- Stored material
- Flour or a flour-based blend
- Key risks to assess
- Dust, engulfment and product contamination
- Identify
- Exact flour or blend and next product
- Release criteria
- Set by the food-business hygiene plan
Flour type and product history
A silo may contain wheat flour, another flour or a formulated blend. The exact product, relevant allergens and previous contents affect the cleaning standard, particularly where the silo is being prepared for a product changeover.
Deposits on walls, around outlets or on internal features can differ from the free-flowing product. Retained material can fall when disturbed, so its position, thickness and condition matter.
Flour dust and cleaning controls
HSE identifies flour as a material whose dust can create a fire or explosion hazard in the right conditions. Cleaning therefore needs to control ignition risks and avoid unnecessary dispersal of fine dust.
Compressed air or uncontrolled disturbance can move flour from one surface to another and increase airborne dust. The cleaning method should collect residue rather than spread it into neighbouring production areas.
Dry and wet cleaning considerations
Wet cleaning is not automatically suitable for a dry flour silo. Water can alter dry residues, and any use of moisture has consequences for drainage, drying and the condition required before the silo is refilled.
Where a suitable non-entry method can achieve the required result, internal access should be avoided. An apparently empty silo may still contain retained material and can present confined-space or engulfment hazards, so any entry requires a separate competent assessment.
Hygiene and return to use
The required finish depends on the food business’s hygiene controls, the next product and any allergen requirements. Before refill, it should be clear which surfaces were included, what remains inaccessible and what inspection or verification is required. Pest treatment and mechanical repairs are separate from removal of flour residues.