Breaking Down the CSB’s Findings on the Cuisine Solutions Ammonia Release | Blog No. 94

The Chemical Safety Board (CSB) recently released its final report on the hazardous ammonia release at Cuisine Solutions, a food processing facility in Virginia. At Macha PSM, we know these reports can be lengthy and dense, even the executive summaries. That’s why we’ve read through the full document for you. In this blog, we’ll break down what happened, highlight the CSB’s key findings, and share our perspective on the recommendations that could shape how the refrigeration industry approaches safety moving forward.

What Happened:

On September 25, 2025, the United States Chemical Safety and Hazard Investigation Board (CSB) released the final report on the hazardous ammonia release at Cuisine Solutions, a food processing plant located in Virginia. The incident occurred on July 31, 2024, when an overpressurization of a heat exchanger surge drum caused an emergency relief valve to open, releasing an estimated 275 pounds of anhydrous ammonia.

Instead of dispersing harmlessly into the atmosphere, some of the vapor contained liquid droplets in a phenomenon known as liquid entrapment. This two-phase discharge created a dense cloud that spread towards the employee parking lot. More than forty (40) workers required medical attention, four (4) were taken to the hospital, and one (1) spent time in intensive care.

What the CSB Found: 

The CSB found that there is no guidance in ANSI/IIAR 2 to prevent/mitigate 2-phase atmospheric discharges in pressure vessels that contain a saturated liquid with little vapor space. The findings also showed that the facility did not have Emergency Evacuation plans that addressed both indoor and outdoor releases with appropriate event-dependent notifications. Though the CSB concluded, after testing, that the pressure relief valves (PRVs) did properly lift and re-seat, we feel that it is important to note that the pressure relief valves were two years past the manufacturer's recommended replacement date. Due to the facility's lack of historical data on major equipment, the CSB could not determine the absolute cause of the ammonia release; however, the CSB believes that the event was started by a closed or restricted valve in combination with an upset to the process. Since the release was a 2-phase release, the suspended liquid in the ammonia cloud caused it to rapidly settle in on a main point of emergency egress and likely contained IDLH concentrations of ammonia.

What the CSB Recommended:

The CSB has two sets of Recommendations from the findings of the Cuisine Solutions Ammonia Release.

Recommendations to IIAR:

• “Update ANSI/IIAR 2a to include guidance for preventing or mitigating liquid or two-phase atmospheric discharges from emergency pressure relief systems, such as the guidance in API Standard 521, Pressure-relieving and Depressuring Systems.”

• “Update ANSI/IIAR 2 to include a requirement to assess whether emergency pressure relief devices discharge to a safe location, such as with a dispersion analysis.”

Recommendations to Cuisine Solutions:

• “Reduce the likelihood or mitigate the consequences of liquid or two-phase atmospheric discharges from the ammonia refrigeration emergency pressure relief system at the Sterling plant."

• "Implement an electronic process data historian and management system to ensure that critical process parameters are collected, tracked, and stored. The system should be available to refrigeration technicians so that they can monitor the refrigeration system and respond to and investigate process upsets."

• “Update the Cuisine Solutions Sterling site’s Emergency Action Plan using guidance such as the IIAR’s Critical Task Guidance for Ammonia Refrigeration System Emergency Planning.”

• “Add an alarm or alarms specific to ammonia releases, so that workers can properly respond to a release. The alarm response should be documented in the updated Emergency Action Plan, and may include multiple distinct alarms and responses, such as one for shelter-in-place and one for evacuation.”

This week’s blog focused on the facts presented in the CSB’s findings. Be sure to check back next week when we’ll share Macha PSM’s interpretation of these findings and how we’re adapting our product to enhance safety and help ensure our customers remain the safest in the industry.

Previous Blog: Early Lessons from My First Weeks in the Field | Blog No. 93

Works Cited: U.S. Chemical Safety Board Releases Final Report on July 2024 Hazardous Ammonia Release at Cuisine Solutions Facility in Sterling, Virginia

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