System for measuring the soil gas permeability (Type RADON-JOK)


The gas permeability of soils is one of the important factors which determine the possible Radon sources of any given site. In situ measurements of the gas permeability are therefore needed to estimate the Radon risk at specific sites.


The RADON-JOK has been developed for in situ measurements of gas permeability of soils. Its robustness and its simplicity are very practical for easy, quick and at the same time sufficiently exact in situ investigation. The principle of the RADON-JOK equipment consists of air withdrawal by means of negative pressure. Air is pumped from the soil under constant pressure through a specially designed probe with a constant surface of contact between the probe head and the soil. The constant active area is created in the head of the probe (driven into the soil to a measured depth) by the extrusion of the tip by means of the punch wire inside the probe by an exact distance. The special rubber sack, with one or two weights, pumps the air from the soil and allows for performing measurements at very low pressures. The gas permeability is calculated using the known air flow through the probe, which is defined by the known air volume (= 2000 cm3) in the rubber sack (depression of the bottom of the sack between two notches) and by the pumping time measured. The great advantage of RADON-JOK is the possibility to perform measurements independently of any source of energy.











Prof. Dr.-Ing. Hans Richard Doerfel

IDEA System GmbH, Am Burgweg 4, D-76227 Karlsruhe, Germany.