Humboldt H-4210A Portable, Static Cone Penetrometer - Manual (Page 3)

How To Use the Cone Index
The reading (Q
c
) is in kg/cm 2 which is essentially equal to ton/ft 2 . The cone index (Q
c
) is
read directly. The correlation between the cone index and soil constants is not absolute.
Generally, the following results have been determined through extensive field use of the
unit. Further verification of correlation in your local soil types is essential. Humboldt Mfg.
accepts no liability for the accuracy of the suggested correlations.
Standard Penetration Strength and Cohesion CBR Value (1 %)
Test “N” Value Q
u
- Unconfined compression (kg/cm 2 ) Q
c
= (2.5 to 3.3) CBR
Q
c
= 4 “N” c - Cohesion (kg/cm 2 )
Uniform clay and silty clays: Q
c
= 5 Q
u
Q
c
= 10 c
Clayey Silts: Q
c
= (10 to 20) Q
u
Q
c
= (20 to 40) c
Unpacking
As you unpack your Static Cone Penetrometer, check for the following items by referring
to the enclosed parts list and drawings:
Item 1 - Head Assembly**
Item 8 or 11 - Outer/Inner Rod Assembly
Item 18 - Cone Assembly H-4210A User Manual
Assembly and adjustment of your Penetrometer will require the above items, as well as
a 7/16" open wrench and a medium flat-blade screwdriver (not supplied). You will also
need a small wooden block or board or a hard rubber mat to check the instrument.
** The gauge installed in the Head Assembly is glycerin filled. The glycerin acts as a
shock-absorber and may have a "bubble" which is usually visible and is normal.
Assembly and Adjustment
To assemble your Penetrometer, screw the Cone Assembly (Item 18) into the Outer/Inner
Rod Assembly (Item 8 or 11) and tighten with a wrench. Next, screw this sub-assembly
into the Head Assembly (Item 1) and tighten with a wrench. Check to be sure the system
is properly adjusted by pressing the Penetrometer down onto a board or rubber mat.
The needle on the gauge should move as soon as pressure is applied . After pressure is
removed , the needle should return to zero. If the gauge does not respond when force
is applied to the Cone, turn the brass Adjustment Screw (Item 4) in the Head Assembly
(Item 1) clockwise until the needle moves. This is the zero point to the system.
If the gauge will not return to zero, turn the brass Adjustment Screw counter clockwise
until the needle returns to zero.
You should now be ready to use your Static Cone Penetrometer.