Brass Ford Cup

Make viscosity determinations in a room free of drafts and rapid changes in temperature. For the highest degree of precision the room temperature should be between 22 and 28°C (72 and 82°F). Determinations should be made at a temperature above the dew point of the atmosphere surround-ing the apparatus. Choose the proper cup so that the time of efflux will be between 20 and 100 s (preferably between 30 and 100 s) for cup Nos. 3, 4, and 5; between 55 and 100 s for cup No. 1; and between 40 and 100 s for cup No. 2 . Level the instrument so that a cup may be filled level full without a meniscus or overflow at one side. Determine the time in seconds of efflux as follows:Close the orifice, for example, by holding a rubber stopper against it. Fill the cup with the prepared specimen. The preferred method is to overfill the cup and scrape off the excess with a straightedge. Pull the stopper away and simultaneously start the timing device. Measure the time until the first break in the stream. Measure the temperature of the fluid in the efflux stream. If the cup has been established to be nonstandard when calibrated as described in the Appendix, apply the percent difference to the measured seconds to get the corrected viscosity in Ford-cup seconds.