Industries
Explosion protection in the plastics industry
Plastics manufacturing produces combustible dust: granulates, powders and ground material form an explosive atmosphere during grinding, milling, sieving and pneumatic conveying. Fine plastic dust often ignites at low energy, and processing is in constant motion: a new raw material, a new colourant, a new machine. The documentation has to keep the dust zones, the equipment and the protective measures current.
Industry experience
Sound familiar?
A mill or dust collector is replaced, but the zone classification and the protective measures do not follow the change.
Dust charges up in the pneumatic conveying system, and it is not clear whether the earthing and static dissipation are sufficient.
Regranulate is processed, but nobody has assessed the explosion risk of the fine dust it produces.
A solvent-based coating or additive is used, but the vapour zone and the dust zone are not handled together.
Ahead of an audit you spend days gathering the zone drawings, the equipment list and the inspection certificates.
If any of this sounds familiar, what you need is not another document but software that changes along with the equipment and the protective measures.
Hazards
Typical explosion hazards in the plastics industry
The main hazard in this industry is plastic dust, but solvents and additives can accompany the processing:
| Hazard source | Where typical | Typical zone |
|---|---|---|
| Plastic dust (granulate, ground material, regranulate) | grinding, milling, sieving, mixing | dust zone (20/21/22) |
| Dust in pneumatic conveying | conveying lines, silos, dust collectors | dust zone (20/21) |
| Settled dust | hall surfaces, the tops of machines | dust zone (22), secondary explosion |
| Solvent vapour and additives | coating, solvent cleaning, dosing additives | gas zone (1/2) |
| Electrostatic charging | pneumatic conveying, plastic surfaces, filling | an ignition source in every zone |
How violent plastic dust is comes down to two characteristics of a dust explosion: the Kst value shows the rate of pressure rise, and the minimum ignition energy shows how easily it ignites. Fine dusts, particularly those from processing regranulate, can ignite at low energy. Plastic is also prone to electrostatic charging, which makes pneumatic conveying and filling a prominent ignition source. The highest-risk points are the mills, the grinders and their dust collectors.
When we help
Typical situations when it’s worth talking
Plastic dust and static charging
What distinguishes the plastics industry is that the dust and a material prone to charging are present in the same place. This has to be managed on four points:
Fine dust ignites at low energy. Grinding and milling produce fine dust; the finer the particle, the less energy it takes to ignite.
Plastic charges up. Pneumatic conveying, insulating surfaces and filling build static charge, in precisely the dust zones.
The equipment has to be isolated. Explosion isolation prevents an explosion from propagating along conveyors and ducts.
Settled dust has to be removed. The cleaning regime is part of explosion protection, because dust stirred up can cause a secondary explosion.
The solution
How EPDS helps in the plastics industry
EPDS brings explosion protection documentation into one system, from the dust data through to the protective measures:
Dust, zone and equipment register in one place.
EPDS holds the Kst and MIE data of the dusts, the zones and every Ex device in one searchable place.
Gas and dust in one system.
Where a solvent-based coating or additive is also present, EPDS handles the vapour zones and the dust zones together.
Management of change.
The software traces the effect of a new machine, raw material or process through the zones and the protective measures.
No more overdue inspections.
The system gives notice of inspections as they fall due, and records the ones completed.
An audit-ready report in one click.
EPDS assembles the report of zones, equipment and inspections, per site too.
Documentation that is always current.
You can look back at any time to see who changed what, and when.
Knowledge hub
Before you decide, get informed.
Our expert knowledge base explains the concepts of explosion protection clearly.
FAQ
Frequently asked questions
Is plastic dust really an explosion hazard?
Yes. Fine plastic dust is combustible, and dispersed in air it forms an explosive cloud. Finer particles ignite at lower energy, which makes the dust from grinding, milling and regranulation a particular risk.
Why does static charging matter in the plastics industry?
Plastic is a good insulator, so it charges up easily, particularly during pneumatic conveying and filling. A discharge can ignite the dust cloud, which makes earthing, equipotential bonding and static dissipation the basis of the protection.
Which equipment carries the greatest risk?
The mills, the grinders and the dust collectors, because the dust in them is often present at an explosive concentration. It is worth protecting these with isolation as well, so that an explosion cannot propagate further.
When does the zone classification have to be redone?
At every change that affects the explosion hazard: a new machine, a different raw material, introducing regranulation, or a modification to the conveying or the extraction. In EPDS this is part of management of change.
Does a plastics processing plant need explosion protection documentation?
Yes. Wherever a combustible dust or vapour can create an explosive atmosphere, the documentation is mandatory under decree 3/2003. (III. 11.), and it has to be kept current.
Let’s talk it through — free consultation
In a short, free conversation we show you the EPDS system mapped onto your processes, and review where your documentation stands today.