PTB 311E Tablet Hardness, Thickness and Length Tester


The PTB 311E/PTB 511E/PTB 811E series of 3-in-1 tablet hardness, thickness and length/diameter testers are our top-selling units and can be found in tablet press rooms across the globe. The PTB 311E series are dual force mode, digital hardness testers capable of measuring in linear force or linear speed increase modes. These instruments are made in strict compliance with the latest EP <2.9.8> and USP <1217> for Tablet Breaking Force and offer a multi-point, built-in calibration procedure. The stainless steel covers are sealed tight and make these tablet testers great for manufacturing suites. The PTB311 comes in either a 300N, 500N or 800N model for a full testing range from very soft or microtablets to tamperproof and very hard formulations.

Operating Principle

Enter the nominal values for thickness, diameter or length and hardness as well as a batch number via the PTB 311E keyboard. Select the units to measure - mm or Inch, KP (Kilopond), N (Newton) or Sc (Strong Cobb). Place the sample in to the Thickness Jaw and start the test. The drive jaw will run forward, touch and measure the tablet thickness. Then the drive jaw reverses back so that the sample falls into a horizontal position to test the tablet diameter (length) and hardness. Should an oblong tablet be tested, it is also possibe for the operator to manually turn the tablet to measure thickness then turn the tablet to measure the hardness without the use of any thickness inserts. There are different thickness test inserts available for different size tablets including

  • Thickness Test Jaw Set size 0 = 3-5mm diameter
  • Thickness Test Jaw Set size 1 = 5-8mm diameter
  • Thickness Test Jaw Set size 2 = 8-12mm diameter
  • Thickness Test Jaw Set size 3 = 12-18mm diameter
  • Thickness Test Jaw Set size 4 = 18-22mm diameter
  • Thickness Test Jaw Set size 5 = 22-26mm diameter

The PTB311 also offers oblong Tensile Test inserts to measure the break force along tablet bisects. Availble inserts include:

  • Oblong Tension Test Insert (12-16mm)
  • Oblong Tension Test Insert (16-19mm)
  • Oblong Tension Test Insert (19-24mm)
  • Oblong Tension Test Insert (up to 28mm)

Calibration and Validation

The USP requires the force sensor of a tablet hardness testing instrument to be calibrated periodically over the complete measuring range (or the range used for measuring samples) with a precision of 1N. All Pharma Test tablet hardness testing instrument can be statically calibrated over the complete measuring range by the use of
different traceable counterweights. All instruments support the checking of at least three different points during calibration to prove the linearity of the force sensor. 

The PTB 311E offers a built-in calibration program that allows 3 different certifed weights to measure the range of the load cell. The calibration report can be printed at the end of the procedure. PharmaTest offers the PTB-CAL15 and PTB-CAL30 weight sets for this purpose. It is also possible to use the PT-MT3 Magnetic Tablet to qualify the PTB311. The advantage with the PT-MT3 is it can test any the entire range as well as test reporducibility of the load cell.


  • Fully USP <1217> and EP <2.9.8> compliant
  • 300N (1-30 Kp), 500N (5-50 Kp) and 800N (8-80 Kp) load cells options 
  • Select either linear force or linear speed increase (dual mode selection)
  • Entry of time/date and up to a 12 digit batch number
  • Automatic re-start to speed up the testing sequence
  • Documentation of all results using an external Epson or HPLaser Jet Printer
  • Buil-in calibration program with multi-point calibration up to 80 kg
  • Force curve print-out
  • Data transfer via RS-232 interface
  • Hardness testing in compliance with the EP <2.9.8> and USP <1217> Pharmacopoeia
  • Test program for soft gelatine capsules
  • Test tension strength of oblongs and caplets available

***New***PT-Node Network Adapter for Printing and Data Transfer

PT-Node is an adapter that connects up to two Pharma Test instruments simultaneously to a network using a wired LAN connection. This way you can print test results from the instrument via your web browser on any local or network printer. Furthermore, it is possible to transfer the test results from the instruments to external systems in the same network. PT-Node supports PTB 311E.

PTB311 Node

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