap that process safety documentation and consulting can close before a similar event occurs at your facility.

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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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.
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Operating Procedures (SOPs)
Operators cannot reliably hold safe operating limits without clear, current, enforced procedures. Deviation from acceptable operating conditions is a direct consequence of SOP failure.
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Mechanical Integrity (MI)
Equipment must be designed, inspected, and maintained to operate safely in its intended service. Mechanical integrity failures contributed to loss of containment here.
Supporting documents in our library →
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