Combustibility Determination for Walnut Hulling and Shelling Facility Dusts

Area of Science:

• Agricultural Processing Safety
• Industrial Dust Hazards
• Material Flammability Testing

Background:

• Agricultural facilities face risks from fires and explosions.
• Walnut dust is classified as combustible by the U.S. Occupational Safety and Health Administration (OSHA).
• This classification can impose costly safety requirements on walnut hulling and shelling operations.

Purpose of the Study:

• To determine the actual combustibility of walnut huller and sheller dust.
• To assess whether walnut dust meets the criteria for flammable solids.
• To inform regulatory and insurance requirements for agricultural processors.

Main Methods:

• Dust samples were collected from California-based walnut hulling and shelling facilities.
• Combustibility tests were performed following the United Nations Manual of Tests and Criteria, Part III, Subsection 33.2.1, Test N.1.
• The tests specifically evaluated the dust's properties as flammable solids.

Main Results:

• Walnut huller and sheller dusts were found not to be flammable solids.
• The dust samples did not meet the criteria for classification as combustible dust.
• Standardized testing provides evidence against the current OSHA classification.

Conclusions:

• Walnut dust should not be classified as a combustible solid based on recognized testing standards.
• The designation of walnut dust as combustible may lead to unnecessary and expensive safety installations.
• Re-evaluation of walnut dust's combustibility classification is recommended for agricultural processors.