What Does a Cooling Tower Explosion Mean for Chemical Manufacturers?

In their latest publication for the journal Process Safety Progress, Exponent's Trey Morrison, Brenton Cox, and Isaac Mastalski examine a fatal chemical cooling tower dosing system explosion at an industrial facility. The event offers valuable lessons for chemical plant operators, especially those responsible for utilities and "non‑process" systems. Although cooling water treatment is often seen as low risk, this case demonstrates that serious process safety hazards can still exist when chemicals are mishandled.

The explosion occurred when an operator attempted to dispose of an outdated liquid biocide by pumping it into an existing cooling tower treatment system. The system included a fiberglass‑reinforced plastic vessel containing solid oxidizing bromine tablets. The liquid biocide  —  later determined to be chemically incompatible with the oxidizer  —  was injected upstream of the feeder without sufficient dilution. When the two chemicals came into contact, a violent reaction rapidly generated heat and gas, overwhelming pressure relief protections and causing the vessel to explode. The operator was fatally injured by flying debris.

For operators, one of the most important takeaway is that chemical compatibility matters even in auxiliary systems. Utilities such as cooling water treatment, which often fall outside formal process safety management programs, can still present high consequence hazards when oxidizers, reducers, or other reactive chemistries are involved. The team's investigation showed that Safety Data Sheets alone were insufficient to clearly communicate the reactivity hazard, particularly to personnel without specialized chemical training.

The incident also underscores the operator's role in broader process safety systems. No formal management of change (MOC) review was conducted before introducing the aged biocide, no hazard analysis was performed, and no written procedures defined safe injection locations or rates. As a result, critical safeguards (such as bypassing the solid chemical feeder) were not used. Once pumping began, the operator had no practical way to intervene.

For chemical plant operators, this case reinforces several key practices: never assume two treatment chemicals are compatible; treat any change in chemical, injection point, or operating method as a potential MOC issue; rely on written procedures rather than informal guidance; and escalate uncertainty rather than improvising. Ultimately, Exponent's team confirmed that strong operational discipline and clear process safety controls are essential — not just in core process units but in utility systems as well.

From the publication: "The issues that led to the incident are not unique in the industry, and their consideration underscores the tenets of Risk Based Process Safety."