STATIC SPARK IGNITION — NONCONDUCTIVE SOLVENT — 6,000 EVACUATED
Barton Solvents Static Spark Tank Farm Explosions
Barton Solvents, Inc.
📍 Valley Center, KS (near Wichita)
Incident: July 17, 2007  •  CSB Report: June 2008
0
Fatalities
VM&P Naphtha (Nonconductive Flammable Liquid — Static Spark Ignition During Tank Filling)
Chemical Involved
7
CSB Recommendations
📋 Incident Summary

On July 17, 2007, explosions and fire erupted in the outdoor tank storage area at Barton Solvents in Valley Center, Kansas. Approximately 6,000 residents were evacuated. There were no fatalities or serious injuries, but the facility sustained extensive damage. Barton Solvents packages, stores, and distributes solvents and chemical products.

A tanker truck was offloading VM&P naphtha (a nonconductive flammable liquid) into a 15,000-gallon storage tank when the incident occurred. The CSB determined that a static spark ignited the air-vapor mixture inside the tank. The spark most likely originated from a metal float used to measure liquid level — as the tank was filled, the float oscillated and generated a static discharge sufficient to ignite the vapor-air mixture.

The CSB investigation highlighted a broadly misunderstood hazard: nonconductive flammable liquids can accumulate static charge during transfer and are more prone to static-ignition events than conductive liquids. MSDSs at the time did not adequately address this hazard, and industry awareness was insufficient.

🔎 Key Findings
Finding 01
Static Spark Ignited Vapor Inside Tank During Transfer
The most likely ignition source was a static electric discharge generated by a metal float device inside the storage tank as naphtha was being transferred in. The static spark ignited the air-vapor mixture at the tank vent.
Finding 02
Nonconductive Flammable Liquids Accumulate Static Charge
VM&P naphtha is a nonconductive flammable liquid. Unlike conductive liquids that dissipate static charge rapidly, nonconductive liquids accumulate static charge during pumping and transfer, creating ignition risk even with bonding and grounding in place.
Finding 03
Inadequate Hazard Information for Nonconductive Solvents
MSDSs for VM&P naphtha and similar nonconductive flammable liquids did not adequately warn users of the static accumulation hazard — leaving many operators unaware of the distinct risk.
Finding 04
Metal Float Device Created Static Generation Point
The metal float used for level measurement was a static generation point during tank filling. Metal floats in nonconductive liquid service can generate static discharges sufficient to ignite vapor-air mixtures.
Finding 05
6,000 Residents Evacuated — Community Impact
The scale of evacuation illustrates the community impact of industrial tank farm fires even when no workers or members of the public are killed.
🔍 Root Causes
1
Static Charge Accumulated in Nonconductive Naphtha During Transfer
Naphtha accumulated static charge as it was pumped into the storage tank. Standard bonding and grounding practices reduce but do not eliminate static ignition risk for nonconductive liquids.
2
Metal Float Generated Static Discharge Sufficient to Ignite Vapor
The metal float in the tank oscillated during filling, generating a static spark that ignited the air-vapor mixture — a scenario specific to nonconductive liquid service with metal internal components.
3
Workers and Management Not Aware of Specific Static Hazard
The static accumulation hazard of nonconductive flammable liquids was not communicated in available hazard information, and the facility had not taken specific measures to address this hazard beyond standard bonding and grounding.
☑ CSB Recommendations
→ OSHA / Chemical Manufacturers
Update hazard communication requirements to specifically address the static accumulation hazard of nonconductive flammable liquids; distinguish static hazard of nonconductive versus conductive liquids.
→ Barton Solvents / Flammable Liquid Storage Facilities
Replace metal float level devices in nonconductive flammable liquid service with non-sparking alternatives; review all storage tank internal components for static generation potential.
→ API / NFPA / Industry Standards
Update guidance on transfer and storage of nonconductive flammable liquids to address specific static hazard mitigation beyond standard bonding and grounding.
→ Chemical Distributors
Conduct hazard reviews for all nonconductive flammable liquid transfer and storage operations; implement specific static mitigation measures (slow fill rates, anti-static additives, non-sparking hardware) as appropriate.
💡 Lessons Learned
Bonding and grounding alone are not sufficient to prevent static ignition when transferring nonconductive flammable liquids. Nonconductive liquids accumulate static charge during pumping and do not dissipate it rapidly to ground as conductive liquids do. This is a fundamental physical property difference that must be recognized and addressed with additional static mitigation measures beyond standard bonding.
Metal components inside tanks storing nonconductive flammable liquids — floats, internal pipes, gauging devices — can generate static sparks when they move in contact with the charged liquid or charged vapor. These internal sources of static ignition are not addressed by external bonding and grounding, and require specific attention in equipment specification and PHA.
Material Safety Data Sheets are often the primary source of hazard information for chemical storage and transfer operations. When SDSs do not accurately communicate the specific static hazard of nonconductive flammable liquids, facilities operating these materials cannot implement appropriate safeguards. Accurate, specific hazard communication is a prerequisite for effective hazard control.
The evacuation of 6,000 residents from a tank farm fire illustrates that flammable liquid storage facilities have community impact well beyond the facility fence. Emergency planning must include off-site notification protocols, community evacuation planning, and coordination with local emergency response.
PSI: Process Safety InformationSOP: Operating ProceduresEAP: Emergency PlanningMI: Mechanical Integrity
🔨 Safety Meeting Toolbox Talk
►Does your facility store or transfer nonconductive flammable liquids? If so, do your procedures and PSI specifically address the static accumulation hazard beyond standard bonding and grounding?
►Do any storage tanks with nonconductive flammable liquids have metal internal components (floats, internal pipes, dip tubes) that could generate static sparks?
►Does your SDS for nonconductive flammable liquids accurately communicate the static accumulation hazard, distinguishing it from conductive liquid behavior?
►Does your emergency planning include off-site community notification and evacuation protocols for a large flammable liquid tank fire?
Immediate Action Items
✓Identify all nonconductive flammable liquids stored or transferred at your facility; review transfer procedures for specific static mitigation measures beyond bonding and grounding.
✓Inspect internal components of all storage tanks with nonconductive flammable liquids for potential static generation points; replace with non-sparking alternatives as needed.
✓Verify that SDSs for nonconductive flammable liquids accurately communicate the static accumulation hazard; update any SDSs that treat static hazard generically.
✓Review emergency response plans for tank farm fires; confirm off-site community notification protocols are current and coordinated with local fire and emergency management authorities.
🔗 PSM Failures Behind This Incident

This incident traced to breakdowns across 4 PSM elements (PSI · SOP · EAP · 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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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.
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Emergency Planning & Response
When process safety barriers fail, emergency response capability determines whether the outcome is controlled or catastrophic. Gaps in emergency preparedness amplified the consequences here.
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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.
Supporting documents in our library →
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