Ensuring Hydraulic System Reliability with The Hydraulic Fluid Cleanliness Tester

Ensuring Hydraulic System Reliability with the Hydraulic Fluid Cleanliness Tester

Introduction
Contamination of hydraulic fluids by solid particles and entrained air is a leading cause of component wear, valve sticking, and unpredictable system behavior. The Hydraulic Fluid Cleanliness Tester from Changsha Friend Experimental Analysis Instrument Co., Ltd. provides precise, automated evaluation of fluid cleanliness in accordance with ISO 4406 and NAS 1638 standards. By delivering rapid, quantitative particle counts and air-bubble measurements, this instrument enables maintenance teams and fluid suppliers to detect contamination trends early and take corrective action before equipment failure occurs.

Testing Principles
This tester integrates two complementary measurement methods:

1. Optical Particle Counting

• Fluid is drawn through a precision flow-cell illuminated by a laser diode.

• A photodetector array counts and sizes particles in multiple size bins (e.g., > 4 µm, > 6 µm, > 14 µm, > 21 µm).

• Software converts raw counts into ISO 4406 cleanliness codes (e.g., 19/17/14) or NAS 1638 class numbers.

2. Entrained Air and Dissolved Gas Analysis

• Ultrasonic sensors measure acoustic attenuation and speed of sound, distinguishing entrained bubbles from liquid.

• The instrument reports air content in volume percent, helping to identify aeration and cavitation issues.

Key Design Features

• Automated Sample Handling
  A peristaltic sample pump draws fluid at a controlled flow rate (e.g., 50 mL/min), while built-in pre-filters prevent large debris from entering the optical cell.

• High-Resolution Optics
  Laser and photodetector modules detect particles down to 2 µm with size-bin accuracy of ±0.2 µm.

• Rapid Throughput
  Complete cleanliness and air tests finish in under 3 minutes, allowing multiple samples per shift.

• Intuitive Touchscreen Interface
  Operators select fluid type, standard, and reporting format; results and historical trends display on-screen and export via USB or Ethernet.

• LIMS Connectivity
  OPC-UA or Modbus support enables integration with plant databases and predictive-maintenance platforms.

Industry Applications

• Mobile Hydraulics: Excavators, loaders, and agricultural machinery rely on clean fluid to protect pumps and valves.

• Industrial Presses & Injection Molding: High-pressure systems demand tight cleanliness control to avoid downtime.

• Aerospace Ground Support: Hydraulic test stands and flight-control simulators use high-purity fluids for repeatable performance.

• Power Generation: Turbine governors and hydraulic governors require contamination-free oil to maintain grid stability.

Best Practices

1. Sample Collection
   Draw fluid from off-line sample ports under minimal agitation to avoid introducing air.

2. Pump Calibration
   Verify sample-pump flow rate monthly using a graduated cylinder.

3. Optics Cleaning
   Perform a “blank” run with filtered ISO Clean Oil every week to check for cell contamination.

4. Trend Monitoring
   Establish baseline cleanliness codes for each machine and investigate deviations ≥ 2 code steps.

By adopting this Hydraulic Fluid Cleanliness Tester, organizations can detect contamination before it leads to wear or failure, extend component life, and optimize maintenance intervals.