DURRIDGE RAD7 User manual

RAD7 RADON DETECTOR
User Manual
Owner__________________________
Serial #______________
SERVICE RECORD
Date Service
It is recommended that the unit be returned to DURRIDGE Co annually, for recalibration.
DURRIDGE COMPANY Inc.
7 Railroad Avenue, Suite D
Bedford, MA 01730
Tel: [phone]
[email protected]
© 2009 DURRIDGE Co. www.durridge.com

WARNING
The mains plug for this instrument shall only be inserted in a socket outlet
provided with a protective ground contact. Any interruption of the protective
conductor may make the instrument dangerous.
Opening the cover of this instrument is likely to expose dangerous voltages.
Disconnect the instrument from all voltage sources while it is being opened.
Due to battery power, the instrument may still be dangerous.
Using this instrument in a manner not specified by the manufacturer may impair the protection provided
by the instrument.
2

TABLE OF CONTENTS
....................................................................................................INTRODUCTION 9
...........................................................................1. GETTING STARTED: 10
YOUR FIRST DAY WITH THE RAD7 10
..............................................................................................1.1 Unpacking 10
....................................................................1.2 General Safety Instructions 10
........................................................................................1.3 Taking a Look 11
..........................................................................1.4 Starting a Two-day Test 12
................................................................................1.5 Starting a Sniff Test 14
.........................................................2. BASICS OF RAD7 OPERATION 16
............................................................................................2.1 Introduction 16
.......................................................................................................................2.1.1 The Key Pad 16
....................................................................................................................2.1.2 Command List 16
.........................................................................................................2.2 Test 16
...........................................................................................................................2.2.1 Test Status 16
......................................................................................................2.2.1a Quick Save-and-Restart 17
......................................................................................................2.2.2 Test Start and Test Stop 18
.............................................................................................................................2.2.3 Test Save 18
............................................................................................................................2.2.4 Test Clear 18
...........................................................................................................................2.2.5 Test Purge 18
.............................................................................................................................2.2.6 Test Lock 19
............................................................................................................................2.2.7 Test Sleep 19
............................................................................................................................2.2.8 Test Print 19
.............................................................................................................................2.2.9 Test Com 19
........................................................................................................2.3 Data 19
...........................................................................................................................2.3.1 Data Read 19
...........................................................................................................................2.3.2 Data Print 20
............................................................................................................................2.3.3 Data Com 20
....................................................................................................................2.3.4 Data Summary 21
............................................................................................................................2.3.5 Data Free 21
.........................................................................................................................2.3.6 Data Delete 21
..................................................................................................................2.3.7 Data Renumber 21
..........................................................................................................................2.3.8 Data Erase 22
......................................................................................................2.4 Setup 22
....................................................................................................................2.4.1 Setup Protocol 22

Table 2.4.1 Preset protocols 22
.........................................................................................................................2.4.2 Setup Cycle 22
......................................................................................................................2.4.3 Setup Recycle 22
.........................................................................................................................2.4.4 Setup Mode 23
......................................................................................................................2.4.5 Setup Thoron 23
.........................................................................................................................2.4.6 Setup Pump 24
...........................................................................................................................2.4.7 Setup Tone 24
......................................................................................................................2.4.8 Setup Format 24
..........................................................................................................................2.4.9 Setup Units 24
......................................................................................................................2.4.10 Setup Savuser 25
.........................................................................................................................2.4.11 Setup Clock 25
......................................................................................................................2.4.12 Setup Review 25
....................................................................................................2.5 Special 25
.......................................................................................................................2.5.1 Special Ident 26
....................................................................................................................2.5.2 Special SPrOn 26
....................................................................................................................2.5.3 Special SPrOff 26
..................................................................................................................2.5.4 Special SetBaud 26
......................................................................................................................2.5.5 Special Status 26
.......................................................................................................................2.5.6 Special Start 26
........................................................................................................................2.5.7 Special Stop 26
.................................................................................................................2.5.8 Special Comspec 26
...................................................................................................................2.5.9 Special ComAll 26
....................................................................................................................2.5.10 Special SPrAll 26
....................................................................................................................2.5.11 Special S-Load 26
...................................................................................................................2.5.12 Special Version 26
.....................................................................................................................2.5.13 Special Model 26
......................................................................................................................2.5.14 Special Serial 26
.......................................................................................................................2.5.15 Special Beep 27
....................................................................................................................2.5.16 Special Relays 27
.......................................................................................2.6 Infrared Printer 27
Alpha Energy Spectrum 28
..................................................3. BASICS OF RAD7 TECHNOLOGY: 29
HOW IT WORKS 29
............................................................................................3.1 Introduction 29
...............................................................................3.2 Radon Decay Chain 29
Radon and Thoron decay chains 30
............................................................................................................3.2.1 Radon-222 (Radon) 31
...........................................................................................................3.2.2 Radon-220 (Thoron) 31
.............................................................................3.3 Continuous Monitors 31
...................................................................................................3.4 Sniffers 32
........................................................................................3.5 Working Level 32
....................................................................3.6 RAD7 Solid-State Detector 33
4

