Pressure DSC Oxidation Induction Time Analyzer

What is the Pressure DSC Oxidation Induction Time Analyzer?

A pressure differential scanning calorimeter measures the onset of oxidation of a small oil sample held isothermally in oxygen at elevated pressure. It gives oxidation induction time in minutes, using about 3 mg of sample, and is widely used for engine oil and additive research under ASTM D6186.

Overview

A 3 mg sample in an open aluminum pan is placed in a DSC cell, which is pressurized with oxygen to 3.5 MPa and heated rapidly to an isothermal temperature, commonly 130 to 210 °C. The instrument compares heat flow between the sample and a reference pan. When the antioxidant is consumed, oxidation begins and the exotherm appears. The oxidation induction time is the interval from reaching temperature to the onset of the exotherm, determined by the tangent method. Because samples are tiny and tests last minutes to an hour, PDSC is convenient for screening many additive blends, and high-pressure cells allow use with thermal analysis software. It needs careful pan preparation and calibration with indium, since sample mass and pan surface affect results.

How does it work?

Oxidation converts hydrocarbons into acids, sludge and varnish through free-radical chain reactions that speed up once inhibitors are consumed. Accelerated tests expose an oil sample to oxygen or air at elevated temperature, often with copper and iron catalyst wire and water, and monitor the reaction. In rotating pressure vessel tests, a sealed bomb containing oil, water and a copper coil is charged with oxygen at 620 kPa, heated to 150 °C and rotated, and the time until pressure falls by 175 kPa is recorded. Turbine oil tests run for thousands of hours and measure time to an acid number of 2.0 mg KOH/g. Differential scanning calorimetry detects the exothermic onset under oxygen pressure, and thin-film methods measure oxygen uptake. Induction time reflects the oil's remaining antioxidant reserve.

What are the key features?

• High-pressure DSC cell up to 7 MPa oxygen
• Isothermal temperature up to 400 °C
• Sample size of about 3 mg
• Automatic onset calculation by tangent method
• Optional autosampler for unattended runs

What are the technical specifications?

A typical pressure dsc oxidation induction time analyzer configuration offers pressure range of Up to 7 MPa (3.5 MPa typical), temperature range of Ambient to 600 °C, isothermal temperature of 130–210 °C typical, sample mass of ≈ 3 ± 0.2 mg, heat-flow sensitivity of ≈ 0.1 µW and temperature accuracy of ± 0.1 °C. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Pressure DSC Oxidation Induction Time Analyzer is used in additive screening in engine oils, grease and lubricant oxidation research and polymer and fat stability studies. Across the wider Oxidation Stability class, laboratories also deploy it for turbine oil life assessment, antioxidant additive development and hydraulic oil QC.

Which standards and certifications apply?

Relevant standards and methods include ASTM D2272, ASTM D943, ASTM D6186, ASTM D4742, ASTM D7545, IEC 61125, ASTM D2440 and ISO 4263. Certification candidates for this model are CE and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Oxidation tests use pressurized oxygen and heated oil, so safety is the first consideration. Use oxygen-compatible, oil-free regulators and fittings, pressure relief devices and guarding, and keep the area ventilated and free of grease. Clean glassware and bombs thoroughly, since contaminants alter induction time. Prepare catalyst coils exactly per the method, using specified copper wire and polishing. Check bath temperature uniformity and sensor calibration, and test with a reference oil of known RPVOT value on a schedule. Verify leak tightness before each run and keep logs of repeat results. Dispose of used oil and water according to local rules.

How do I select the right Pressure DSC Oxidation Induction Time Analyzer?

Choose pressure DSC when sample volume is limited or you must screen many formulations quickly. It is less suited to routine acceptance testing. Specify maximum pressure, temperature range, sample pan type, autosampler and software for oxidation induction calculation. Calibrate against indium and use reference oils for qualification.

How does it compare with other Oxidation Stability variants?

Select the test that your specification names. Turbine and hydraulic oil specifications commonly call for rotating pressure vessel oxidation test (RPVOT) and the long-duration turbine oil stability test. Formulators developing additives prefer faster methods such as pressure differential scanning calorimetry or thin-film oxygen uptake, which need small samples. Insulating oil producers follow IEC 61125 or ASTM D2440. Consider the number of positions, since tests run for hours or weeks, and the degree of automation including pressure logging, endpoint detection and report generation. Check bath temperature uniformity, safety features for oxygen and pressure, and supply of glass sample containers, catalyst coil and test bombs. In the RFQ, list methods, number of simultaneous tests and sample volumes.