On December 26, 1989, Employee #1 was attempting to replace a leaking oil valve on a minus 30-degree freezer when a tank inside the freezer exploded. The company uses anhydrous ammonia to manufacture ice cream. The liquid ice cream mixture (at 50 degrees) is added to the tank. When the liquid ammonia changes to a gas, the liquid ice cream mixture becomes solid. As the ammonia gas pressure builds up inside the tank, it is sucked out in a suction line and directed through the system. This freezer was down for seven days and the oil inside the tank had congealed.