[becchino]

Sorry... what does it mean?


Method 2
Procedure. Proceed as directed under Method A except that the mechanical tester provides a
fixed drop of 3 ± 0.2 mm at a nominal rate of 250 taps per minute.

Thanks

[Hunter2]

I dont know what kind of device you have, but it sounds its a kind of dosing system or similar which provides drops in a certain time and also in a certain size.
Or it is a beating (tapping) system. Which give marks with 3 mm size.

250 drops(taps) per minute with size of 3 mm

But the unit with 3 mm is strange

[mjc123]

It's not a dosing system, and it's a drop in height not a liquid drop.
It's a machine for repeatedly tapping a powder sample so that it settles to a minimum volume. (Remember those cereal packets that said "This package is sold by weight not volume. Some settling of contents may have occurred during transport"? Same principle.) This machine raises the sample by 3 mm then rapidly drops it again, repeating this 250 times per minute.

For an example of the kind of thing, see e.g. http://www.quantachrome.co.uk/en/Tap_Density_Analyzers-Autotap.asp