Humboldt H-4204 Proving Ring Penetrometer - Manual (Page 3)

General Information
The Proving Ring Penetrometer is a cone type of penetrometer which can be
used in a number of applications. It serves as a rapid means for determining
the penetration resistance of soils in shallow exploration work. The reading
obtained in this method maybe correlated to standard or modified
compaction data for compaction control in the field. Trafficability relationships
can be obtained for quick field evaluation of sites.
Correlation with the CBR or bearing capacity tests can be established by the
user. In conjunction with the standard laboratory and field test, the H-4204
has proven to be an extremely useful tool for quick field checks and in reducing
the possible number of the more time-consuming standard check tests.
The instrument consists of a T-handle, one 36" penetration rod, one 18"
extension rod graduated every 6", one proving ring of 220 lb. (99.79 kg)
capacity with dial indicator and a removable cone point. The cone point has
a base area of 0.983 square inch and a conical area of 1.938 square inch.
The dial indicator furnished with this assembly has a maximum reading
feature. A clutch type brake attachment maintains the reading until the brake
is manually released.
Assembly (See figure 1)
Attach the handle to the upper block of the proving ring.
Attach the penetration rod with cone attached to the lower block of the
proving ring.
If the extension rod is being used, attach it by means of the coupler
to the lower block of the proving ring and attach the penetration rod to it.
Preliminary Setting
Inspection: Inspect the instrument before use to make sure that all nuts, bolts
and joints are tight and that the dial gauge tip contacts the proving ring bearing
block screw.
Zeroing the Instrument
Allow the penetrometer to hang vertically from its handle while zeroing is
carried out. After rough adjustment to approximately zero by use of the two
lock screws on the mounting lug of the proving ring, fine adjustment maybe
accomplished by turning the hexagon head bolt (proving ring bearing
block) screwed into the half round of the lower mounting block of the ring.
With the bearing point of the dial indicator stem making contact with the
head of this screw, any movement of the screw will reflect on the ring.
A second method for zeroing the dial indicator is by adjustment of the dial face
itself. Release the knurled screw located on the upper right side of the dial
housing. After rotation of the dial face to the zero position, be certain to tighten
the knurled screw so as to maintain this position. This adjustment should be
made only for small angles since extreme non-symmetry of the dial can cause
confusion in reading.