The Problem Oil Causes on Standard Belts
Standard conveyor belt covers are made from SBR (styrene-butadiene rubber) or natural rubber compounds. These materials swell, soften, and degrade when exposed to petroleum-based oils, greases, and hydrocarbons. A standard belt in an oil-contaminated environment will show cover swelling, surface tackiness, delamination between cover and carcass, and eventually structural failure β often much faster than normal wear would cause.
Oil-resistant belts use NBR (nitrile-butadiene rubber) cover compounds that resist swelling and degradation in oil and grease environments.
Where Oil Contamination Occurs on Conveyors
Oil gets onto conveyor belts from several sources:
Crusher and screen lubrication. Jaw crushers, cone crushers, and vibrating screens use oil lubrication systems. Leaks from bearings and gearboxes can drip onto belts running beneath the equipment.
Drive pulley lubrication. Conveyor drive gearboxes can leak oil onto the belt if poorly maintained.
Material being conveyed. Some materials contain oil β oil sands, oil-bearing shale, food processing waste, some industrial by-products.
Hydraulic fluid leaks. Mobile mining equipment and hydraulic systems on conveyors can leak hydraulic fluid onto the belt.
Food and agricultural applications. Vegetable oils and animal fats from food processing adhere to standard belts and cause the same swelling degradation as petroleum products.
Side-by-Side Comparison
| Property | Standard Belt (SBR/NR) | Oil-Resistant Belt (NBR) |
|---|---|---|
| Resistance to petroleum oils | Poor β swells and degrades | Good β resists swelling |
| Resistance to vegetable/animal fats | Poor | Good |
| Abrasion resistance | Full M24/N17 grades | Comparable β slight reduction possible |
| Low-temperature flexibility | Good (NR compound) | Moderate β NBR is stiffer at low temperatures |
| Cost | Standard | Moderately higher |
| Suitable for oily material conveying | No | Yes |
| Available cover grades | Full range | M24 equivalent (OR grade per DIN) |
DIN 22102 defines the oil-resistant cover as Grade OR (Oil Resistant). Some standards use Grade G for similar properties.
How to Assess Whether You Need Oil-Resistant Belt
Check for evidence of oil contact. Look at your current belt surface. If it has swollen areas, tacky patches, or sections where the cover feels softer than new belt, oil exposure is already occurring.
Identify oil sources. Walk the conveyor and identify all potential oil sources above and alongside the belt. Crusher lubrication, gearbox vents, hydraulic lines. Even occasional oil drip from a leaking bearing can cause localized degradation that creates a weak point.
Consider the material. If the material itself contains hydrocarbons (oil sand, certain ores from zones with petroleum residues), standard belt is not appropriate.
Evaluate frequency and severity. Occasional light oil contact may not justify the cost of full OR grade belt. Sustained oil exposure from a leaking system absolutely does.
Limitations of Oil-Resistant Belts
NBR is stiffer at low temperatures. In cold climate operations (below -10Β°C), NBR covers are stiffer than SBR or NR compounds. For Siberian or Andean operations with significant oil contamination, discuss compound options with your supplier β cold-flex AND oil-resistant is achievable but requires specific formulation.
Oil-resistant doesn't mean oil-proof. NBR resists swelling in oil but it's not completely immune. Sustained immersion in concentrated petroleum would still cause some degradation. The compound handles operational oil contamination β drips, splashes, contact with oily material β not prolonged submersion.
Not for all chemicals. NBR resists petroleum-based oils and greases well. It does not resist all chemicals. For specific chemical environments, consult us with the chemical identity and concentration.
Frequently Asked Questions
My crusher lubricant leaks occasionally onto the belt. Do I need oil-resistant belt for the whole conveyor? Not necessarily. If the leak is localized and infrequent, fixing the leak source is the first priority. If the leak cannot be fully eliminated, consider OR grade belt for the section running beneath the crusher β you don't have to specify it for the entire conveyor length.
Is oil-resistant belt more expensive? Moderately. NBR compound costs more than standard SBR. The premium is typically 10β20% per meter versus standard M24. Whether this is justified depends on how rapidly your current belts are degrading from oil contact.
Can I use oil-resistant belt in food processing? OR grade belt (NBR compound) resists vegetable oils and animal fats, which makes it suitable from a material compatibility standpoint. However, food contact applications may also require food-grade certification, non-toxic compound verification, and specific cleaning chemical resistance. Contact us for food-grade belt specifications separately.