Thin-Film Oxygen Uptake Tester (TFOUT)

What is the Thin-Film Oxygen Uptake Tester (TFOUT)?

A thin-film oxygen uptake tester heats a small oil sample mixed with catalyst and fuel oxidation products in a pressurized oxygen vessel at 160 °C, and records the time until oxygen pressure drops. It evaluates engine oil oxidation stability under ASTM D4742.

Overview

A 1.5 g oil sample is mixed with a catalyst of soluble metal naphthenates, water and fuel-derived oxidized nitrogen compounds, and placed in a glass container inside a pressure vessel. The vessel is charged with oxygen at 620 kPa and immersed in a bath at 160 °C while rotating at 100 rpm. The oil forms a thin film, increasing oxygen contact. Pressure first rises with heating, and then drops as oxygen is absorbed. The end point is the time at which pressure falls 175 kPa below the maximum. Results are reported in minutes and are used to rank passenger-car engine oils and to screen additive systems. The apparatus is similar to RPVOT hardware, and many laboratories use the same bath with modified settings.

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?

• Pressure vessel with glass sample container
• Bath at 160 °C with rotating holder
• Pressure transducer and automatic endpoint
• Uses small sample of about 1.5 g
• Compatible with catalyst and reagent supplies

What are the technical specifications?

A typical thin-film oxygen uptake tester (tfout) configuration offers test temperature of 160 ± 0.2 °C, initial oxygen pressure of 620 kPa, bomb rotation of 100 ± 5 rpm, sample mass of 1.5 ± 0.01 g, end point of 175 kPa drop from maximum and positions of 1–4. 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 Thin-Film Oxygen Uptake Tester (TFOUT) is used in passenger-car engine oil screening, additive treat-rate optimization and engine oil quality control. 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 Thin-Film Oxygen Uptake Tester (TFOUT)?

Select a TFOUT setup when you evaluate engine oils under ASTM D4742 or when sample quantities are limited. It shares hardware with RPVOT if configured. Specify temperature capability, number of vessels, catalyst supplies and whether dual RPVOT and TFOUT capability is required.

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.