The Importance of Cleanliness in Water/Glycol Hydraulic Fluids and Challenges with Particle Counting Hydraulic systems rely heavily on fluid cleanliness to ensure efficiency, longevity, and reliability. Among the various hydraulic fluids used in industrial applications, water/glycol-based hydraulic fluids stand out for their unique properties, particularly their excellent fire resistance and ability to operate in harsh environments. However, maintaining the cleanliness of these fluids poses distinct challenges, especially when it comes to particle counting—a critical aspect of monitoring fluid health.
Why Cleanliness Matters in Water/Glycol Fluids
Water/glycol hydraulic fluids are commonly used in industries such as steelmaking, mining, and aviation, where fire safety and thermal stability are paramount. The cleanliness of these fluids is crucial for several reasons. Contaminants like dirt, wear particles, and corrosion products can damage hydraulic components, causing premature wear of pumps, valves, and seals. Particulates can influence the chemical stability of water/glycol fluids, potentially compromising their fire-resistant properties.
Given the criticality of cleanliness, regular monitoring of water/glycol fluids is essential. However, these fluids present unique challenges that make traditional particle counting methods less effective.
Challenges in Particle Counting for Water/Glycol Fluids
Particle counting is one of the most effective ways to assess hydraulic fluid cleanliness. However, water/glycol fluids complicate this process due to their composition and behavior. Water/glycol fluids typically contain 35-50% water, which affects the optical properties of the fluid. Optical particle counters can misidentify water droplets as solid particles, leading to inflated particle counts and inaccurate cleanliness assessments.
To overcome these challenges, specialized methods and instruments are needed for accurate particle counting in water/glycol fluids. The standard ASTM D7647-21 specifically addresses the optical particle counting of hydraulic fluids containing water. By masking the influence of water droplets and soft particles, it provides a more reliable particle count. Automated particle counters like the CINRG CS-APC-3 and CS-APC-22M are designed to handle fluids with high water content. They ensure accurate counts by masking the water present in the sample.
Particle Counting Method for Water/Glycol Fluids
CINRG has developed a straight-foward method for accurate particle counting of water/glycol based fire-resistant hydraulic fluids. This method substitues the standard isopropanol/toluene solvent for EGBE which has better water masking properties.
Sample Type Water/Glycol based Fire-Resistant Fluids (i.e. Houghton Houghto-Safe 620) typically have between 35% and 45% water
Materials Dilution Solvent - Ethylene glycol butyl ether (2-Butoxyethanol) or DPnP (let settle for 12 hours)
Procedure
- Set stir speed to 6, using a minimum mixing time of 1 minute.
- Add 5 ml of sample to sample cup [sample:solvent] [1:5].
- Run samples using standard processing.
- If sample fails, reprocess adding only 1ml of sample to sample cup [sample:solvent] [1:29].
Water/glycol hydraulic fluids are indispensable in many industries, but their unique composition requires extra attention to cleanliness and fluid monitoring. Accurate particle counting is a cornerstone of fluid health management, but traditional methods often fall short when dealing with these complex fluids.
By adopting standards like ASTM D7647 and using advanced particle counters tailored to water/glycol fluids, industries can ensure accurate cleanliness assessments. This not only extends equipment life but also enhances operational reliability and safety, particularly in high-stakes environments where fire resistance and performance are non-negotiable. As hydraulic systems evolve, so too must our approaches to maintaining their vital fluids.