RPVOT (RBOT) Petroleum Oxidation Stability Tester

Oxidation Stability Testing Equipment

Professional testing systems for determining oxidation stability of steam turbine oils, inhibited mineral insulating oils, and gasoline automotive engine oils. These systems utilize severe oxidation conditions to rapidly evaluate oxidation stability in both new and in-service petroleum oils through standardized rotating pressure vessel methods.

Available Testing Methods

• Rotating Pressure Vessel Oxidation Test (RPVOT/RBOT) for steam turbine oils and mineral insulating oils
• Thin Film Oxidation Uptake Test (TFOUT) for gasoline automotive engine oils

Test Methodology

The RPVOT (RBOT) procedure oxidizes samples in the presence of water and a copper catalyst within a stainless steel pressure vessel under an initial pressure of 90psi (620kPa). Pressure inside the vessel is recorded electronically or mechanically while the vessel rotates at 100rpm at constant temperature. The oxidation stability of the sample is determined by measuring the time required for a specified drop in pressure. The TFOUT method represents a variation of the RPVOT (RBOT) procedure specifically designed for gasoline automotive engine oils.

Oxidation Pressure Vessel

Polished stainless steel construction withstands working pressure of 500psi (3450kPa) per ASTM specifications. The vessel connects to pressure recorder or rotary transducer and rotates on magnetic carriage in RBOT bath. Stainless steel construction ensures proper rate of heat transfer.

Construction and Components

• Pressure vessel body, cap, and stem with inlet needle valve in accordance with ASTM specifications
• Holds one borosilicate glass sample container between two PTFE discs
• Hand-tightening closure ring seals cap to pressure vessel body
• Chrome plated steel closure ring
• Includes PTFE fluorocarbon wear disc and sample container cover disc
• Can be converted for TFOUT testing using aluminum insert (K70092)

Oxidata® Pressure Measurement System

Complete electronic measurement systems plot pressure versus time and temperature in RPVOT (RBOT) and TFOUT testing. Each system includes transducers, bomb couplings, RTD probe assembly, multiplexer, data acquisition card, software, and mounting and connecting hardware. Systems are available in two, three, and four pressure vessel configurations, with additional channels expandable to a total of twelve pressure and four temperature channels.

Software Features

• On-line, real time monitoring of up to twelve samples simultaneously with results plotting directly to screen for instant monitoring or printout
• Menu options for RPVOT (RBOT) or TFOUT testing, as well as other ASTM fuel and lubricant oxidation tests
• Programmable automatic end point detection with graphical and tabular representation
• Each channel configurable and operable independently with different start/stop times and different ASTM test methods
• Zoom feature allows magnification of any plot sector on any channel for detailed study
• Monitors and reports temperatures of up to four baths simultaneously using accessory RTD's, calculates and displays average temperature for each bath
• Exports data to spreadsheet programs such as Microsoft Excel®, Lotus 1-2-3®, etc.
• Temperature and pressure calibration capability
• Data saved directly to hard drive during testing to prevent loss of valuable data
• Operates in Windows® 2000 or higher
• Simple upgrade from existing Koehler data acquisition systems

Included Accessories

• Rotary transducers (connects directly to bomb)
• Data acquisition box with USB interface
• Oxidata® software
• Multiplexer
• RTD probe assembly (1)
• Mounting bracket for bath
• Connecting cables and hardware

Computer Requirements

Electronic Pressure Measurement System Models

Oxidation Baths

Constant temperature baths rotate oxidation pressure vessels at 100rpm at an angle of 30° in accordance with ASTM specifications. Includes drive system and oil bath with electronic solid state temperature control. Meets ASTM requirements for heat transfer capability and temperature control precision.

Bath Construction and Operation

A convenient carriage arrangement allows oxidation vessels to be inserted quickly and securely in the drive system. A strong magnet holds the vessel in place while locating pins in the carriage engage the base of the vessel. PTFE guides support the pressure vessel stem for added stability. If the vessel becomes obstructed for any reason, the magnetic carriage releases it to prevent damage.

A chain and sprocket drive system powered by a heavy duty capacitor start motor rotates the vessel carriages at 100rpm. Drive shafts ride on PTFE fluorocarbon bearings which provide extended service and are compatible with silicone heat transfer fluids and other types of bath oils.

Bath temperature is controlled within ASTM specified limits by an electronic solid state controller with °C/°F switchable digital setpoint and display. Overtemperature protection is provided by a built-in limit control that automatically interrupts power to the bath when bath liquid temperature exceeds 16.7°C (30°F) above the temperature setting or 177°C (350°F). Power must then be manually restored by the operator after checking the cause of the problem.

Pressure vessel carriage vanes circulate the bath oil during testing to ensure temperature uniformity. An auxiliary stirrer can be operated between tests to prevent sludging of non-silicone bath oils. The bath interior is constructed of welded stainless steel and is fully insulated. A hinged section of the bath cover provides easy access to the vessel carriages. Vapor barriers in the cover close around the vessel stems to contain vapors from the hot bath medium. A chemical resistant polyurethane finish protects the bath exterior and control cabinet.

Specifications

Bath Models

Pressure Recorder

Records pressure inside oxidation bomb on 24-hour charts. Range 0 to 200psi, accurate to within 2% of scale range, 24-hour spring wound chart movement. Housed in a finished metal case. Includes cartridge pen. Conforms to ASTM D2112, D2272, D4742 and IP 229 specifications.

Catalysts

Copper Catalyst for RPVOT (RBOT) Method