PDFs:
PRT Active Sampling
Field
technicians can use a PRT Expendable Point Holder to sample soil gas with
1.25-inch probe rods. This point holder accepts 1.1-inch OD Expendable
Drive Points at the lower end (Figure A). These points are
used because their 1.1-inch OD is smaller than the 1.25-inch probe rods
and therefore does not provide an annulus when driven to depth.
This size difference also means that a PRT Point Popper may be required
to push the expendable drive point out of the point holder before a vapor
sample is collected (Figure B).
A Retractable Drive Point Assembly may be used in place of the conventional expendable drive point. A PRT Retractable Point Holder is used to attach the retractable point to the tool string and also requires an AT1226 adapter. The retractable point extends upon pull-back to allow gas sampling, but remains attached to the holder for further probing (Figure C).