GB/T 41329-2022Determination of flow rate of metallic powders - Calibrated funnel method (Gustavsson flowmeter) (English PDF)

5.1 Calibrated funnel, with the dimensions shown in Figure 1 (see Chapter 6 for the

calibration of the funnel). The dimensions of the flowmeter funnel, including the orifice, are not to be considered controlling factors. Determine the working flow rate of the funnel using reference grit as specified in Chapter 6.

The funnel shall be made of a non-magnetic, corrosion-resistant metallic material with sufficient wall thickness and hardness to withstand distortion and excessive wear.

5.2 Stand and horizontal vibration-free base, capable of supporting the funnel rigidly, e.g., as indicated in Figure 2.

5.3 Balance, of sufficient capacity, capable of weighing the test portion to an accuracy

of +/-0.05 g.

6.1 Calibration by the manufacturer of the funnel

The manufacturer shall calibrate the funnel as follows:

a) Put the reference grit (5.5) in a clean open glass bottle; dry it in the air at 110 °C for 60 min;

b) Cool the reference grit to room temperature in a desiccator;

c) Weigh 50.0 g +/- 0.1 g of the grit;

d) Operate according to the test procedures in Chapter 8;

e) Use the same 50 g of grit to repeat the above procedures, until the deviation of the five measurement results is less than 0.4 s;

f) The average value of the five measurement results shall be within the range of

40.0 s +/- 0.5 s, and marked at the bottom of the funnel.

6.2 Calibration by the user of the funnel

The flow rate of the reference grit shall be determined by the above method. If the flow rate exceeds 40.0 s/50 g +/- 0.5 s/50 g, a correction factor shall be used when measuring different powders. Use reference grit to measure the new flow rate value of the funnel.

The correction factor is obtained by dividing 40.0 by this new flow rate value.

Whether a calibration is required or not, it is recommended that the users periodically calibrate the funnel.

It is recommended that, before a correction factor is adopted, the cause of the change be investigated. If the flow rate decreases, it is probable that repeated use has burnished the orifice, and the correction factor is adjusted. An increase in flow rate may indicate a coating of soft powder on the orifice. This coating should be carefully removed and the calibration test repeated.

When the funnel is used for a period of time, if the reference grit flow time decreases to less than 37 s during calibration, it is recommended to stop using the funnel.

7.1 The mass of test sample shall be at least 200 g.

7.2 The powder shall be tested in the as-received condition. In certain cases, and after

agreement between the supplier and user, the powder may be dried. If the powder is susceptible to oxidation, the drying shall take place in a vacuum or in inert gas. If the powder contains volatile substances, it shall not be dried.

7.3 Immediately before the test, weigh out 50.0 g +/- 0.1 g of test portion.

7.4 Alternatively, weigh 90 g ~ 110 g of test portion, to a precision of +/-0.1 g or better.

Note: The intention of the alternative execution is to facilitate full automation of measurement of flow and apparent density of powders.

7.5 The determination shall be carried out on three test portions in parallel.