6. Apparatus
6.1 Mini-Rotary Viscometer - An apparatus that consists of one or more viscometric cells in a temperature controlled aluminum block. Each cell, when fitted with the specified rotor, becomes a calibrated rotor-stator set. Rotation of the rotor is achieved by an applied load acting through a string wound around the rotor shaft. The top bearing plate is fitted with locking pins for holding the rotors stationary. Time of rotation is measured electronically by a device attached to the timing wheel.
6.1.1 The mini-rotary viscometric cell for this procedure has the following typical dimensions:
6.2 Weight - For applying mass. Weights are to be in increments of 2.5 g +/- 1 %. A minimum of eight weight segments will be needed for the measurements defined in this test method. One segment will be the weight holder.
6.3 Temperature Control System - That will regulate the samples in the cells according to the cooling program described in Table X1.1 and within the tolerances specified in the table.
6.4 Temperature Measuring Device - Use either a DCT meeting the requirements described in 6.4.1 or liquid-in-glass thermometers described in 6.4.2. A calibrated DCT or calibrated low temperature liquid-in-glass thermometer shall be used as the thermometer for temperature measurement below 25 °C independent of the instrument's temperature control, and shall be located in the thermowell.
NOTE 1 - The DCT display device and sensor must be correctly paired. Incorrect pairing will result in temperature measurement errors and possibly irreversible damage to the electronics of the display.
6.4.1 Digital Contact Thermometer Requirements:
NOTE 2 - With respect to DCT probe immersion depth, a procedure to determine minimum depth can be found in Guide E2877, Section 5.3, or Test Methods E644, Section 7.
6.4.1.1 The DCT calibration drift shall be checked at least annually by either measuring the ice point or against a reference thermometer in a constant temperature bath at the prescribed immersion depth to ensure compliance with 6.4.1. With respect to an ice bath, Practice E563 provides guidance on the preparation and use ofan ice bath. However, for this use, variance from the specific steps, such as water source, is permitted provided preparation is consistent. The basis for the variance is due to the ice bath reference being used for tracking change in calibration not verification.
NOTE 3 - When a DCT's calibration drifts in one direction over several calibration checks, that is, ice point, it may be an indication of deterioration of the DCT.
6.4.2 For liquid-in-glass thermometers, LiG, two are required. One LiG shall be a calibrated 76 mm partial immersion thermometer with a scale from +5 °C to 1 degree lower than the lowest test temperature in 0.2 °C subdivisions. For test temperatures less than -35 °C, use a liquid-in-glass thermometer with at least a scale range of 2 degrees Celsius in 0.2 °C subdivisions. The low temperature LiG thermometer(s) shall have a report of calibration showing the temperature deviation at each calibrated test temperature. The second LiG thermometer shall be a 76 mm partial immersion thermometer graduated from at least +40 °C to 90 °C in 1 °C subdivisions, which is used to verify the preheat temperature.
6.4.2.1 Calibration Check - Verify the low temperature thermometer at least annually against a reference thermometer in a constant temperature bath or in an ice bath. The thermometer is to be insert to its immersion depth. If using an ice bath, the ice point reading is to be taken within 60 min after the thermometer has been at test temperature for at least 3 min. If the corrected temperature reading deviates from the reference thermometer or the ice point then repeat this calibration check. If the thermometer deviates from the reference value on two successive checks then a full thermometer recalibration is needed.
6.4.2.2 Recalibration - A complete recalibration of the liquid-in-glass thermometer, while permitted, is not necessary in order to meet the accuracy ascribed to liquid-in-glass thermometer's design until the thermometers corrected measured temperature deviates from the reference thermometer or ice point by one scale division, or until five years has elapsed since the last full calibration.
6.5 Supply of Dry Gas - A supply of dry filtered gas to minimize moisture condensation on the upper portions of the instrument.
6.5.1 For thermoelectric cooled instruments, which use cell caps, the dry gas supply is connected to the housing cover. The supply of dry gas is discontinued when the cover is removed for the measurement phase of the test.
6.6 Locking Pin - A device to keep the rotor from turning prematurely and able to stop the rotor at the nearest half revolution by interaction with the rotor crossbar.
7. Reagents and Materials
7.1 Low Cloud-point, Newtonian Oil, a calibration oil of approximately 60 Pa·s viscosity at -25 °C for calibration of the viscometric cells. The calibration oil shall be obtained from suppliers complying with ISO Guide 34 and ISO 17025 with traceability to a national metrology institute (NMI).
7.2 Oil Solvent, commercial heptanes or similar solvent for the test fluids that evaporates without leaving a residue. (Warning - Flammable.)
7.3 Acetone - A technical grade of acetone is suitable provided it does not leave a residue upon evaporation. (Warning - Flammable.)