.....................................................................................3.7 RAD7 Spectrum 33
................................................................................................3.8 Windows 34
................................................................................3.9 Isotope Equilibrium 35
..........................................................................3.10 Modes: Sniff and Auto 36
............................................................................................3.11 Background 36
........................................................................3.11.1 Short-lived Radon and Thoron Daughters. 36
.........................................................................................................3.11.2 Adsorbed Radon Gas. 37
............................................................................................3.11.4 Long-lived Radon Daughters. 37
...................................................3.11.5 Contamination by Radon, or Thoron, Producing Solids. 37
........................................................................................................3.11.6 Other Alpha Emitters. 37
................................................................................................3.11.7 Beta and Gamma Emitters. 37
............................................................................3.12 Precision & Accuracy 37
...............................................................................3.13 Spectrum Examples 39
................................................................................................3.13.1 Operational Radon Spectra 39
...................................................................................................................3.13.2 Thoron Spectra 40
..........................................................................................................3.13.3 Combination Spectra 41
..........................................................................................................3.13.4 Pathological Spectra 43
...............................................................................4. USING THE RAD7: 45
GOOD OPERATING PROCEDURES 45
............................................................................................4.1 Introduction 45
..........................................................................4.2 Continuous Monitoring 45
........................................................................................................................4.2.1 Preparation 45
...............................................................................................................................4.2.2 Purging 45
......................................................................................................................4.2.3 Test Location 45
.......................................................................................................................4.2.4 Test Protocol 46
....................................................................................................4.2.5 To Print Or Not To Print 46
..............................................................................................4.2.7 Security and Quality Control 47
...............................................................................................................4.2.8 Finishing the Run 47
............................................................................................................4.2.9 Examining the Data 48
...............................................................................................4.2.10 Very Short Term Monitoring 48
..................................................................................................4.3 Sniffing 48
..........................................................................................................................4.3.1 Why Sniff? 48
.............................................................................................4.3.2 Locating Radon Entry Points 48
........................................................................................................................4.3.3 Preparation 49
...............................................................................................................................4.3.4 Purging 49
.................................................................................................................4.3.5 Running the Test 49
.....................................................................................................4.3.6 Drilled Sampling Points 50
.....................................................................................................................4.3.7 Spot Readings 50
.......................................................................................4.4 Grab Sampling 50
........................................................................................................................4.4.1 Applicability 50

