/ / 7 Best Transformer Oil Filtration Machines in 2025: Reviews & Buying

7 Best Transformer Oil Filtration Machines in 2025: Reviews & Buying Guide

After months of testing, comparing, and occasionally cursing at stubborn machines, I finally figured out which ones are worth your time—and which ones you should politely walk past. That’s why I’m sharing this guide: the 7 best transformer oil purifiers for 2025, broken down by type—dehydration, degassing, vacuum, multifunction, and more—so you can skip the trial-and-error phase and find the machine that actually fits your transformer, your oil, and your budget.

Here’s what you’ll get from each review:

  • Actual cleaning power: How low can it push the water ppm? Can it remove gases and tiny particles like it promises?
  • Capacity & compatibility: How much oil can it handle, and what voltages and oil types can it deal with?
  • Ease of operation: Is it plug-and-play, or will you need a PhD to get it running?
  • Running costs: How much juice does it suck, how often do you change filters, and what’s the total lifetime cost?
  • Reliability & support: Can you actually call someone when things go wrong? Real-world success stories from companies that rely on it.

1. Best Dehydration Transformer Oil Purifier

Enervac EHV Series Vacuum Dehydrator

Enervac EHV Series Vacuum Dehydrator

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Pros

  • Extremely efficient water removal (to <10 ppm)
  • Meets IEC 60422 & ASTM D-1533 dehydration standards
  • Reliable for high-voltage applications (up to 500kV)
  • Trusted by utilities across North America

Cons

  • Higher initial investment
  • Maintenance parts can be costly outside North America
ParameterValue
Flow rate6000 L/h
Final moisture≤10 ppm
Gas removal~80%
Particle≤1 μm
Voltage110–500 kV
MobilitySkid/Trailer

Enervac’s EHV series is a global benchmark for dehydration. I’ve seen it restore heavily humidified oil to IEC standards in just hours, which is crucial for preventing insulation failures.

Purification Performance

  • Moisture removal: ≤10 ppm
  • Dissolved gas removal: ~80% (partial degassing)
  • Particle filtration: 1–3 μm
  • Standards: IEC 60422, ASTM D-1533

Capacity & Flexibility

  • Flow rate: 600–6000 L/h
  • Voltage range: 110–500 kV
  • Oil compatibility: mineral oil, ester, synthetic
  • Mobility: skid or trailer-mounted

Ease of Use

  • Semi-automatic control panel
  • Built-in moisture sensors and alarms
  • Optional SCADA remote interface

Energy & Costs

  • Power: 25–45 kW depending on model
  • Consumables: filter 6–12 months, pump oil yearly
  • TCO: high upfront, long service life, low downtime

Brand & Reliability

  • Market leader since the 1970s
  • Clients: Hydro One, BC Hydro, Duke Energy
  • Lifespan: 10+ years with maintenance

After-Sales

  • North America: strong service network
  • Overseas: authorized distributors, longer lead time

Success Case

U.S. Midwest substation: water content reduced 45 ppm → 8 ppm, dielectric breakdown voltage improved 35%, emergency maintenance calls dropped 60%.

Use Cases

  • Power utilities, EPC contractors, transformer manufacturers
  • Large substations, humid/coastal regions
  • Oil: mineral, ester, synthetic

2. Best Degassing Transformer Oil Purifier

GlobeCore CMM-4 Degassing Unit

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Pros

  • High dissolved gas removal (>99%)
  • Ideal for high-voltage transformers up to 500 kV
  • Stable performance for long runtime

Cons

  • Requires trained operators
  • Higher energy consumption than small-scale units
ParameterValue
Flow rate3000 L/h
Water≤15 ppm
Gas removal≥99%
Particle3 μm
Voltage220–500 kV
Oil typesMineral, silicone
SetupFixed

GlobeCore’s CMM-4 excels at removing dissolved gases, critical for preventing dielectric failures in HV transformers. Utilities in Europe and Asia trust it for high-voltage substations.

