Overview

This instrument is designed and manufactured in accordance with the requirements specified in T0620 “Dynamic Viscosity Test of Asphalt (Vacuum Pressure Capillary Method)” of JTG 3410–2025, the Industry Standard of the People’s Republic of China for “Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering,” as well as SH/ 0557 “Method for Determining the Viscosity of Petroleum Asphalt (Vacuum Capillary Method),” the Industry Standard of the People’s Republic of China for the Petrochemical Industry.

This instrument is suitable for determining the dynamic viscosity of viscous petroleum asphalt using a vacuum reduced‑pressure capillary viscometer. Unless otherwise specified, the vacuum level shall be 300 mmHg.

This instrument is also suitable for testing other substances using the vacuum capillary method, with a test temperature of 60°C, a vacuum level of 300 mmHg (40 kPa), and a viscosity ranging from 0.0036 to 20.000 Pa·s.

Operating conditions of the instrument

1. Power Supply: AC 220V ±10%, 50Hz;

2. Ambient temperature: 0–50°C;

3. Relative humidity: ≤85%;

Technical Specifications and Key Features

(1) Technical Parameters

1. Temperature control range: 0.00–100.00°C;

2. Temperature control range: ±0.1, resolution 0.01

3. Operating pressure range: 300 ± 0.5 mmHg;

4. Timing range: 0.0–999.9 s;

5. Timing accuracy: ≤0.5%;

6. Measurement range: approximately 4.2–580,000 Pa·s;

(2) Main Features

1. It has the functions of storing and measuring time.

2. Features automatic temperature and vacuum control functions.

3. Features an automatic timing function;

4. LCD display with menu-based operation and user‑friendly prompts;

5. A high‑precision pressure sensor measures vacuum levels.

6. It can manage the parameters of three sets of capillaries simultaneously, automatically calculate the viscosity value for each segment, automatically select valid data according to regulatory requirements, and automatically compute the average based on the valid values.

7. Equipped with a printer that can print experimental results and historical data.

Main Structure and Operating Principle

This instrument consists of a temperature control system, a vacuum reduction system, a timing system, and more. It can automatically perform temperature control, vacuum reduction control, and timing functions.

Instruments and Materials

1. Vacuum-Reduced Pressure Capillary Viscometer: A Set of Three Capillaries – The three capillaries included with this instrument have been calibrated.

2 . Thermometer: 50°C–100°C, with a scale division of 0.1°C.

3 . Constant‑temperature water bath: Made of hard glass, it must be tall enough so that when the viscometer is placed inside, the highest time mark is at least 20 mm below the liquid surface. It is equipped with a heating system and an automatic temperature controller capable of maintaining the water temperature within ±0.1°C of the test temperature, as well as a stirrer and clamping device. The temperature difference between different locations within the water bath must not exceed ±0.1°C. The temperature control precision of the insulation device should ideally reach ±0.1°C.

4. Vacuum Pressure Reduction System: The vacuum level shall reach 40 kPa ± 66.5 Pa (300 mmHg ± 0.5 mmHg). A simplified schematic diagram of the entire system is shown in Figure 2; all connections must be airtight to ensure a sealed environment. When the capillary pressure reduction valve is opened for measurement, no negative pressure drop should occur. Connect a vacuum pump to the open end to evacuate the system.

5. Stopwatches: 2 units, with a resolution of 0.1 s and a total range of 15 minutes, with an error no greater than ±0.05%.

Methods and Steps

Preparatory work

1. Estimate the viscosity of the sample and select the appropriate model of vacuum capillary viscometer based on the fact that the time it takes for the sample to flow through a specified volume is more than 60 seconds.

2. Thoroughly wash the vacuum capillary viscometer with solvents such as trichloroethylene. If the viscometer is stained with oil, carefully clean it using cleaning solutions, distilled water, or other suitable agents. After washing, dry it in an oven or by blowing hot air through cotton wool.

3. Prepare the asphalt specimen according to Procedure T0602, and carefully heat the dehydrated and sieved specimen until it reaches a fully fluid state. During heating, stir appropriately to ensure uniform heating. Then pour the specimen into another small sample container that is convenient for filling into capillary tubes, using 50 ml in each case, and cover it tightly with a lid.

4. Heat the water bath and adjust the temperature to remain within a range of 60°C ± 0.1°C; the thermometer must be calibrated in advance.

