Pocket Penetrometers (kPa)

[sheptech]

With the pocket penetrometers that has the dial gauge reading kg/cm² and reads from 1 - 6 on the face and using a Plunger dia of 6.35mm, is each reading on the dial in kPa. So for example 2 on the dial = 200kPa ??

Pic of PP in question attached.

 

[STVU]

Sheptech;

If the only units shown are kg/sq. cm then the values are in Kg/Sq. cm units. 2 kg/sq.cm is approximately 2 tons/sq. ft or 4,000 psf which is roughly 190 KN/sq.M So your 200 KPa is accurate.

Note, 2 doesn't mean 200 KPa, just 2 kg/sq. cm exactly or approximtely 2 TSF. So value of 6 is only 575 KPa and not 600 KPa.

 

[sheptech]

thanks STVU

that should help

 

[bmike]

Considering the precision of a Pocket Petrometer, I would consider 1 kg/ sq m sufficiently close to 100 kPa to be "close enough."

A more important error frequently encountered is to assume that the reading on the device is the undrained shear strength. It is supposed to be the unconfined compressive strength, which is twice the undrained shear strength, assuming the minor principal stress is zero (atmosphere).