- Type
- Flat-bottom / flat-floor silo
- Identify
- Reclaim equipment and floor construction
- Separate checks
- Material removal, machinery condition and readiness for refill
Flat floors and discharge arrangements
Flat-bottom silos store bulk materials such as grain. The floor, discharge points and unloading equipment form part of the cleaning area alongside the walls, and the floor construction can change access to retained deposits.
Material can remain around the perimeter, outlets, aeration channels or other recesses after normal unloading. An apparently empty discharge point does not establish that these areas are clear.
Reclaim equipment and retained material
Sweep augers and other powered reclaim systems bring moving machinery and connected drives into the cleaning area. Their arrangement, together with the floor components around them, affects access and the limits of the work.
Bridging and ratholing can also leave material behind even when some product continues to discharge. These are bulk-flow behaviours and may indicate a problem that deposit removal alone will not correct.
Stored product and cleaning method
The product, deposit condition and next stored material influence the method. Food dusts can create fire and explosion hazards, while moisture may make wet cleaning unsuitable for a dry-product installation or alter the residue itself.
Where a suitable non-entry method can achieve the required result, unnecessary internal access should be avoided. Any proposed entry needs a competent confined-space assessment and appropriate isolation of reclaim and conveying equipment.
Condition before refill
Before refill, it should be clear which surfaces and connected equipment were cleaned, what remained inaccessible and what checks are required. Product changeovers may also need hygiene or contamination criteria beyond visible removal of loose material.
The cleaning method and return-to-use standard need to reflect the floor construction, discharge arrangement, reclaim equipment and stored material.
Sources and further reading
- Symaga: flat-bottom silos — Manufacturer geometry and components; specifications are product-specific.
- Jenike & Johanson: poor bulk-solids flow — Arching, ratholing and mass/funnel flow; no universal clean or design setting.
- HSE: dust explosions in the food industry — Food-dust hazard assessment and control principles.
- HSE: introduction to confined spaces — Great Britain confined-space assessment and avoiding entry where possible.