5. Place the selected vacuum capillary viscometer and the sample in an oven (135°C ± 5°C) and heat for 30 minutes.

Experimental Procedure

1. Place the heated viscometer in a container, then inject the hot asphalt sample from the loading tube A into the capillary viscometer. The sample should not adhere to the tube walls, and the liquid level of the sample should be within ±2 mm of the E mark.

2. Return the capillary viscometer fitted with the sample to the electric oven (135°C ± 5.5°C) and maintain it at that temperature for 10 minutes ± 2 minutes to allow any air bubbles generated in the sample within the tube to escape.

3. Remove three capillary viscometers from the oven, cool them at room temperature for 2 minutes, then install them in a constant‑temperature water bath maintained at the test temperature. The viscometers should be positioned such that the I mark is at least 20 mm below the liquid surface of the water bath. The time taken to remove the viscometers from the oven and to complete the installation in the constant‑temperature water bath must be kept within 5 minutes.

4. Start the vacuum pump and adjust the vacuum level to 40 kPa ± 66.5 Pa (300 mmHg ± 0.5 Hg).

5. After the viscometer has been kept in the constant‑temperature water bath for 30 minutes, open the valve connecting to the reduced‑pressure system. When the sample is drawn up to the first mark, start both stopwatches simultaneously and measure the time interval between consecutive pairs of marks, accurate to 0.1 seconds. Record the symbol of the first mark that exceeds 60 seconds, along with its corresponding time interval.

6. Conduct parallel tests on the other two viscometers using this method.

7. After the test is completed, remove the capillary tube from the constant‑temperature water bath and clean it in the following sequence:

7.1 Invert the capillary tube and place it in a beaker of appropriate size, then heat it in an oven preheated to 135°C for about 0.5 to 1 hour, allowing the asphalt in the capillary tube to fully flow out. However, the heating time should not be too long, as this could cause the asphalt to char and adhere to the inside of the tube.

7.2 Remove the beaker and capillary tube from the oven, then quickly and gently wipe clean the asphalt around the mouth of the capillary tube with a clean cotton swab.

7.3 Inject trichloroethylene solvent into the sample tube, then use a rubber bulb to draw air through the upper end of the capillary tube. The asphalt will gradually dissolve and be drawn out through the capillary opening into the rubber bulb—repeat this process several times. Continue until the injected trichloroethylene is drawn out clear and transparent. Finally, rinse with distilled water, dry, and store for future use.

Calculate

The dynamic viscosity of the asphalt sample is calculated according to Formula (T0620-1).

η = K × t

In the formula: η — the dynamic viscosity of the asphalt specimen at the test temperature, in Pa·s;

K—The viscometer constant, in Pa·s/s, for the first pair of calibration lines with a time exceeding 60 seconds.

t—The time interval, in seconds, through the first pair of markers exceeding 60 seconds.

Report

The error between the parallel test results of three viscometers in a single test should not exceed 7% of the average value; otherwise, the test must be repeated. When this requirement is met, the average of the three viscometer readings shall be taken as the measured value for the asphalt dynamic viscosity meter.

Precision or Allowable Difference

The allowable difference for repeatability tests is 7% of the mean; the allowable difference for reproducibility tests is…

10%.

Usage Instructions and Precautions

1. This testing instrument should be placed horizontally on a workbench in an environment with a room temperature of 0–30°C, relative humidity no more than 80%, free from vibrations and corrosive gases, and equipped with proper grounding protection.

2. Before use, first fill the constant‑temperature water bath with pure tap water to a water level approximately 15 mm below the upper surface.

3. Plug all instruments into the power supply (220 V, 50 Hz). First, turn on the power switch for the constant‑temperature water bath, then adjust the temperature to the desired value according to the temperature controller’s user manual. After turning on the heating and stirring switches, the desired temperature will be reached after a period of time.

4. After setting up the constant‑temperature water bath, turn on the power switch for the vacuum control section. Once the power switch is turned on, the vacuum pump will start operating immediately. Users can set the desired vacuum level according to the instructions in the vacuum gauge manual (in most cases, the factory has already configured the settings for the user, so there is no need to reset them). Based on the readings on the gauge, slowly adjust the vacuum level using the pressure regulator valve—this process should be repeated several times. (At this point, the valve connected to the capillary tube must be closed.)

6. During the test, turn on the lighting switch to clearly observe the entire testing process.

Packing List

1. Asphalt Dynamic Viscometer – 1 unit

2. 1 copy of the instrument manual

3. One product certificate

4. 3 capillary tubes