23 April, 2017

The importance of fluid sampling and preventative maintenance in hydraulic hose systems

13 April, 2017

By Matt Fielder, Condition Monitoring Market Development Manager, Parker HFFE.


Safe and reliable hydraulic systems are about far more than correct hose selection. Dependable installations that do not suffer from costly downtime are typically subject to organised and structured preventive maintenance programmes. Indeed, the best approach to preventing hydraulic system failures is being proactive in terms of inspection, maintenance and troubleshooting. Here, expert support and services from locally-based organisations such as ParkerStore can be the key to achieving long-term reliability and maximum uptime.

The importance of fluid sampling

Among the critical tools in any reputable preventative maintenance programme for hydraulic hose systems is fluid sampling, a practice that can save both time and money. Fluid sampling is able to identify potential problems that cannot be detected by human senses, and could cause major hydraulic or lube oil system failures.

A sampling process such as Par-Test from ParkerStore represents a complete laboratory analysis performed on a small volume of fluid. Customers can quickly analyse the test results of an individual sample and/or look at trend analysis for up to five different samples. Two types of kit are available, for water base fluid analysis or petroleum base fluid analysis. For both types, the test kit includes a pre-cleaned glass bottle, mailing container with pre-addressed label and sample information data sheet (to be filled out by the end user). Reports include particle count, photomicrograph, spectrometric, viscosity and neutralisation analysis. In addition, the petroleum base fluid analysis determines if the water present is beyond the saturation of the fluid, as well as a Karl Fischer test to give an accurate measure of water concentration in the sample fluid (measured in ppm).

With regard to particle count, results are reported over six different particle size ranges to the ISO 4406:1999 standard. The counts are per millilitre of fluid and the reporting is cumulative, namely the particle count in the >4(c)µm row includes the number of particles greater than 6, 14, 21, 38 and 70(c) µm, as well as particles between 4 and 6(c) µm in size.

For the photomicrograph (photo analysis), a small volume of fluid (20 ml) is magnified 100 times, which allows a quick glance at the contamination present in the fluid. Each line of the graduated scale represents 20 µm in size, while the full colour photomicrograph helps identify particles which would otherwise be grouped by class.

Viscosity is a very important property of a fluid in terms of system performance. It expresses the internal friction between molecules in the fluid. Typically, a breakdown in viscosity will be seen as an increase. Both SSU at 100ŗF and cSt at 40ŗC are reported.

Concerning neutralisation analysis, this titration test measures the acid level of the sample fluid and is referred to as the Total Acid Number (TAN). The production of acidic material causes oxidation degradation or aging of most fluids. This activity is promoted by elevated temperatures, the presence of entrained metal particles and intimate contact with air. It is the rate of increase of the TAN during any given period that is significant, not just the absolute value.




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