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).