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Parent Category: Safety Info Posts

Category: Chemical Process Safety (PSM/RMP)

Published: 14 August 2017

UPDATED 8/15/2017 with OSHA Case info:  This has now been classified as a "Hot Gas Defrost Valving Error".

On September 11, 2012, Employee #1, a temporary employee was working as a racker-blender at the [wine company], was exposed to anhydrous ammonia, and died of asphyxia. Employee #1 was found in the west hallway 54 ft from the men's restroom. Upon further investigation, a cellar supervisor was to clear iced juice in Chiller 13 by performing a "hot gas" procedure.  The evaporator's temperature is raised by opening a bypass valve that equalizes the refrigerant pressure. The cellar supervisor was distracted in conversation with a graveyard shift supervisor and inadvertently opened the dump valve. The dump valve purges excessive oil from the refrigerant system into a barrel of water.  The opening of the dump valve instead of the bypass valve caused oil to discharge and liquid ammonia to release forming a gas cloud. The cellar supervisor evacuated the area but left the dump valve open. The gas cloud engulfed the area and was pushed against the building containing two hallways, a men and women's bathroom, and a break room. The gas cloud formation was captured on a surveillance video, but dissipated within seconds. Approximately one minute before the release, Employee #1 entered the west hallway. It was calculated the refrigerant charge at the facility was 23,640 pounds of anhydrous ammonia.

NOTE: this was a CAL-OSHA case and why they did not issue any PSM citations is unknown- it could be the facility was fully compliant with 5189 - Process Safety Management of Acutely Hazardous Materials.  The citations totaled $2,250.  Here is what CAL-OSHA cited:

SAFTENG MEMBERS can see CAL-OSHA's presentation on this fatality case HERE

Here is what CAL-OSHA cited:

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