Study on pressure correction method of radon in soil detecting instrument with pump

In the case of breathless soil, the real sample quantity of soil gas will be less than expected. Thus it results in higher error with radon concentration result. The pressure in the collecting chamber will be reduced while air expanding during pumping due to the breathless soil. According to the characteristic of air in a tight chamber, the coefficient for error correcting is derived. This method was carried out for sniff-typed radon detector calibration, so as to avoid error caused by unexpected sample quantity of soil gas. For a verifying purpose, a portable instantaneous radon in soil detecting instrument with pressure corrector was then developed. An item of Chinese Utility Model Patent was also awarded. Experiment data has been collected on two geological sections. It shows that relatively error, which caused by various sample quantity of soil gas, would be up to 60%. Therefore, good results were achieved after the pressure correcting method had been applied. (authors)