Based on Viscosity and additives is the oil consistent with stated grade?
Yes
Yes, the viscosity is within 10% of 46 mm2/s. The additives of zinc and phosphorus seem consistent with ZDDP anti-wear additive, which is the most common hydraulic oil additive.
What contamination appears to be in the sample?
Dirt
Silicon and Aluminium in a 2:1 or 3:1 ratio suggests Aluminium silicates aka dirt. The ISO cleanliness code has increased by 4 fold on the larger >14 micron particles and there is visible debris, most likely related to this dirt present.
What type of wear does dirt / hard particles cause predominantly?
Abrasive / Cutting wear
Dirt leads to cutting / abrasive wear within systems when present. In hydraulics this could be wear to pumps or chrome plated rods.
Is there any abnormal wear occurring in this sample?
No there is no abnormal wear
There is no abnormal wear occurring despite the sample showing presence of solid contaminants.
Considering the sample is 100ml and the tank is 2000L, is it likely with 20,000 times more dirt than in this sample in the system no wear would occur?
Abrasive particles will always cause wear within the system unless removed.
Abrasive particles will cause wear, so it is unlikely the sample is representative owing to the normal wear metals. It is possible the sample was not taken correctly such as from the bottom of a tank rather than middle of the tank. Remember to be careful in these assumptions though that all the material in contact with the oil is metallic, as plastic and rubber components/seals wearing would also give this mix of flags of debris and high particle count. Hence it is often good to look at the sample to identify if the particles appear to be dirt/debris or if they also contain e.g. seal debris etc.
Which diagnosis appears most appropriate for this sample?
Resample, not a change
The advice to change the oil in this instance could be very costly for the client as this would mean 2000L of oil, potentially extra 500 to 1000L for flushing, the labour to drain the tank and also the lost production from having the system offline. Since we are not confident the sample was taken correctly, the best advice is to recommend resampling. If the contamination is confirmed to be representative then the next stage would be to recommend analysis of the filters to help identify this material and confirm if it is seal wear for instance.
