The AF650 comparator is an ergonomical 3-field instrument for visual determination of the ASTM colour of samples by direct comparison wtih coloured glass standards in accordance with ASTM D1500.
ASTM colour as specified in the standard D1500 is a single number colour scale to grade petroleum products as defined by 16 glass standards of specified luminous transmittance and chromaticity, graduated in steps of 0.5 from 0.5 to 8.0. The scale is used for a variety of petroleum products such as lubricating oils, heating oils, diesel fuel oils, mineral insulating oil and solid petroleum waxes.
The 16 glass standards are incorporated in the pair of discs which are included with the instrument.
With a 3-section field of view the sample and two adjacent standards on the ASTM Colour Scale are viewed simultaneously, making it easier to achieve the optimum colour match. For rapid colour grading within predetermined colour limits, the glass standards can be set to the two limiting colours, making it easy to see if the sample is within tolerance.
The unit features a tungsten halogen light source which is colour corrected to CIE standard illuminant C, which guarantees constant lighting conditions for colour grading, day or night and irrespective of ambient lighting.
The comparator has a fully removable sample chamber for quick and easy clean-up of spills. The disks can also be simply but securely removed, allowing replacement if required. Energy efficiency is ensured at every stage - a single press of the switch illuminates the sample for one minute, two presses for two minutes and three presses for three; this increases the lifetime of the bulb.