Oil Acid Number (TAN) Trend Tracker
Log total acid number readings, see the wear trend and get a projected date when the 2 mg KOH/g limit will be reached.
Readings stay in your browser (localStorage) โ nothing is uploaded.
Straight-line (least-squares) extrapolation of your logged readings to the 2 mg KOH/g alarm threshold (warning at 1.5 mg KOH/g). A low Rยฒ means the trend is noisy โ log more readings before trusting the projection.
Field notes from maintenance practice
TAN tells you the oil is dying, not the machine โ pair it with wear metals from the same sample. The right alarm depends on oil type: turbine oils condemn near 0.3โ0.4 above baseline, hydraulic oils near 2.0 absolute, EP gear oils start life already at 0.5+ because the additive package itself is acidic. Always log against the new-oil baseline of the exact product in the machine. The default action limit of 2 mg KOH/g comes from the widespread condemnation guideline of TAN reaching baseline + 1.0 mg KOH/g, or an absolute ~2.0 for R&O/hydraulic oils (check your oil supplier's limit table); adjust it if your OEM or procedure specifies otherwise.
Linear extrapolation is honest only when the Rยฒ is decent (โฅ 0.7) and degradation is steady. Oxidation is autocatalytic: acids catalyse further oxidation, so TAN curves bend upward near the end โ a projection from early-life points will flatter the oil. If the last reading jumps far off the line, re-measure before believing it โ measurement technique drifts too.
Sources & references
- ASTM D974 / D664 โ acid number test methods
- ASTM D4378 โ in-service monitoring of mineral turbine oils
Trend screening only โ confirm with a proper inspection before running equipment to a projected limit.
Oil Acid Number (TAN) Trend Tracker for maintenance and reliability teams: Log total acid number readings, see the wear trend and get a projected date when the 2 mg KOH/g limit will be reached. Free, private (everything runs in your browser) and ready for daily plant use.
About Oil Acid Number (TAN) Trend Tracker
This tracker is a remaining-useful-life (RUL) estimator for total acid number. Log a dated reading whenever you measure; the tool fits a least-squares straight line through your history and projects when it will cross the 2 mg KOH/g action limit (warning at 1.5 mg KOH/g) โ turning scattered measurements into a forecast date you can plan parts and downtime around.
How to use Oil Acid Number (TAN) Trend Tracker
- 1Enter each dated measurement as you take it โ readings persist in your browser between visits.
- 2Adjust the alarm (and warning) threshold to your OEM or procedure limit if it differs from the default.
- 3Read the fitted trend, Rยฒ, days-to-alarm and the projected date โ then plan parts and downtime around that date.
Why use Oil Acid Number (TAN) Trend Tracker?
- โLog total acid number readings, see the wear trend and get a projected date when the 2 mg KOH/g limit will be reached โ computed instantly with the standard formula
- โ100% free and unlimited, with no sign-up, login or paywall
- โRuns entirely in your browser โ readings and asset data never leave your device
- โNiche-specific defaults and thresholds for total acid number, traceable to the cited standards
Frequently asked questions
What limit should trigger action for total acid number?+
The widely used limit is 2 mg KOH/g (the widespread condemnation guideline of TAN reaching baseline + 1.0 mg KOH/g, or an absolute ~2.0 for R&O/hydraulic oils (check your oil supplier's limit table)). Set a warning at 1.5 mg KOH/g so parts and labour are ready before the alarm. Your OEM manual or internal procedure overrides the generic figure.
My new oil already shows TAN 0.8 โ is it bad oil?+
No โ many additive packages (especially EP gear oils and engine oils) are intentionally acidic when fresh. That is why limits are written as 'baseline + ฮ' rather than absolutes. Get a fresh-oil sample analysed once, record it as your baseline, and condemn on the rise above that baseline, typically +1.0 mg KOH/g for industrial oils.
How many readings before the projection is trustworthy?+
At least 4โ6 spread over a meaningful fraction of the asset's life, with a fit Rยฒ of about 0.7 or better. Two points always make a perfect line โ that is curve fitting, not condition monitoring. Keep measurement conditions (load, temperature, location) consistent.
Is straight-line extrapolation valid for wear?+
It is the standard first approximation for steady-state degradation, and it is deliberately conservative to act on. Many failure modes accelerate near the end (bathtub curve), so treat the projected date as the latest acceptable intervention date, not a promise.
Where is my logged data stored?+
Entirely in your browser's localStorage on this device โ nothing is uploaded to any server. Export or note critical values elsewhere if you need a permanent maintenance record shared across a team.
Embed Oil Acid Number (TAN) Trend Tracker on your website
Want Oil Acid Number (TAN) Trend Trackeron your own site? Paste this snippet into any HTML page โ it's free, with no API key or sign-up. The tool loads in an iframe and keeps working exactly as it does here.
<iframe src="https://tooljolt.com/tools/oil-acid-number-trend-tracker" width="100%" height="640" style="border:1px solid #e5e7eb;border-radius:12px;max-width:680px" title="Oil Acid Number (TAN) Trend Tracker โ ToolJolt" loading="lazy"></iframe>Related tools
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