........................................................................................................................4.4.2 Preparation 50
..............................................................................................................................4.4.3 Protocol 51
...............................................................................................................4.4.4 Taking the Sample 51
..............................................................................................................................4.4.5 Analysis 51
......................................................................................4.5 Radon in Water 51
............................................................................................................................4.5.1 RAD H2O 51
.........................................................................................................................4.5.2 RAD AQUA 51
..................................................................................4.6 Soil Gas Sampling 51
..........................................................................................................................4.6.1 Application 51
....................................................................................................................4.6.2 Soil Gas Probe 52
........................................................................................................................4.6.3 Preparation 52
.................................................................................................................4.6.4 Running the Test 52
..........................................................................................................4.6.5 Interpreting the Data 52
........................................................................4.7 Emission Measurements 52
..........................................................................................................................4.7.1 Application 52
................................................................................4.7.2 Open or Closed Loop Configurations 52
....................................................................................................................4.7.3 Bulk Emissions 53
................................................................................................................4.7.4 Surface Emission 53
.............................................................................4.8 Thoron Measurement 53
..............................................................................................................4.8.1 Thoron and Radon 53
...............................................................................................4.8.2 Thoron Measurement Issues 54
...........................................................................4.8.3 Calculation and Interference Correction 54
.............................................................................4.8.4 Avoiding Longer Lived Decay Products 54
....................................................4.8.5 Decay Correction, Flow Rate, and Thoron Calibration 55
.................................................................................................4.8.6 Calculating Sample Decay 55
............................................................................4.8.7 Calculating Internal Cell Concentration 55
......................................................................4.8.8 Internal Cell Thoron Sensitivity Calibration 55
......................................................................................4.8.9 Setting up a Thoron Measurement 56
......................................................................................................................4.8.10 Thoron Mode 56
...........................................................................4.9 Managing Background 56
........................................................................................5. PC Connection 57
.................................................................................5.1 RS-232 Serial Port 57
........................................................................................................................5.1.1 Capabilities 57
................................................................................................................5.1.2 Hardware Bridge 57
..................................................................................................................5.1.3 Software Bridge 57
........................................................................................................................5.1.4 Applications 57
...............................................................................5.1.5 Technical Specifications for the RAD7 57
..............................................................................................................5.1.6 Serial Port Output 58
..............................................................................................5.2 RADLINK 58
........................................................................................................................5.2.1 Capabilities 58
......................................................................................................................5.2.2 Requirements 59
.......................................................................................5.2.3 RAD7 Remote Command Format 59
........................................................................................................................5.2.4 Special Keys 60
6

.............................................................................................................5.2.5 Special Commands 60
...............................................................................................6. CAPTURE 61
............................................................................................6.1 Introduction 61
..............................................................................................6.2 Installation 61
.........................................................................................6.3 File from disk 61
......................................................................6.4 Downloading from RAD7 62
..............................................................................................................................6.4.1 Connection to RAD7 62
6.4.2 RAD7 Setup 62
....................................................................................................................................6.4.3 CAPTURE Setup 62
................................................................................................................................6.4.4 Initiating download 62
....................................................................................................6.5 Parsing 63
.................................................................................6.6 Thoron Parameters 63
6.6.1 Spill factor 63
...................................................................................................................................6.6.2 Thoron sensitivity 63
............................................................................................6.7 Main Graph 64
6.7.1 Time axis 64
............................................................................................................................................6.7.2 Vertical axis 64
6.7.3 Graph lines 65
6.7.4 Data points 65
............................................................................................................................................6.7.5 Cursor lines 65
6.7.6 Mouse 66
...............................................................................6.8 Graph Control Panel 66
6.8.1 Smoothing 66
6.8.2 Line weight 66
6.8.3 Units 66
...........................................................................................................................................6.8.4 Graph Zoom 66
................................................................................................................................6.8.5 Show radon, thoron 66
............................................................................................................................................6.8.6 Lock Y scale 66
..........................................................................................................................................6.8.7 Show Legend 66
............................................................................................................................................6.8.9 Show Points 66
6.8.10 Show log 67
......................................................................................................................................6.8.11 Show Spectrum 67
6.8.12 Show Stats 67
................................................................................................6.9 Spectrum 67
.................................................................................................................................6.9.1 Spectrum synthesis 67
.....................................................................................................6.9.2 Pathological spectra and CAPTURE 67
.................................................................................................................................6.9.3 Bar chart spectrum 67
...............................................................................6.10 Graph Statistics box 67
..................................................................................................................................6.10.1 Entire data range 67
........................................................................................................................................6.10.2 Selected data 67
.........................................................................................................................6.10.3 Point nearest to cursor 67

