Material
Expanded Polystyrene Beads
Answer in brief
EPS beads weigh almost nothing and bring a flammable gas with them.
Pre-expanded beads release residual pentane during ageing, so the silo atmosphere is the controlling design question rather than the flow behavior.
- Ventilate storage continuously and monitor for flammable atmosphere.
- Ground everything, because beads charge strongly in air conveying.
- Convey gently, since the bead structure is what gives the product its value.
Reviewed October 21, 2026 · Updated October 21, 2026
Handling challenges
EPS handling systems move huge volumes of almost no mass, and the hazard travels with the material rather than being created by it.
Pentane release
Pre-expanded beads continue to release blowing agent during ageing, and pentane is heavier than air and flammable.
- Continuous ventilation of ageing silos, with the extract routed safely.
- Gas detection at low level, where pentane accumulates.
- Electrical equipment selected for the classified zone.
Static
Air conveying charges beads strongly, and the charge both makes them cling and creates an ignition source in a flammable atmosphere.
Conductive, grounded ducting and controlled velocity are basic requirements rather than refinements.
Low density conveying
The beads convey easily on low pressure air, but velocity breaks and deforms them.
Large duct diameters at modest velocity move the product gently and keep pressure drop reasonable.
Storage
Fabric ageing silos are normal because they ventilate and are light.
Flow is generally good, but very low density means bridging is possible over small outlets.
What to establish before buying equipment
- Residual pentane content and the ageing time required.
- Ventilation rate and gas detection strategy.
- Bead size and the acceptable deformation across the line.
- Area classification for electrical equipment.
Material behavior
- Flowability
- Free flowing, extremely low bulk density
- Abrasiveness
- Very low
- Cohesiveness
- Low, but static causes strong clinging
- Moisture behavior
- Surface moisture affects moulding, not flow
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