Periodically clean the instrument with chromic acid to remove organic deposits. Dry the tube by passing a slow stream of filtered dry air through the capillary for 2 minutes. Clean the viscometer thoroughly by rinsing several times with an appropriate solvent completely. Upon completion of the test, remove the viscometer from the bath and place it in an inverted position in an oven maintained at 135 ± 5☌ until asphalt is drained off thoroughly from the viscometer. Measure to within ± 0.5 s the time required for the leading edge of the meniscus to pass between successive pairs of timing marks.
After the viscometer has remained in the bath for 30 ± 5 min open the valve and allow the asphalt to flow into the viscometer. Establish a vacuum of 30 ± 0.05 em of mercury in the vacuum system and connect it to the viscometer with the valve closed. Place the charged viscometer vertically in the waterbath with the help of a holder so that the uppermost timing mark is at least 2 embelow the surface of the bath liquid. Testing – Maintain the bath at the te st temperature within ± O.I☌.Place the charged viscometer in an oven or bath maintained at 135 ± 5.5☌ for a period of 10 ± 2 min to allow large air Charge the viscometer by pouring the prepared sample to within ± 2 mm of flll line E.Transfer about 20 ml into a suitable container and maintain it to a temperature of 135 ± 5.5☌ stirring occasionally to prevent local overheating and allow the entrapped air to escape. Preparation ofthe Sample – Heat the sample to a temperature not more than 60☌ for the tars and pitches and not more than 90☌ for bitumens above their respective approximate softening point temperature respect ively until it has become sufficiently fluid to pour.Tar viscometer, cup, valve, receiver, thermometer etc. To determine the viscosity of bitumen by tar viscometer as per IS: 1206 (Part 2)
Its defined as fluid property of the material as resistance to flow
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