......................................................................................6.11 Drop Down Menus 68
...........................................................................................................................................6.11.1 Preferences 68
..........................................................................................................................................6.11.2 Export Data 68
............................................................................................................................6.11.3 Export Selected Data 68
...............................................................................................................................6.11.4 Save Graph Picture 68
6.11.5 Join Data 68
..............................................................................................................................6.11.6 Copy Graph Picture 68
6.11.7 View menu 68
.......................................................................................................7. Maintenance 69
................................................................7.1 Accessories - Usage and Care 69
............................................................................................................................7.1.1 Desiccant 69
.......................................................................................................7.1.2 Laboratory drying unit 69
............................................................................................7.1.3 Small drying tube (small tube) 69
......................................................................................................7.1.4 Cascading drying tubes 70
.................................................................................................................................7.1.5 Filters 70
..............................................................................................................................7.1.6 Batteries 70
........................................................................7.1.7 Real-time Clock and Non-volatile Memory 71
............................................................................................................7.1.8 Printer and Adapter 71
....................................................................................7.2 Operating ranges 71
.................................................................................7.3 Service and Repair 72
.........................................................................................................................7.3.1 Calibration 72
.................................................................................................................................7.3.2 Repair 72
..............................................................................................................................7.3.3 Shipping 72
............................................................................................................................7.3.4 Upgrades 72
.......................................................................7.4 RAD7 Quality Assurance 73
.............................................................................................................................7.4.1 Spectrum 73
.........................................................................................................................7.4.2 Spill Factor 73
.............................................................................7.5 RAD7 Specifications 73
DURRIDGE COMPANY Inc.
7 Railroad Avenue, Suite D
Bedford, MA 01730
Tel: [phone]
Fax: [phone]
email: [email protected]
web: WWW.DURRIDGE.COM
8

INTRODUCTION
The RAD7 is a highly versatile instrument that can form the basis of a comprehensive radon measurement
system. It may be used in many different modes for different purposes. This manual adopts a progressive
approach, in which there is, first, a simple, step-by-step description of how to get readings for a) real-time
monitoring, and b) sniffing. Next comes a more detailed description of the many features of the
instrument and how to access them. The rest of the manual covers a whole range of topics, in somewhat
arbitrary order. We recommend that, as soon as possible, you read the entire text, just so that you will
have an idea of what there is. While you can start to make good measurements on the first day of
ownership of the RAD7, it can take years to master the subtleties of radon and thoron behaviour, and to
appreciate the full capabilities of the instrument.
We have tried to make the manual easy to use, with a useful table of contents. Please let us know how
well we have succeeded. If there are some topics inadequately covered, please tell us. We will issue
updates from time to time.
Points of special note
The RAD7 is a rugged and long-lasting piece of equipment. There are many units still in daily use that
were sold nine years ago or more. However, it is a sophisticated, precision electronic device, and it is not
hermetically sealed, so please treat it with respect. Please do not allow water, other liquids or dirt to get
into the machine. If using it somewhere where it may get splashed, damaged, or exposed to rain, please
protect it.
The batteries are lead-acid technology, like a car’s. If left in a discharged state they will, like a car’s, lose
capacity. After running the RAD7 on its batteries please recharge them as soon as possible (by plugging
in the unit and turning it on). With careful use, the batteries, like a car’s will last five years or more.
Finally, there is one security feature that is sometimes inadvertently set by an inexperienced, though
authorized, user; namely the key pad lockout. If the key pad ceases to function, and all you see is
“DURRIDGE RAD7" on the display, just do the following: Hold down the ENTER and two arrow keys
until you hear a beep, release the three keys and immediately push MENU. You should then be rewarded
by “Test” on the display. If the tone was set to OFF, then you will not hear the beep, so hold the three
keys down for three to four seconds, before releasing them and pushing MENU, - try hold-down times a
little longer, or shorter, if, at first, you do not succeed.

