Oil and vibration analysis standards
On this page we summarise the ISO and ASTM standards most often referred to in oil and vibration analysis. For each one we give its scope, its current status and how it relates to our measurements. The standard texts and tables belong to ISO and ASTM. We summarise them in our own words and link to the official pages.
Vibration standards
| Standard | Scope | Status | Relevance to our measurements |
|---|---|---|---|
| ISO 20816-3 | Vibration assessment of industrial machines above 15 kW and 120–30,000 r/min, such as motors, fans and compressors | The 2022 edition is current. A new edition is in preparation. | Our reference framework for vibration level (RMS velocity). |
| ISO 10816-7 | Vibration assessment of rotodynamic pumps above 1 kW | The 2009 edition is current. | The standard we refer to for pumps. |
| ISO 10816-3 | Industrial machine vibration (older series) | Withdrawn. Replaced by ISO 20816-3. | Still often quoted in the field. |
| ISO 20816-1 | General principles for measuring and evaluating machine vibration | The 2016 edition is current. A new edition is in preparation. | The general framework. |
| ISO 13373-1 | Vibration measurement for condition monitoring, covering sensor choice and location, and continuous and periodic monitoring | The 2002 edition is current. | The basis of our approach to continuous monitoring and sensor location. |
Oil analysis standards
| Standard | Scope | Status | Relevance to our measurements |
|---|---|---|---|
| ISO 17359 | General procedure for setting up a machine condition monitoring programme | The 2018 edition is current. | The basis of our parameter, alarm and trend logic. |
| ISO 14830-1 | Guidance on condition monitoring by lubricant and hydraulic fluid analysis | The 2019 edition is current. | The overall framework for oil monitoring. |
| ISO 4406 | Solid particle contamination in fluids, expressed as a three-number code (e.g. 18/16/13) | The 2021 edition is current. | The online particle counter reports this code. |
| ISO 3448 | Viscosity grades for industrial lubricants (ISO VG) | The 1992 edition is current. | The starting point for reading measured viscosity. |
| ISO 3104 · ASTM D445 | Laboratory determination of kinematic viscosity (glass capillary viscometer) | Current. | A lab reference. The sensor uses a different method. |
| ISO 12937 · ASTM D6304 | Laboratory determination of water in oil by Karl Fischer | Current. | A lab reference. The sensor reports ppm and water activity. |
| ASTM D664 · ASTM D2896 | Acid number (TAN) and base number (TBN) | Current. | We do not measure these. They are lab tests. |
| ASTM D7720 | Statistical setting of alarm limits for in-service oil analysis data | Current. | It matches our alarm limit logic. |
ISO VG viscosity grades
The ISO VG number is the midpoint of the oil's kinematic viscosity at 40 °C in cSt. The permitted band is ±10%. The most common grades in turbines are VG 32, 46 and 68. For every grade and typical uses by equipment, see the ISO VG viscosity grade chart.
| Grade | Midpoint (40 °C) | Range (40 °C) |
|---|---|---|
| ISO VG 32 | 32 cSt | 28.8–35.2 cSt |
| ISO VG 46 | 46 cSt | 41.4–50.6 cSt |
| ISO VG 68 | 68 cSt | 61.2–74.8 cSt |
An in-line sensor measures viscosity at the oil's actual temperature. So the reading cannot be compared directly with the VG number on the label. What matters is the trend on the same machine.
How we set alarm limits
Public sources do not give one limit that fits every machine. For viscosity change, for example, different guides quote different percentages. So we set the limit from the machine's own baseline. First we record the readings in normal operation. We set the limit with a suitable margin above them and watch the trend. After an oil top-up we take the baseline again (US USACE EM 1110-2-1424).
Note: Our products make no claim of compliance with these standards. We cite them here as a reference framework. We checked the details against the official pages on 29 September 2026. We update this page as standards change.
How these standards apply to a machine is covered in the quote discussion.