What FRAS Means
FRAS stands for Fire Resistant Anti-Static. It describes a conveyor belt specification required for underground mine applications β primarily underground coal mines β where a burning belt could cause a catastrophic fire or explosion, and where static electricity buildup could ignite methane gas.
A standard conveyor belt is not FRAS rated. Using a standard belt underground where FRAS is required is a safety violation and a serious risk.
Why Underground Mines Need FRAS Belts
Fire risk. In an underground coal mine, a belt fire is one of the most dangerous events possible. If a belt catches fire due to friction (from a seized idler, for example), the fire spreads along the belt, propagating into the mine. A standard SBR rubber belt burns readily. A FRAS belt resists ignition and self-extinguishes when the ignition source is removed β it does not sustain combustion.
Static electricity and methane. Conveyor belts moving at speed can generate static electricity through friction with idlers and material. In a methane-bearing underground environment, a static discharge could ignite the gas. FRAS belts have sufficiently low electrical surface resistance to bleed static charges safely to ground before they build up to dangerous levels.
The Two Properties: Fire Resistance and Anti-Static
Fire resistance is tested by exposing the belt to a flame for a specified time, then measuring how much the burning continues after the flame is removed. Standards specify the belt must self-extinguish within a set time (typically 1β3 seconds) and the burn length must not exceed a specified distance.
Key test standards: - SANS 971 (South Africa) - AS 4606 (Australia) - EN ISO 340 (Europe) - MSHA (USA) - Various national standards in India, China, Russia
Each standard has slightly different test conditions and acceptance criteria. A belt certified to Australian AS 4606 is not automatically certified to South African SANS 971 β these are separate certifications.
Anti-static (electrical resistance) is tested by measuring the electrical surface resistance of the belt cover. FRAS standards specify a maximum resistance β typically 3 Γ 10βΈ ohms or similar β to ensure static charges bleed away rather than accumulating.
Side-by-Side Comparison
| Property | Standard Belt | FRAS Belt |
|---|---|---|
| Fire resistance | Burns and sustains combustion | Self-extinguishes; tested per applicable standard |
| Electrical resistance (surface) | Not controlled β can accumulate static | Controlled β maximum resistance specified |
| Cover compound | Standard SBR, NR, or EPDM | Modified compound with flame retardant additives |
| Abrasion resistance | Full M24 or N17 grades | Slightly lower than standard due to FR additives |
| Cost | Standard | Higher β specialty compound |
| Available certifications | None required | Certification to applicable national standard |
| Suitable for underground coal | No (in most jurisdictions) | Yes β required |
| Suitable for surface applications | Yes | Yes β but unnecessary cost premium |
Which Certification Do You Need?
This depends entirely on your mine's location and regulatory authority:
- Australia: AS 4606 β required by Australian state mining safety regulators
- South Africa: SANS 971 β required by DMRE (Department of Mineral Resources and Energy)
- India: DGMS (Directorate General of Mines Safety) approval
- USA: MSHA (Mine Safety and Health Administration) approval
- Europe: EN ISO 340 and national mining authority requirements
- China: GB/T 10822 and State Administration of Work Safety requirements
Important: We supply FRAS belts with test documentation. Whether our certification documentation satisfies your specific regulatory authority is something buyers must confirm with their mine safety officer or the relevant regulatory body. We don't make compliance guarantees β we provide the test data and let the appropriate authority make the determination.
Common Misunderstandings
"FRAS means the belt won't burn." Not correct. FRAS belts resist sustained combustion β they self-extinguish when the flame source is removed. A FRAS belt will still char and damage if exposed to prolonged high heat. FRAS is about preventing fire propagation, not making the belt fireproof.
"Any underground belt needs to be FRAS." Requirements vary by jurisdiction, mine depth, gas classification, and specific regulations. Some underground hard rock mines (gold, copper) have different requirements than underground coal. Confirm your specific requirements with your mine safety officer.
"A FRAS belt lasts as long as a standard belt." In general practice, FRAS belts have slightly lower abrasion resistance than standard M24 grade because the flame-retardant additives affect the rubber's wear properties. The difference is typically not large enough to be a practical issue, but it's worth being aware of.
Frequently Asked Questions
Our mine has been using standard belts underground. Is this a problem? If your jurisdiction requires FRAS belts for underground use and you're running standard belts, that is a regulatory compliance issue. We'd recommend confirming requirements with your mine safety officer rather than relying on our answer.
Can FRAS belts be used on surface conveyors? Yes β FRAS belts work on surface conveyors. There's no technical reason not to use them on surface. However, they cost more than standard belts, so using FRAS on surface applications where it's not required adds unnecessary cost.
Do you supply FRAS belts in all standard EP constructions? We supply FRAS belts in EP200 to EP500 as standard. Other constructions are available on inquiry with appropriate lead time.
What documentation do you provide with FRAS belts? Material test certificate, drum friction test report, electrical resistance test report, and dimensional inspection report. Specific certification documents (AS 4606, SANS 971, etc.) depend on which standard was tested.