1. GETTING STARTED:
YOUR FIRST DAY WITH THE RAD7
1.1 Unpacking
First make sure you have everything you’re
supposed to have. Take the materials out of the
packing boxes and see if you have all the items
shown below or on the packing list enclosed with
the shipment. If anything is missing, please call
DURRIDGE immediately at [phone].
RAD7 monitor
Power cords
Shoulder strap & keys
Printer
2 sets Velcro tabs
3 rolls printer paper
Printer adapter
6 inlet filters
1 dust filter
Vinyl tubing: 3 pieces 3' long
Large drying tube
4 small drying tubes
5 lbs. desiccant (drying granules)
CAPTURE CD
Null-modem computer cable
USB adapter
Manual
1.2 General Safety Instructions
For your own safety and the proper operation of
RAD7:
DO NOT spill liquids onto the machine.
DO NOT expose operating panel of machine to
rain or any other excess moisture.
DO NOT allow liquid to be sucked into inlet tube.
If you intend to use the instrument in a harsh
environment, give it some protection. Even just a
transparent plastic bag enclosing the RAD7 (but
not the air sampling tube) can protect it from
splashing mud and water. Allowing the dry air
from the RAD7 outlet to exhaust into the interior
of the bag will keep the RAD7 in a clean and dry
environment.
If liquid does get into the machine, please
disconnect the power cord, turn off the power
switch, and return the RAD7 to DURRIDGE for
repair.
Do not use your RAD7 if the instrument is
damaged or malfunctioning. Please call, or email,
the DURRIDGE service department, who will
advise what to do about the problem.
Replace a frayed or damaged power cord
immediately.
Electrical equipment may be hazardous if
misused. Keep away from children.
Do not open or attempt to repair the machine.
The detector has an internal high voltage supply
that can generate more than 2,500 volts.
Warning: This machine is intended to be
electrically grounded when externally powered.
The power cord is equipped with a plug, to fit
only into a grounding-type AC outlet.
The instrument is factory set to either 120 VAC or
240 VAC operation. The setting is indicated on
the input power label.
The batteries are Gates Monobloc type
0819-0012, 6V 2.5Ah. There are two installed in
the instrument. They are not user replaceable.
Chapter 1
10

1.3 Taking a Look
The RAD7 Professional Electronic Radon Detector
Power Socket
Printer
RS-232 Serial Port
Air Outlet
Air Inlet Filter
On-Off Switch
Infra-red
LED
Menu Key
Enter Key
LCD Left Arrow Key
Right Arrow Key
Chapter 1
11

