Guide
Understanding varnish
Where deposits come from, why a finer filter does not remove them, and what MPC ΔE actually measures.
Technical library
Reference material, not marketing material.
The standards, tables and procedures we work to. If you want to run your own programme without us, everything you need to start is on this page.
01. Standards
The test methods behind every Malina report.
Every figure we publish is traceable to a named method. Where a client's OEM specifies a different method for the same property, the OEM method governs.
| Method | Property | What it tells you |
|---|---|---|
| ASTM D7843 | MPC varnish potential | The deposit-forming tendency of the fluid, reported as a ΔE colour value. |
| ASTM D2272 | RPVOT | Remaining oxidative life, compared against the new-oil baseline for that product. |
| ISO 4406 | Particle count | Solid contamination as a three-part code at 4, 6 and 14 microns. |
| ASTM D6304 | Water content | Total water by Karl Fischer titration, in parts per million. |
| ASTM D445 | Kinematic viscosity | Whether the fluid still matches its grade, and whether it has been mixed or oxidised. |
| ASTM D664 | Acid number | Acidic degradation by-products accumulating in the charge. |
| ASTM D7414 / D7415 | FTIR oxidation, sulphation | Chemical fingerprint of degradation and contamination. |
| ASTM D5185 | Elemental analysis | Wear metals, additive elements and contaminant metals by ICP. |
| ASTM D6971 | Antioxidant reserve | Remaining hindered phenol and aromatic amine antioxidants by voltammetry. |
| ISO 3722 / 3171 | Sampling practice | How a representative sample must be drawn for any of the above to mean anything. |
02. Reading a cleanliness code
ISO 4406 in one table.
The code is three numbers, particles ≥4 µm, ≥6 µm and ≥14 µm, and each number is a range code, not a count. One code step is a doubling of contamination.
| Code | More than | Up to and including |
|---|---|---|
| 22 | 20 000 | 40 000 |
| 21 | 10 000 | 20 000 |
| 20 | 5 000 | 10 000 |
| 19 | 2 500 | 5 000 |
| 18 | 1 300 | 2 500 |
| 17 | 640 | 1 300 |
| 16 | 320 | 640 |
| 15 | 160 | 320 |
| 14 | 80 | 160 |
| 13 | 40 | 80 |
| 12 | 20 | 40 |
| 11 | 10 | 20 |
Typical target codes by system
| System | Target code |
|---|---|
| Servo valve hydraulics | 15/13/10 |
| Proportional valve hydraulics | 16/14/11 |
| Turbine lube oil | 16/14/11 |
| General industrial hydraulics | 18/16/13 |
| Gearboxes | 18/16/13 |
| Low-pressure circulating systems | 19/17/14 |
A system running four codes above target is carrying roughly sixteen times the intended particle load. That is the difference between a pump reaching design life and reaching half of it.
03. Sampling
A bad sample is worse than no sample.
It costs the same to analyse and it produces a number your team will act on. Most disputed oil analysis results trace back to how the sample was drawn.
Rule 01
Sample from a live, turbulent line
Draw from a flowing line upstream of the filter, not from the bottom of a settled reservoir. A drain-valve sample tells you about the sump, not the system.
Rule 02
Flush the port first
Discard several times the dead volume of the sample valve and tubing before filling the bottle. The material sitting in a sample port is not representative of anything.
Rule 03
Sample at operating temperature
Take the sample with the machine at normal running temperature and load. Cold oil holds water and degradation products differently, and the result will not compare with previous data.
Rule 04
Use a clean bottle and keep it closed
Use certified-clean bottles, open them for as short a time as possible, and never sample in the rain or in a dust cloud. The bottle can easily be dirtier than the oil.
Rule 05
Sample the same point every time
Trending only works if the sample is drawn from the same location, the same way, at the same operating condition. Label the point permanently and record it.
Second opinion
Send us a report you are unsure about.
We will read it against these standards and tell you what it says, at no cost and with no obligation.