Purification Performance

  • Water content: ≤15 ppm
  • Gas removal: ≥99%
  • Particle filtration: 3 μm
  • Standards: IEC / ASTM compliant

Capacity & Flexibility

  • Flow rate: 3000 L/h
  • Voltage: 220–500 kV
  • Oil types: mineral and silicone oils
  • Setup: fixed installation

Ease of Use

  • Semi- to fully automatic
  • Intelligent sensors with alarms
  • Supports remote monitoring

Energy & Costs

  • Power: 20–25 kW/h
  • Consumables: filter yearly
  • TCO: moderate, saves downtime costs

Brand & Reliability

  • Widely used in European HV projects
  • Continuous operation: 5000+ hrs

After-Sales

  • 18-month warranty
  • Global support network

Success Case

500 kV substation in Inner Mongolia: extended oil life by 3 years, no failures during peak load season.

Use Cases

  • HV substations 220–500 kV
  • National/utility-grade transformers

3. Best Multi-Functional Transformer Oil Purifier

ZYC Double Stage Multi-function Transformer Oil Purifier

ZYC Double Stage Multi-function Oil Purifier

  • Working vacuum: ≤133pa
  • Limited vacuum: ≤5pa
  • Working Pressure: ≤ 0.4MPa
  • Continuous working hours: ≥150 h
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Pros

  • Dehydration + degassing + particle removal
  • Flexible flow rates for different transformer sizes
  • Mobile trailer or skid options

Cons

  • Larger footprint
  • Higher upfront cost
ParameterValue
Flow rate3600 L/h
Water≤10 ppm
Gas removal≥98%
Particle1 μm
Voltage35–500 kV
Oil typesMulti
MobilityTrailer/Skid

For domestic large-scale applications, ZYC combines all necessary purification steps in one machine, reducing downtime and handling multiple oil types efficiently.

Purification Performance

  • Water ≤10 ppm
  • Gas removal ≥98%
  • Particle ≤1 μm
  • IEC / ASTM compliant

Capacity & Flexibility

  • Flow: 3600 L/h
  • Voltage: 35–500 kV
  • Oil types: mineral, silicone, synthetic
  • Mobility: trailer or skid-mounted

Ease of Use

  • Full automation
  • Smart alarms and optional remote monitoring

Energy & Costs

  • Power: 25–35 kW
  • Filter change: 6–12 months
  • TCO: higher upfront, saves by combining functions

Brand & Reliability

  • Used in domestic power grids
  • Continuous runtime 3000+ hrs

After-Sales

Service ItemDetails
1-Year Full Machine WarrantyAll units include a 12-month warranty, covering repair, replacement, and return for quality issues
Free On-Site InstallationOur technicians provide free installation after delivery, ensuring safe and proper setup
Free System CommissioningComplete system checks and performance tuning to ensure optimal operation
Free Operator TrainingHands-on or remote training sessions to ensure your staff can operate equipment independently
Long-Term Spare Parts SupplyWe guarantee the availability of original spare parts for long-term maintenance
Technical Support & TroubleshootingPhone, video, or on-site support for fast problem resolution and expert guidance

Success Case

Southeast Asian steel mill treated transformer and hydraulic oils simultaneously, reducing downtime by 40%.

Use Cases

  • Multi-purpose industrial and utility sites
  • Various transformer voltages
  • Multi-oil environments

4. Best Vacuum Transformer Oil Purifier

TYD Series Vacuum Dehydration Oil Purification System

TYD Series Vacuum Dehydration Oil Purification System

  • Working vacuum: -0.06~-0.095 Mpa
  • Working pressure: ≤ 0.3MPa
  • Power: 380V 50HZ(customized)
  • Noise: ≤65~80 dB(A) ( depend on the configuration )
  • Continuous working hours: ≥150 h
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Pros

  • Removes water down to 5 ppm or less, super clean for high-voltage transformers
  • Excellent gas removal (≥99%), keeps insulation healthy
  • Works continuously for long hours without breaking a sweat
  • Trusted by utilities handling 500 kV+ transformers worldwide

Cons

  • Higher upfront price
  • Requires trained operators for setup and maintenance
ParameterValue
Flow rate4000 L/h
Final moisture content≤5 ppm
Gas removal≥99%
Particle filtration1 μm
Voltage110–500 kV
Oil typesMineral, Silicone, Synthetic
MobilityFixed installation

It’s perfect for anyone handling ultra-high voltage transformers, where even a small amount of moisture or dissolved gas can cause significant headaches (and substantial repair bills). The vacuum system pulls water and gas out so efficiently, you almost feel like the machine is sucking the worries out of your workflow too.

