Areas of expertise include mechanical engineering, forensics, and subrogation

 

Scenario

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One of two ammonia refrigeration systems at a cold storage facility leaked causing over $180 million in damage to frozen food products.

 

ProNet Group was retained by a leading subrogation law firm on behalf of a frozen seafood company to evaluate and determine the cause of the ammonia refrigerant system leak and the ammonia refrigeration system outage that affected their clients frozen seafood products.

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Additional Information

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ProNet’s senior mechanical engineer, who is a member of ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) and IIAR (International Institute of Ammonia Refrigeration), participated in multiple joint scene inspections of the refrigerated facility, refrigeration system mechanical rooms, and related components at the refrigerated warehouse, along with experts and attorneys of other interested parties.

 

The refrigerated warehouse experienced an electrical power outage, which occurred concurrently with an ammonia refrigerant release in the mechanical room.  The ammonia gas from the subcooled liquid ammonia leak was reportedly detected throughout the facility, which was deemed unsafe for human occupancy from the onset of the leak until one week later. 

 

The reported cause of the refrigeration system leak was the physical separation of a bullseye level liquid indicator on the ammonia refrigeration vessel level column.  The failed bullseye components, including the housing, pressure gasket, lens, fiber gasket, retainer and frost lens were examined.

 

Outcome

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After multiple visual examinations of the facility’s ammonia refrigeration system, the failed bullseye liquid level indicator and other components, research of pertinent component manufacturers as well as risk factors for ammonia refrigeration hazards and controls, and review of ASHRAE Safety Standards for Mechanical Refrigeration, the following was concluded:

 

• The facility ammonia detection system, with ammonia sensors in the mechanical room, could not operate as intended because of the power failure and the absence of back-up power generation equipment.

• The mechanical ventilation fans in the mechanical room could not operate as intended because the power failure and the absence of back-up power generation equipment, thus not activating the ammonia detection system.

• The ammonia refrigerant that was released from the failed bullseye liquid level indicator could not be exhausted from the mechanical room because the power outage prevented automatic ventilation fan operation from the ammonia detection system, causing the elevated ammonia gas levels measured throughout the facility and the resulting frozen food losses.

 

It was further concluded that construction of the mechanical room as a building detached from the refrigerated warehouse would have eliminated the direct path of ammonia refrigerant into the refrigerated loading dock and storage rooms, and thus prevented any product damage due to ammonia contamination.