An apparatus complex is developed for measurements of radon volume act
ivity by the tract method. The equipment has been attested at the D.I.
Mendeleev All-Russia Research Institute of Metrology, and is intended
for mass scale usage, the complex has passive tract radiometers of rad
on based on cellulose nitrate detectors, a spark counter of the type '
'AIST-ZV'', a thermostating etching device, as well as a calibration r
adon rack ''KARST''.