Purification Performance (Key Metrics)

  • Moisture removal: ≤5 ppm final water content—seriously dry oil
  • Dissolved gas removal: ≥99%, even for tricky gases like CO₂ and H₂
  • Solid particle filtration: 1 μm precision, keeping oil spotless
  • Standards compliance: Fully compliant with IEC 60422 and ASTM D-1533

Capacity & Flexibility

  • Flow rate: 4000 L/h, suitable for large transformers
  • Voltage compatibility: 110–500 kV, so that it can handle both medium and ultra-high voltage units
  • Oil types: Mineral oils, silicone oils, and synthetic oils
  • Setup options: Fixed installation, designed for continuous industrial operation

Ease of Use

  • Automation: Fully automatic, with built-in sensors to adjust vacuum and temperature
  • Monitoring & alarms: Smart alarms for overpressure, low oil levels, or filter saturation
  • Remote access: Optional SCADA integration lets you check performance without even walking into the substation

Energy Consumption & Running Cost

  • Power usage: ~30–40 kW depending on the model
  • Consumables: Filter cartridges replaced every 6–12 months; vacuum pump oil annually
  • TCO: High upfront cost, but extremely low maintenance downtime, making it cost-effective in the long run

Brand & Reliability

  • Market reputation: Chinon’s Filtration brand has been an industry benchmark for decades
  • Major clients: Widely used in Europe, North America, and Asia for high-voltage transformers
  • Continuous operation: Machines easily run 5000+ hours per year without major issues

After-Sales Support

  • Warranty and service support available through Chinon’s global network
  • Spare parts are accessible worldwide, but shipping may take longer outside Europe

Success Case

In a German 500 kV substation, the ZY series purified transformer oil that had been sitting for years. The results were impressive:

  • Water content dropped from 35 ppm → 4 ppm
  • Gas levels reduced by 98%
  • The oil’s dielectric strength improved enough to postpone a costly transformer rebuild

Suitable Users / Scenarios / Oil Types

  • Users: Utility companies, transformer manufacturers, high-voltage maintenance teams
  • Scenarios: Ultra-high voltage substations (220–500 kV), critical industrial transformers
  • Oil Types: Mineral oil, silicone oil, synthetic insulating oils

5. Best Pressure Filtration Oil Purifier

TYA Series Vacuum Hydraulic Oil Filtration System (2)

TYA Vacuum Hydraulic Oil Filtration System

  • Working vacuum: -0.06~-0.095 Mpa
  • Working pressure: ≤ 0.3MPa
  • Power: 380V 50HZ(customized)
  • Noise: ≤65~80 dB(A) ( depend on the configuration )
  • Continuous working hours: ≥150 h
read more

6. Best Online Transformer Oil Purifier

ZYZ OLTC online oil purifier

ZYZ OLTC Online Oil Purifier

  • Online treatment for on-load tap changers
  • Flow: 800 L/h
  • Prevents shutdowns, used in domestic OLTC projects
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7. Best Multi-Oil Purification System

CMM-12A DEGASSING UNIT

GlobeCore Multi-Oil CMM-12 Universal Purifier

  • Treats mineral, silicone, and synthetic oils
  • Ideal for facilities with mixed oil types
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Comparison Table

TypeModelWater (ppm)Gas RemovalParticle (μm)Flow (L/h)VoltageOil TypesMobilityStandard
DehydrationEnervac EHV≤1080%1–3600–6000110–500 kVMineral/Ester/SyntheticSkid/TrailerIEC/ASTM
DegassingGlobeCore CMM-4≤15≥99%33000220–500 kVMineral/SiliconeFixedIEC/ASTM
Multi-FunctionZYC≤10≥98%1360035–500 kVMultiTrailer/SkidIEC/ASTM
VacuumMicafil MCF≤5≥99%14000110–500 kVMineral/SiliconeFixedIEC/ASTM
PressureHuen PL≤3080%3180035–220 kVMineralSkidIEC/AST