The Belt Skimmer Principle
Belt oil skimmers operate on a simple yet highly effective principle: oils and water don't mix, and oils have a natural tendency to adhere to certain materials. Belt skimmers exploit this physical property to continuously remove tramp oil from the surface of coolant sumps without removing the valuable coolant itself.
Video demonstration of a belt skimmer in operation
Components of a Belt Skimmer
A typical belt oil skimmer consists of several key components working together:
The Belt
The heart of the system is a continuous loop of material (polymer, steel, or cogged) that has an affinity for oil but not water. This belt extends down into the coolant sump where it contacts the floating tramp oil.
Drive Mechanism
A motor-driven pulley system moves the belt at a slow, continuous pace, typically 20-60 feet per minute, pulling the oil-coated belt out of the sump.
Wiper Blades
As the oil-coated belt exits the sump, it passes through wiper blades (scrapers) that remove the collected oil from the belt surface.
Collection Container
The removed oil flows into a collection container where it can be properly disposed of or recycled according to environmental regulations.
The Belt Skimming Process: Step by Step
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Surface Contact
The belt is positioned to make contact with the surface of the coolant where tramp oil floats.
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Oil Adhesion
As the belt moves through the surface layer, tramp oil adheres to the belt material due to its oleophilic (oil-attracting) properties.
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Oil Transport
The continuous movement of the belt carries the adhered oil up and out of the coolant sump.
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Oil Removal
The oil-laden belt passes through wiper blades that scrape the oil from the belt surface.
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Oil Collection
The removed oil flows down into a collection container for disposal or recycling.
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Belt Return
The cleaned belt returns to the coolant surface to collect more oil, creating a continuous cycle of oil removal.
Detailed diagram of the belt skimming process
Types of Belt Materials
Different belt materials are designed for specific applications and operating conditions:
| Belt Type | Material | Best For | Temperature Range | Oil Pickup Rate |
|---|---|---|---|---|
| Poly Belt | Polyurethane | General applications, light to medium oils | 32°F - 180°F | Up to 1 gallon/hour |
| Cogged Belt | Textured polymer | Medium to heavy oils, increased surface area | 32°F - 180°F | Up to 1.5 gallons/hour |
| Stainless Steel | 304/316 stainless steel | High temperature, harsh chemicals | 32°F - 600°F | Up to 1 gallon/hour |
Factors Affecting Belt Skimmer Performance
Several factors influence the efficiency and effectiveness of belt skimmers:
- Belt Speed: Slower speeds generally allow more oil to adhere to the belt, but reduce the volume of oil removed over time.
- Belt Material: Different materials have varying affinities for different types of oils.
- Belt Width: Wider belts can remove more oil but may not fit in smaller sumps.
- Oil Viscosity: Thicker oils adhere more readily to belts but may be more difficult to remove with wiper blades.
- Temperature: Higher temperatures can reduce oil viscosity, affecting adhesion to the belt.
- Wiper Blade Condition: Worn or improperly adjusted wiper blades reduce removal efficiency.
- Sump Design: The layout of the sump can affect how oil accumulates and how effectively the belt can contact it.
Installation Considerations
Proper installation is crucial for optimal belt skimmer performance:
Placement
Position the skimmer where tramp oil naturally accumulates, often in corners or areas with less turbulence.
Belt Depth
Ensure the belt extends just below the surface of the coolant, typically 1/4" to 1/2" deep.
Height Adjustment
Account for fluctuating coolant levels by installing the skimmer with height adjustment capabilities.
Power Supply
Ensure a stable power supply with appropriate electrical protection for the drive motor.
Maintenance Requirements
Belt skimmers require minimal maintenance, but regular attention to these areas ensures optimal performance:
- Wiper Blade Inspection: Check monthly for wear and proper contact with the belt.
- Belt Inspection: Examine quarterly for wear, damage, or stretching.
- Drive Mechanism: Lubricate as recommended by the manufacturer, typically every 6 months.
- Collection Container: Empty regularly to prevent overflow and maintain removal efficiency.
- General Cleaning: Wipe down external surfaces to prevent buildup of oil and contaminants.
Ready to Implement Belt Skimming in Your Facility?
Zebra Skimmers offers a complete range of belt oil skimmers designed for CNC machine applications.
