ECOTEST DKG-21 Operating Manual page 64

Note. The distance between the mechanical center of the source and the
mechanical center of the dosimeter's detector is considered to be the
distance between the mechanical center of the source and the plane, which
is perpendicular to the direction of gamma-quanta beam spreading, and
passes through the mechanical center of the dosimeter in this plane.
5.2.7.4.4 Calculate the main relative permissible error limit of DER
measurement in percentage following the procedure according to
recommendations of DSTU GOST 8.207:2008.
5.2.7.4.5 Perform
H 
= (8±1) μSv/h in 3 minutes after the dosimeter irradiation start
( 10 )
p 0
provided that DER measurement time is 5 s, n = 5 and t = 2.78.
5.2.7.4.6 Perform
=(900±100) mSv/h.
operations 5.2.7.4.3,
operations 5.2.7.4.5
62
5.2.7.4.4 for
H 
for DER
DER
( 10 )
p 0