2.1 Purge the RAD7
First, purge the RAD7 with dry air in an open loop for at least 5 minutes, then switch to 1-day protocol:
select Setup, Protocol, 1-day, and push [ENTER]. Start a reading, still sampling fresh air through a
drying unit. Go to the third status window (push the [Menu] key, then push [ENTER], [ENTER], Rt
Arrow, Rt Arrow, and observe the relative humidity in the top right corner. Keep the reading going
until the RH is below 9%, then switch o
ff
the RAD7.
If a correction is to be made to the Natural Rock Sample radon reading for radon added to the air loop
by the ambient air, a
ft
er purging the RAD7, (see section 2.4), the fresh-air measurement should be kept
going until at least one and preferably two or three cycles are completed.
2.2 Hook up to the Natural Rock Sample
Hook the RAD7 up to the Natural Rock Sample in a closed loop, using the tubing and Small Drying
Tube provided with the Natural Rock Sample. Use the con
fi
guration shown in Figure 2, with the Small
Drying Tube upstream of the RAD7, and the Natural Rock Sample connection upstream of the Small
Drying Tube. If one end of the Small Drying Tube has started to turn pink, indicating that it is wet, that
end should be positioned closest to the RAD7 outlet.
2.3 Start a 3-Hour Test
Switch on the RAD7 and press the menu key. Select 1-day protocol (
Setup,
Protocol,
1-day,
[ENTER]
). Change the Recycle number to 6 (
Setup,
Protocol,
Recycle,
06,
[ENTER]
). Put the
RAD7’s infrared printer in place and switch o
ff
the RAD7.
Switch on the RAD7 printer. Switch on the RAD7 and let it print out the header, including a review of
the settings. Check the printed review to make sure the Cycle time is 00:30 (30 minutes) and the
Recycle number is 06. Open the ball valves on the Natural Rock Sample container and start a test
(
Test, Start,
[ENTER]
).
Keep the measurement going until all six cycles are complete and the summary is printed out (3 hours).
Average the last four readings. Record that average with the date. If a thoron test is to be conducted (see
Section 3), the best time to do it would be 1 - 2 hours a
ft
er the radon check (see Section 3.1.1 for
details).
2.3.1 Drying and Resealing the Natural Rock Sample
A
ft
er testing is complete, the Natural Rock Sample should be thoroughly dried and prepared for
storage. To do this, set up the Natural Rock Sample in a closed loop with a RAD7 and a laboratory
drying unit containing fresh desiccant. (At this point the Small Drying Tube that was used in the 3-
hour test should be sealed with yellow caps and set aside until the next 3-hour test is conducted.)
Th
e
Natural Rock Sample should be positioned downstream of the laboratory drying unit, and the
laboratory drying unit should be connected with the end furthest from the screw cap connected to the
Natural Rock Sample.
Th
e screw cap end, which may be pink (indicating that it is wet), should be
connected to the RAD7 outlet as shown in Figure 3, on the following page.
Sec$on 2
RAD7 Radon Sensitivity Check
5
