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Tramp Oil Removal2023-05-18T11:58:57+00:00

Tramp Oil Removal using Zebra Skimmers and Coalescers

Tramp oil originates as lubrication oil seeps out from the slide-ways and washes into the coolant mixture, or as the protective film with which the steel supplier coats the bar stock to prevent rusting, or as hydraulic oil leaks. In extreme cases it can be seen as a film or skin on the surface of the coolant or as floating specks of oil. It is considered a contaminant and a potential pollutant if not dealt with properly.

What is tramp oil?

Tramp oil refers to oils and other contaminants that can accumulate in metalworking fluid systems and is usually composed of cutting oils, lubricants, coolants, and other substances used in metalworking processes. The oils can come from various sources, such as machine tool sumps, parts washing systems, or leaky machinery. Tramp oil can negatively impact the performance of metalworking fluids by reducing their effectiveness, promoting bacterial growth, and leading to the formation of sludge. In order to maintain the quality of metalworking fluids, it is important to have it removed on a regular basis. This can be done using tramp oil skimmers, centrifuges, or other separation methods.

How Skimmers and Coalescers Function

Skimmers are used to separate the oils from the coolant. These are typically slowly rotating disks, tubes or belts that are partially submerged below the coolant level. As these moving parts rotate through the coolant, tramp oils cling to them and passes through a separator or wiper before returning to the coolant sump. Theses wipers also direct the tramp oil to a container where it is collected for disposal.

To remove tramp oils, Zebra Skimmers manufactures disktube, and belt skimmers as well as the Muscle™ coalescer that uses a floating oil skimmer for tramp oil removal from the surface of metalworking coolants.

Zebra skimmers are designed as simple, trouble-free, economic solutions for removing free floating and mechanically dispersed tramp oils from individual machine sumps. Based on gravity flow and coalescence, Zebras disc, tube and belt skimmers can reduce these oils to less than 1% in a single pass.

In the picture below we see a Zebra Belt Skimmer with the Diverter and lockjaw accessories mounted to a machine sump skimming coolant. With the attached diverter it is separating the oil and dispersing that into the bucket and returning clean coolant to the sump tank.

Belt Skimmer in action

The full line of skimmers extend the productive life of soluble oil, semi-synthetic and synthetic coolants, as well as the cutting tool. The  Zebra line of skimmers are backed by our standard 90-day warranty and is proudly manufactured in the United States.

Benefits of using Zebra Skimmers:

  • Most Inexpensive Way to Remove Oil from Coolant
  • Reduces Bacterial Growth and Foul Sump Odors
  • Prolongs Coolant Life, Reducing Raw Material Costs
  • Extends Tool Life and Improves Part Quality
  • Prevents Plugging of Spray Heads and Filters
  • Reduces Disposal Costs
  • Minimal Maintenance

Comparison data on skimmers

wdt_ID Tube Skimmers Belt Skimmers Disk Skimmers Z17 Coalescer
1 Tramp Oil Ratings: 1 qt/hr Tramp Oil Ratings: 1" - 1 gallon/hr Tramp Oil Ratings: 1+ gallons/hr Tramp Oil Ratings: 3 gallons/minute
2 max fluid temp 90°F (30°C) max fluid temp poly belt 40-80°F (4-27°C) Stainless Steel belt 60-212°F (15-100°C) max fluid temp standard disk 80°F (27°C) High temp disk 212°F (100C) max fluid temp 90°F (30°C)
3 Use on sumps with limited access Use on sumps with limited access and heavy tramp oil loads Use on sumps with larger access heavy tramp oil loads Use on sumps with very heavy tramp oil loads that require extra filtration


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