1.4 Starting a Two-day Test
You will need the RAD7 and power cord, the
Laboratory Drying Unit (the large tube of
desiccant, with a screw cap at one end), an inlet
filter (one of the six small filters supplied), the
piece of tubing with a 5/16” ID segment at one
end and a ⅛” ID segment at the other and the
printer.
On first starting up, you will need to set the clock
for your time zone (See Setup Clock, page 26).
Switch on the RAD7, push [MENU], then push
[➔] twice. You will see Setup on the display.
Push [ENTER], then push [➔] ten times. You
will see Setup Clock. Push [ENTER]. Use arrow
keys to adjust hours, minutes, seconds, day,
month and year, pushing [ENTER] to confirm
each setting. Now we are ready to continue.
a) Attach the filter to the tubing (push it into the
end with the insert).
b) Carefully remove both plastic caps from the
Drying Unit (you will need them later, to reseal
the unit). Attach the sleeved end of the tubing to
the tube fitting, on the Drying Unit, farthest from
the screw cap.
c) Attache the filter to the Inlet port of the
RAD7. The air sampling system is now set up for
the measurement.
d) Plug in the RAD7 and switch on.
e) Push [MENU], [ENTER], then push [➔] four
times. You should see on the LCD display: Test
Purge.
f) Push [ENTER]. The pump should start.
g) Set up the printer (insert paper and batteries -
see manual).
h) Place printer between green lines on face
plate (See photo, page 10).
I) After purging for some time (normally, at
least five minutes), push [MENU], and [➔] two
times, you will see: Setup on the display.
j) Push [ENTER] twice, then push either arrow
key repeatedly until you see:
Protocol: 2-Day on the display. Push [ENTER].
k) With Setup on the display, push [ENTER],
then [➔] seven times, to see Setup Format on the
display. Push [ENTER] then use arrow keys to
select Format: Short. Push [ENTER].
l) Switch off the RAD7. Switch on the printer,
now switch the RAD7 back on. The printer will
print out something like the following:
DURRIDGE RAD7
Vers 2.5f 991128
Model 711
Serial 00512
Calib 21-MAY-08
Last used
FRI 21-MAY-08 17:30
Current settings
FRI 21-MAY-08 19:09
Protocol: 2-Day
Cycle: 01:00
Recycle: 48
Mode: Auto
Thoron: Off
Pump: Auto
Tone: Geiger
Format: Short
Units: pCi/L C
m) Push [MENU], [ENTER], [➔]. You should
see on the LCD display: Test Start
n) Push [ENTER]. The pump will start running.
On the LCD display you will see something like:
0101 Live Sniff
00:59:37 00001
You are now monitoring the radon level right
where you are. Every hour, the printer will print
out a reading something like this:
0102 2.69 " 0.73 p Sniff
FRI 21-MAY-08 19:41
26.8 C RH: 7% B:7.06V
Where 0102 are the run (01) and cycle (02)
numbers, 2.69 is the measured radon
concentration, 0.73 is the STATISTICAL
uncertainty (see page 41), p indicates the units (in
this case pCi/L), and Sniff shows that, for this
reading, only the Po-218 decays (see page 33) are
being counted (after three hours, the mode
changes automatically to Normal). The second
line is clearly the date and time, while the third
shows the temperature and humidity inside the
measurement chamber, and the battery voltage.
Medium and Long format settings print more
information each cycle.
If you allow the RAD7 to complete a run, it will
print out a summary of the entire run, including:
Chapter 1
12

1. Date and time
2. Machine serial number
3. Average value for the test
4. Bar chart of the individual readings, and
5. Cumulative alpha energy spectrum.
In the example shown it may be seen that the
average level was 3.71 pCi/L, or 137 Bq/m3.
To terminate the run early, you may switch off the
RAD7. The data collected, to the end of the last
completed cycle, is automatically stored in the
RAD7 memory, and available for later display,
printing or download to a PC. If you wish to store
the last, incomplete cycle data as well, use Test
Save before switching off the RAD7. When you
do this, the end-of-run printout does not take
place. The summary is stored in memory and
may be printed at any time, except that the
cumulative spectrum, which would have been
printed out at the end of the run, is lost.
End-of-Run Printout
Chapter 1
13

