Varnish Removal / Oil Purification Oil Service

Technical Varnish Removal Solutions

Effective oil purification systems for degradation products

VEU-F Unit

Oil Cooling Technology

The VEU-F unit is installed on the bypass line of the oil tank.

The oil temperature is lowered, reducing the solubility of degradation products and causing them to precipitate. These products are then removed from the oil using special filter elements.

Cooling

Lowering oil temperature

Filtration

Special filter elements

VEU-F Varnish Elimination Unit
VEU-F Varnish Elimination Unit

VMU Unit

Ion Exchange Resins

Another effective solution is the use of ion exchange resin units - HYDAC VMU.

The VMU unit is also installed on the bypass line. Oil passes through the ion exchange resins.

Oil degradation products adhere to the resins due to an adhesive effect. The oil must be regularly tested for MPC value increases. A rise in MPC indicates the ion exchange element needs replacement.

Ion Exchange

Resin adheres contaminants

MPC Control

Regular oil analysis

Varnish Formation Theory

Key information on oil degradation issues

What is varnish?

Varnish is a byproduct of oil degradation and appears in various forms.

Forms of manifestation:

  • Paint-like layer on tank walls and pipelines
  • Sediment at the bottom of tanks
  • Buildup on valves and pump units
Black Brown Golden-yellow

How does varnish form?

Main causes of oil degradation products:

OxidationMain cause of oil aging – interaction with oxygen
ContaminantsForeign particles cause aging or catalytic effects
Temperature & PressureHigh parameters accelerate degradation. Electrostatic discharges break down additives

Why is this undesirable?

Oil degradation products form deposits leading to serious issues:

Clearance reductionLubrication gaps narrow, friction and heat increase
Component wearIncreased wear on bearings and moving parts
Valve malfunctionsVarnish in valves causes operational failures
Reduced efficiencyDeposits on heat exchangers and filters shorten service life

Oil Contamination & Equipment Aging

Laboratory studies show an alarming trend: more oil samples exhibit elevated aging values. Out of 3,584 analyzed samples, 614 had MPC values above the critical threshold. This means every sixth oil sample shows excessive aging, leading to component damage and operational failures.

3584Samples Analyzed
614Critical MPC Values
1 of 6Highly Aged Oils

Contamination Diagnostics: MPC Analysis (ASTM D7843)

MPC (Membrane Patch Colorimetry) indicates the oil's potential to form deposits. These deposits significantly increase equipment failure risk. Color measurement is performed on a 0.45 µm filter membrane.

  • Normal / Monitoring: < 15
  • Abnormal: 15 – 30
  • Critical: > 40
<15
15
20
30
40
50
>60
MPC (Membrane Patch Colorimetry) indicates the oil's potential to form deposits. These deposits significantly increase equipment failure risk. Color measurement is performed on a 0.45 µm filter membrane.
Tank Wall Deposits

Tank Wall Deposits

Bearing Varnish

Bearing Varnish

Rod Deposits

Rod Deposits

Solution: Operating Principle of the VEU-F Varnish Removal Unit

The VEU-F unit reliably removes oil aging products from lubricating and hydraulic oils in a bypass flow.

1

Oil Cooling

Converts polar aging products from dissolved to free state.

Oil Cooling
2

High-Efficiency Filtration

Removes sediment using polar cellulose. A two-stage filter element is used for large volumes.

High-Efficiency Filtration

Advantages & VEU-F Model Range

Extended oil life
Deposit prevention
Tank cleaning savings
Extended filter life

VEU-F-5/3

For tanks < 1000 L

VEU-F-5/3
  • Cost-effective auxiliary power unit
  • Maximum service life (5 bar differential pressure indicator)
  • 'Plug & Play' solution with mounting kit
  • Rapid MPC reduction < 10
  • Magnetic Quick Fix Plate (drill-free installation)

VEU-F...A / ...C

For tanks 1000 – 20000+ L

With heat exchanger

With heat exchanger

With compressor

With compressor

  • Fastest unit on the market
  • Guaranteed MPC reduction < 10 in one pass
  • Additional water and particle separation
  • Dimicron N15DM filter element with high dirt-holding capacity

Video Guide: Varnish Removal Unit Operation

Quick Video Navigation:

HYDAC Varnish Elimination Unit Overview

The HYDAC Varnish Elimination Unit (VEU-F-AU) is a cutting-edge solution for mineral oil regeneration. It is specifically designed to combat varnish (lacquer deposits) formed by high temperatures that contaminate hydraulic systems.

Quick Startup Guide
  1. Preparation: Place the unit on its brakes, connect hoses (original only), and ensure the chiller area is clear.
  2. Refilling: Check coolant level in the chiller (Fuchs Fricofin XT recommended, 20-40% concentration).
  3. Filter Replacement: Install elements into OLF and pre-filter housings. Remember to bleed air via the vent screw until oil appears.
  4. Startup: Connect power, turn on the isolator. PLC defaults to 15°C. Press Start.
  5. Calibration: The system automatically determines flow rate within 2-3 minutes to reach the set temperature.

Economics & ROI of Oil Cleaning System

VEU-F-60/1 in Turbine Lubrication (10,000 L)

Oil Service Life

6 → 10 years

1.7x Increase

Payback (ROI)

1–3 years

Full Payback

Annual Savings

11 022 €

On oil & maintenance

Baseline Data:
  • Oil Price: €2.50/L, Disposal: €0.50/L
  • Labor: €90/hr
  • Additional varnish costs (repair): €6,000
  • Oil replacement cost: €40,000
Benefits:
  • Reduced equipment downtime
  • Fewer oil changes
  • Lower component repair costs
  • Increased system reliability

Application Industries

Turbines
Turbines

Gas, steam, hydro

Hydropower
Hydropower

Hydro-turbine lubrication

Plastics
Plastics

Injection molding machines

Presses
Presses

Hydraulic presses

Paper
Paper

Calender hydraulics

Test Benches
Test Benches

Testing equipment

Case Studies: VEU-F Implementation Examples

Plastic Molding (Netstal Synergy 24000)

Plastic Molding (Netstal Synergy 24000)

Problem: MPC 31.8, oil age 3 years

Solution: VEU-F-5/3 on bypass line

Result: MPC reduced to 10 in 9 days. ROI after one oil change.

Plastic Molding (Netstal Synergy 24000)
Test Bench

Test Bench

Problem: Pump replacement due to deposits

Solution: VEU-F-5/3 after oil change

Result: 18 months deposit-free (MPC 4). Oil life extended 4x.

Gas Turbine

Gas Turbine

Problem: MPC >60, oil age 11 years, filter blockages

Solution: VEU-F 60/1 (1 L/min flow)

Result: MPC reduced to 10 in 30 days. ROI in 1 year.

Gas Turbine