The Rolling Thin Film Oven (RTFO) accurately simulates the significant shortterm aging of binder in hotmix asphalt that occurs during production and paving operations. RTFO tests are a simple and effective way to determine the effect of heat and air on a moving film of asphalt binder. Values are derived from measurements of binder properties before and after conditioning in the oven. James Cox and Sons Rolling Thin Film Ovens are designed and manufactured in the USA, and feature a five-year manufacturer's warranty.
Test repeatability is directly related to the accuracy and stability of oven temperature and reproducibility of the thermal rise time. RTFO temperatures are controlled using a precision resistance temperature detector (RTD) sensor with extremely low thermal mass, allowing a thermal/electrical time constant measurable in seconds. The PID controller provides an accurate output signal, enabling stable closed-loop control. A unique suppression feature built into the controller allows very fast response time with minimal overshoot. An over-temperature safety cutoff feature is built-in. Actual and set point temperatures can be viewed simultaneously on the dual four-digit displays.
The MO-30 RTFO is supplied with a mechanical flow meter, moisture indicator, and air pressure gauge with regulator, ready for connection to a supply of clean, dry compressed air. The MO-32 RTFO has a digital flowmeter accurate to ±1.0% at a rate of 4,000mL per minute. Both ovens include a solid-state digital temperature controller with built-in over-temperature protection and 200 Watt heating element to control temperature to ±1°F at 325°F (±0.5°C at 163°C). Older MO-30 units can be upgraded with a Digital Flowmeter. Inquire for details. Specifications require test temperatures to be verified using an ASTM 13C Mercury-in-glass thermometer, available separately from Gilson as MA-223C. Electronic platinum resistance thermometers (PRT) such as MOA-12 or MOA-14 are also acceptable, offer safe and convenient operation, and avoid the regulatory restrictions of Mercury thermometers. These optional precision digital thermometers are accurate to ±0.05°C (±0.09°F), and can be specified when ordering a new oven, or ordered separately for retrofitting existing ovens. A supply of compressed air, not exceeding 125psi (8.6bar), is also required.
The RTFO features a baked enameled steel exterior, and double-wall construction for added safety and energy efficiency. The door has a large window to observe operation. The circular test rack holds eight serial-numbered RTFO Bottles (included) and rotates at 15rpm. Special stainless steel tongs with synthetic gripper pads are included for easy handling of hot bottles. Additional RTFO specimen bottles are ordered as MOA-6. Other optional accessories include the stainless steel MOA-10 Cooling Rack, designed to ASTM requirements to hold nine specimen bottles, and the MOA-5 Bottle Scraper, shaped to exactly fit RTFO bottles for removing the interior film. RTFO units are supplied without a power cord. Connection to a suitable power supply should be performed by a qualified electrician.