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Quantachrome Leaders in Characterizing Porous Materials & Powders

Autotap- Tapped Density Analyzer

Tap density of powders, granules, flakes and other finely divided solids is an important characteristic and commonly measured property of numerous materials.  The Autotap automates the lifting and dropping of the powder container (usually a glass graduated measuring cylinder) thereby eliminating both the expected variability and possible wrist injury when done by hand, not least because most materials require hundreds if not thousands of taps before reaching maximum tapped density. If you need to ensure the same fixed number of taps for all analyses, a special lockout feature is provided which prevents unauthorized changes to the counter.

Available Options
The Autotaps are normally supplied with 250ml cylinders, but you may request 10ml, 25ml, 50ml, 100ml or 50ml instead.  A larger optional platform is required to accommodate the largest cylinder we offer, the 1000ml.  But, of course, this platform does accommodate all the smaller cylinders too.


Tap (Tapped) Density

Dual Autotap Both Autotaps conform to a number of international standards for tap density, namely ASTM B527, D4164 and D4781, plus British Pharmacopoeia method for Apparent Volume, USP <616> method II, and ISO 787-11. The unique platforms accommodate different size cylinders for different standards and for differing amounts of available sample. Most samples are analyzed "as-is", normally there is no special preparation needed, just pour the powder into a suitably sized cylinder. Securing (and releasing) the cylinder(s) on the platform(s) is both easy and rapid. Then just dial in the desired number of taps and press "start". Tapping ceases automatically after the prescribed number of taps.

Hausner Ratio & Carr's Compressibility Index

By comparing the initial (loose) powder volume with the final (tapped) volume one can predict the flowability of a powder.  This comparison is normally done by calculating the ratio of the volumes (Hausner) or the change in volume as a percentage of the initial volume (Carr’s).  For more details, please request our technote  No.30 " Tapped Density in the Pharmaceutical Industry" here

Geometric (envelope) density

Sometimes called particle density or apparent density, the geometric density reflects the volume of particles including internal pores and small surface irregularities.  Important, therefore, for a host of manufactured and natural porous materials it is simply and inexpensively measured using a dry powder pycnometer attachment for the Autotap and either a coarse or fine pycnometric powder, according to the scale of pore size and surface features under test.  For more details, please request our technote No.24 " Geometric (Envelope) Density without Mercury (Tap Density)" here

Feature Article: "The Role of Porosity"

...bulk volume can be determined by Dry Powder Pycnometry. This technique entails measuring the increase in volume of a packed bed of powder when the sample is immersed in it, Archimedes style". more...


  • Available as 110-220V/60Hz or 220-240V/50Hz
  • Tap height: 3mm(1/8").
    Optional 1mm drop also available.
  • Tapping rate: 260 per minute
  • Tap counter: 1- 999999 with auto-stop
  • Continuous tapping: yes, if so desired (manual stop)
  • Platform rotation: automatic
  • Controls: on/off, start, stop, counter reset.
  • Load limit: 900g (2lb) with no effect on tapping rate.

Laboratory Services

Lab QMCTap density, Hausner Ratio, Carr's Index and Geometric Density are just a few of the measurements offered by our Applications Laboratory on a fee basis. Click here for more details including sample submission instructions.

Those seriously considering the purchase of an instrument may request free evaluation analyses (no more than two please) or a demonstration in their facility.  Please make your requests using this form

A Note on Standard Methods

Because of copyright restrictions, Quantachrome cannot provide copies of standards published by other organizations such as ASTM International.  However they are available for purchase online, together with those of ISO and DIN, at