Storing EPS raw material: shelf life and pentane loss

EPS raw beads contain pentane, the blowing agent that makes them expand in the pre-expander. Pentane slowly escapes from the beads over time, and faster when it is warm. Beads that have lost too much pentane expand less, need more steam and give heavier or poorly fused parts. Good storage keeps your material working the way it did on the day it arrived.

Where to store it

• Store bags indoors, at normal room temperature, in a well-ventilated area.
• Keep them out of direct sunlight. Heat is the main cause of pentane loss, so also keep bags away from boilers, steam lines and hot roofs.
• Keep bags closed until you use them, and keep them off wet floors.

Open only what you can use

Once a bag is opened, pentane loss speeds up. This is why the choice between 25 kg paper bags and 750–850 kg jumbo bags matters. A jumbo bag should be used in one continuous run after it is opened. Plants that cannot do that, for example because their daily output is small, are usually better served by 25 kg bags. If you must stop part-way, close the bag tightly.

Shelf life: generally 6 months

EPS raw material generally has a shelf life of 6 months when stored as described above. Mark each delivery with its arrival date, use the oldest stock first, and plan your orders so that each delivery is used well within that time. Remember that sea freight takes part of it.

Pentane is flammable

Pentane released from beads can form flammable vapour, especially in closed spaces and around the pre-expander. Ventilate storage and silo areas, keep open flames and sparks away, earth your equipment and follow the safety data sheet (SDS) for the grade you use.