Diesel density testing
Hydrometer range, temperature measurement, correction principles, sample handling and interpretation limitations.
View diesel kit guidance →Technical resources
Use the right tool, at the right point, with the right evidence.
Practical guidance for density testing, rapid diesel screening, water-control applications and fuel-event documentation.
Core guidance
Start with the operating question.
Select the resource that matches the fuel type, test purpose and level of certainty required.
Petrol density testing
Safe field conditions, petrol hydrometer range, ventilation, static control and temperature-aware readings.
View petrol kit guidance →DensiTest workflow
Rapid diesel screening, required event evidence, photography, acceptance rules and laboratory escalation.
Explore DensiTest →Water contamination
Visible free water, condensation, ingress pathways, tank housekeeping and compatible AquaTrap applications.
Explore AquaTrap™ →Evidence checklist
Operator, vehicle or tank, supplier, GPS, timestamp, quantity, receipt, sample and test photographs.
View the FuelGuard method →Laboratory escalation
When field screening should stop the process and trigger retained samples, chain of custody and accredited analysis.
Request escalation guidance →Density fundamentals
A hydrometer reading is an observed value—not a complete conclusion.
Fuel density changes with temperature. The sample point, instrument range, reading technique and temperature correction all affect how the result should be interpreted.
- Use the correct hydrometer range for the fuel
- Ensure the instrument floats freely
- Read at the appropriate liquid meniscus
- Record the sample temperature
- Apply the relevant correction guidance
- Repeat unexpected readings with a representative sample
Important distinction
A field anomaly can justify stopping, quarantining or escalating fuel. It should not be represented as accredited proof of composition, adulteration or specification failure unless the appropriate laboratory analysis has confirmed it.
Good evidence practice
Make the result reproducible.
- Label the sample and retain its source details
- Photograph the test clearly and without obstruction
- Keep the original receipt and transaction evidence
- Record who performed the test and when
- Document any repeat test or supervisor review
- Preserve the sample when escalation is likely
Quick answers
Frequently asked technical questions.
Can a hydrometer prove that diesel is adulterated?
No. A density reading is a useful screening observation. An unusual result should trigger a repeat sample, review against the correct specification and, where required, accredited laboratory analysis.
Does DensiTest replace laboratory analysis?
No. DensiTest is intended as a rapid operational screening and evidence tool. Formal confirmation requires the appropriate laboratory method and chain of custody.
Can AquaTrap solve the source of water ingress?
AquaTrap can support selected free-water control applications, but the source of water ingress, tank condition and housekeeping problem must still be investigated and corrected.
Should every fleet refuel be tested?
The FuelGuard Fleet model is deliberately built around compulsory testing at every participating diesel refuelling event to create a consistent control and evidence trail.
Need guidance for a specific fuel, tank, fleet or dispute?
Send us the operating context and the question the test needs to answer.
Request Technical Advice