Diana 701 Next-Generation Metal Multi-Plug – Robust Alternative to Glass Sensors with Convincing ASTM D86 Performance

Accurate vapor temperature measurement is a critical requirement for the distillation analysis of petroleum products. Even minor inaccuracies can result in deviations in the reported distillation curve, potentially leading to incorrect product characterization and non-compliance with regulatory specifications. Therefore, the performance and reliability of the temperature measurement system are fundamental to both routine laboratory analysis and quality control.

Historically, many distillation test methods specified the use of mercury-in-glass thermometers with defined dimensional and thermal characteristics. Due to increasing safety and environmental requirements, these have largely been replaced in modern automated distillation instruments by electronic temperature sensors based on platinum resistance thermometers (Pt100).

Glass-encapsulated Pt100 sensors have traditionally been used because their thermal behavior can closely reproduce that of the historical reference thermometers. However, the mechanical fragility of glass remains a disadvantage in routine laboratory operation, where accidental breakage can pose a safety risk to the operator, cause instrument downtime, and require sensor replacement.

To overcome this limitation, the Diana 701 can be equipped with a metal vapor temperature sensor integrated with the flask holder in a compact and convenient multi-plug. Its metal construction is designed to reduce the risk of breakage while maintaining the measurement performance required for ASTM D86 analysis.
In this study, the influence of sensor materials on measurement performance was assessed by comparing metal and glass Pt100 sensors using gasoline, jet fuel, and diesel samples from ASTM proficiency testing programs. The results demonstrate comparable measurement performance of the two sensor variants under routine testing conditions.