Coalescing separation technology efficiently removes oil contamination from cutting fluids, washing liquids and degreasing baths. Flow rate: 600 L/h, with no consumable filter media.
During machining, washing, degreasing and heat-treatment processes, cutting fluids, washing liquids, degreasing baths and quenching fluids are often contaminated by hydraulic oil, lubricating oil, rust-preventive oil and other tramp oils. The FRIESS SMT500 oil-water separator uses coalescing technology to continuously remove floating and dispersed oil, helping to reduce odour, foam and fluid-maintenance problems.
Process flow:
The SMT500 draws the oil-rich surface layer through a floating suction device. After the contaminated liquid enters the separator, fine oil droplets combine and grow within the coalescing medium, then rise to the surface. The separated oil leaves through the oil outlet, while the cleaned liquid returns to the customer’s tank through the return connection.
The separation tank contains a coalescing medium made of oleophilic polypropylene. With a specific surface area of 433 m²/m³, the medium provides an ideal surface on which small oil droplets collide and combine into larger droplets.
As the droplets grow, their buoyancy increases. Because oil is less dense than water, the enlarged droplets rise more quickly to the liquid surface, where the separated oil can be removed. The stronger the coalescing effect, the larger the droplets and the shorter their rise time.
| Time Required for an Oil Droplet to Rise 75 mm (3 in) | |
|---|---|
| Droplet Size (µm) | Rise Time |
| 300 | 12 seconds |
| 150 | 42 seconds |
| 60 | 4 min 12 sec |
| 30 | 17 min 24 sec |
| 15 | 1 h 8 min 54 sec |
| 5 | 10 h 2 min 9 sec |
The importance of droplet size is evident from the table. Stokes’ Law also shows why droplet size strongly affects the final rising velocity:
V = (2gr²)(Δd) / 9μ
g: gravitational acceleration
r: oil-droplet radius
Δd: density difference between water and oil
μ: water viscosity
Note: rising velocity increases in proportion to the square of the droplet radius.
Optional equipment: FRIESS FMF 240 magnetic filter
The FRIESS FMF 240/1 magnetic filtration system removes contaminating particles from coolant, cutting fluid, grinding oil and other process fluids. It is easy to use, efficient and reliable.
The SMT500 oil-water separator is designed for applications in which oil is dispersed or emulsified in the process liquid. Unlike a conventional skimmer, it operates in a bypass loop and is particularly suitable for oil that does not simply float on the surface.
Typical applications:
Conventional belt and disc skimmers remove only oil floating on the liquid surface. Through its coalescing medium, the SMT500 also captures fine oil droplets suspended in the liquid and can achieve a separation efficiency more than ten times higher than that of a conventional skimmer.
Q1: What is the difference between the SMT500 and the SMT-FB series?
The SMT-FB series offers higher capacities of 450–11,300 L/h and is intended for large central tanks. The compact SMT500 handles 600 L/h and can be installed directly beside or above a tank, making it suitable for individual machine tools and smaller washing systems.
Q2: Can the SMT500 treat alkaline washing liquids?
Yes. Its 304 stainless-steel housing and alkali-resistant coalescing medium are suitable for separating oil from alkaline and neutral washing liquids.
Q3: Does installation require compressed air?
Yes. The SMT500 uses an air-operated diaphragm pump and requires a compressed-air supply, typically 0.4–0.6 MPa. With no electrical contact at the liquid circuit, this design also supports safe operation in sensitive environments.
Q4: Can the system remove metal particles as well?
Yes. An optional FRIESS FMF 240 magnetic filter can be added to remove metal fines and magnetic particles together with the oil contamination.
Q5: How often does the unit require maintenance?
We recommend cleaning the coalescing medium approximately every six months, depending on the contamination load. Under normal operating conditions it has a long service life. The diaphragm-pump seals should be inspected periodically; overall maintenance costs are very low.
Beyond reducing costs, FRIESS oil skimmers, electrostatic oil cleaners, magnetic filters, coolant purification systems, oil-water separators and vacuum oil purifiers offer many additional benefits.
We will be pleased to help you identify the right solution.
