GB/T 46024-2025Paints and varnishes - Determination of flow time by use of flow cups (English PDF)

1 Scope

This document describes a method for determining the flow time of paints, varnishes and related products, which can be used to monitor viscosity.

This document specifies four types of flow cups with similar dimensions but outflow orifice diameters of 3 mm, 4 mm, 5 mm, and 6 mm, and provides two methods for checking the wear of flow cups (see Appendix A).

This document does not include flow cups with replaceable outflow orifices, because the cup body with the outflow orifice does not meet tolerance requirements.

This document does not include commonly used immersion-type flow cups.

NOTE. because the manufacturing tolerances of such flow cups are greater than those specified in this document, the accuracy of obtaining flow time using the immersion-type flow cups is lower than that using the flow cups specified in this document (see Chapter 9).

The method described in this document is applicable to test materials where the breakpoint of the liquid flow from the outflow orifice of the flow cups can be accurately determined. Due to the deceleration effect, for materials with flow times close to the upper limit of the test range (100 s), the breakpoint is difficult to determine and reproduce.

2 Normative References

The contents of the following documents constitute indispensable clauses of this document through the normative references in the text. In terms of references with a specified date, only versions with a specified date are applicable to this document. In terms of references without a specified date, the latest version (including all the modifications) is applicable to this document.

ISO 1513 Paints and Varnishes - Examination and Preparation of Test Samples

NOTE. GB/T 20777-2006 Paints and Varnishes - Examination and Preparation of Samples for

Testing (ISO 1513.1992, IDT)

ISO 4618 Paints and Varnishes - Vocabulary

NOTE. GB/T 5206-2015 Paints and Varnishes - Terms and Definitions (ISO 4618.2014, IDT)

ISO 15528 Paints, Varnishes and Raw Materials for Paints and Varnishes - Sampling

NOTE. GB/T 3186-2006 Paints, Varnishes and Raw Materials for Paints and Varnishes - Sampling (ISO 15528.2000, IDT)

3 Terms and Definitions

The terms and definitions defined in ISO 4618 and the following are applicable to this document.

ISO and IEC maintain terminology databases for standardization at the following addresses.

3.1 flow time

The time elapsed from the instant the test material begins to flow from the outflow orifice of a full flow cup until the instant the material flow initially ceases near the outflow orifice.

4 Temperature Conditions

Temperature and humidity are important factors affecting test results. Deviations from specified requirements may result in incomparable results. However, the parties concerned may agree on alternative parameters and indicate them in the report.

Flow time is affected by temperature, which is very important for workability, and different types of products are affected to varying degrees.

The test temperature specified in this document is (23.0 ± 0.5) °C, which is for reference only.

Due to actual temperature conditions, comparation tests may be more convenient at other agreed temperatures (for example, 25 °C) (see Appendix B).

For viscosity monitoring via flow time, the specimen and flow cups shall be conditioned to the specified or agreed temperature, and it shall be ensured that the temperature variation during testing does not exceed 0.5 °C. The flow cups shall be placed in a non-airflow location for testing.

If the test is conducted in a fume hood with the exhaust opening open, this shall be noted in the test report.

5 Instruments