BS EN ISO 4490:2018 pdf free
BS EN ISO 4490:2018 pdf free.Metallic powders – Determination of flow rate by means of a calibrated funnel (Hall flowmeter)
The flow rate of the reference sample shall be determined by the above method. If the flow rate has changed to be outside 40,0 s±0,5 s/50 g, a correction factor shall be used when measuring different powders. This correction factor is obtained by dividing 40,0 by the value obtained above.
It is recommended that, before a correction factor is adopted, the cause of the change be investigated.
If the flow rate has decreased, it is probable that repeated use has burnished the orifice and a (new) correction factor is justified. 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.
It is recommended that the use of a funnel be discontinued after the duration of flow of the reference sample has decreased to less than 37 s.
In general, 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. However, 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.
a) Transfer the test portion to the funnel, keeping the discharge orifice properly closed, for example with a dry finger or a mechanical shutter. Take care that the stem of the funnel is filled with powder.
b) Start the timing device (5.4) when the orifice is opened and stop it at the instant when the last of the powder leaves the orifice.
c) Record the elapsed time measured to the nearest 0,1 s.
Alternatively, the orifice can be kept open when the test portion is transferred to the funnel, with the rest of the procedure being the same.BS EN ISO 4490 pdf download.
