A depression made in the sample by a needle weight which is measured in tenths of a millimeter and expressed, as penetration number. A standard needle penetrated vertically under surcharge weight 50 gm into a sample under test temperature at 25°C for 5 second of duration. This test determine the consistency and thereby the grade of the bitumen.

• The apparatus is available in two versions, hand operated and electrically operated with automatic timer. The apparatus consist of a cast aluminum base with an iron stand on which moves an aluminum arm. A 6” dial is fixed on this arm and a brass chromium plated rod slide through the lower portion of the arm. A needle with weight is fitted to this rod. The dial is graduated from 0-400 in one tenth millimeter sub division. Supplied complete with adjustable needle holder, penetration needle, sample container, transfer dish and weight of 50 gm.
  
• The automatic model is supplied with automatic digital timer and electrical arrangement to carryout the test without need of stop watch and with great ease and accuracy.
  
• Automatic penetro meter with LVDT and auto timer can be supplied with indication of time and penetration in digital mode.