Expanded Polystyrene Beads

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.

Expanded beads are almost all air, and that changes every assumption.

A silo that looks large holds very little mass, static charge makes beads cling to everything, and pre-expanded beads continue to change while they rest, which is why ageing is a deliberate process step rather than storage.

• Treat ageing silos as process equipment with controlled time and ventilation.
• Earth and bond everything; static is both a handling nuisance and an ignition source.
• Ventilate: pre-expanded beads release residual pentane as they rest.

Low density and static set the design.

Material is moved with large volumes of air at low pressure, so the equipment is sized by volume rather than by mass, and every component in contact needs to be conductive and earthed.

• Large-diameter low-pressure conveying lines.
• Conductive, earthed hoses and components throughout.
• Filters sized for a very light dust that does not settle readily.

Residual pentane is the hazard that governs the plant.

Pentane is a flammable gas, it is heavier than air, and it collects in pits, ducts and at floor level where nobody is looking for it.

• Gas detection at low level, not at head height.
• Ventilation designed for a gas that sinks.
• Ignition source control: earthing, bonding and rated electrical equipment.