1.5 Starting a Sniff Test
Sniffing lets you make quick, qualitative surveys
of radon and thoron levels. It may be used to
search for radon entry points. There are some
advantages in sniffing for both thoron (see page
33) and radon at the same time (see page 53), so
that is the procedure described here.
You will need the same equipment as for the 2-
day test, above, except that a small drying tube
should be used, instead of the laboratory drying
unit. Also, for portability, you may remove the
external power from the RAD7, and run both the
RAD7 and the printer on their batteries.
If you have not already done so, set the clock, as
described above.
a) Attach the filter to the tubing (push it into
the end with the ⅛” ID segment).
b) Carefully remove both plastic caps from
the small drying tube (you will need them later, to
reseal the unit). Attach the 5/16” ID end of the
tubing to one end of the tube.
c) Attache the filter to the Inlet port of the
RAD7. Make sure it is firmly fit onto the inlet.
The air sampling system is now set up for the
measurement. While testing, you can use the
small drying tube as a wand, to collect your air
sample from the location of interest.
d) Plug in the RAD7 and switch on.
e) Push [MENU], [ENTER], then push [➔]
four times. You should see on the LCD display:
Test Purge.
f) Push [ENTER]. The pump should start.
g) Set up the printer.
h) Place printer between green lines on the
face plate (See photo, page 10).
I) After purging for a few minutes push
[MENU], and [➔] two times, you will see: Setup
on the display.
j) Push [ENTER] twice, then push either
arrow key repeatedly until you see:
Protocol: Thoron on the display. Push [ENTER].
(See page 24 for difference between Thoron and
Sniff protocols).
k) With Setup on the display, push
[ENTER], then [➔] seven times, to see Setup
Format on the display. Push [ENTER] then use
arrow keys to select Format: Short. Push
[ENTER].
l) Switch off the RAD7. Switch on the
printer, now switch the RAD7 back on. The
printer will print out something like the following:
DURRIDGE RAD7
Vers 2.5f 991128
Model 711
Serial 00512
Calib 21-MAY-08
Last used
WED 23-MAY-08 17:30
Current settings
FRI 25-MAY-08 19:09
Protocol: Thoron
Cycle: 00:05
Recycle: 00
Mode: Sniff
Thoron: On
Pump: Auto
Tone: Geiger
Format: Short
Units: pCi/L C
m) Push [MENU], [ENTER], [➔]. You
should see on the LCD display: Test Start
n) Push [ENTER]. The pump will start
running. On the LCD display you will see
something like:
0201 Live Sniff
00:04:37 00001
You are now sniffing for thoron and radon. Every
five minutes, the printer will print out a reading
something like this:
0203 2.69 " 2.83 p Sniff
1.68 " 2.15 p Thoron
FRI 21-MAY-99 19:41
26.8 EC RH: 7% B:7.06V
Where 0203 are the run (02) and cycle (03)
numbers, 2.69 is the measured radon
concentration, 2.83 is the STATISTICAL
uncertainty (see page 41), p indicates the units (in
this case pCi/L), and Sniff shows that, for this
reading, only the Po-218 decays (see page 33) are
being counted. The second line is the measured
thoron concentration and uncertainty. The third
line is now the date and time, while the fourth
shows the temperature and humidity inside the
Chapter 1
14

measurement chamber, and the battery voltage.
Medium and Long format settings print more
information each cycle.
Note that the Po-218 has a 3-minute half life.
After moving to a new location, it will take about
15 minutes for the count rate to reach equilibrium
with the new radon concentration. So not until
after the third 5-minute cycle will the reading
indicate the new level. However, the thoron
daughter, Po-216, has a very short half life (150
ms), so the response of the RAD7 to thoron is
virtually instantaneous. For thoron, the first 5-
minute cycle is as good as any other.
Thoron will only be found very close to radon
entry points. That, together with its fast response,
makes thoron sniffing an excellent sleuth for
radon entry points.
To terminate the run any time, you may switch off
the RAD7. The data collected, of completed
cycles, is stored in the RAD7 memory, and
available for later display, printing or
downloading to a PC.
Chapter 1
15

2. BASICS OF RAD7 OPERATION
2.1 Introduction
2.1.1 The Key Pad
The RAD7 is operated through a four-key menu-
driven interface. These four keys allow you to
look at the commands, select one, and then do it.
Menu Key
Press [MENU] and you see the menu prompt (>)
and the word Test:
>Test
Arrow Keys
Press the forward and backward arrow keys to go
through the available options. To advance quickly
through the options, hold down the key so that it
"auto-repeats."
The arrow keys allow you to move right and left
through the various commands, looking for the
action you want.
Enter Key
When you have decided on a certain menu option,
you select it by pressing [ENTER]. The enter key
tells the RAD7 that you have made your selection.
You are telling it what you want it to do.
The enter key makes it happen.
2.1.2 Command List
The RAD7 command list has four command
groups: Test, Data, Setup and Special. The Test
group of commands controls the collection of new
radon data. The Data group retrieves data from
memory, outputs them, and gets rid of old,
unwanted data. The Setup group prepares the
RAD7 to operate according to your requirements.
The Special group is a set of commands that are
available when RADLINK, the remote control
software, is loaded.
2.2 Test
The Test group of commands controls the
collection of radon data and allows you to
manipulate the current test (test-in-progress). You
can start and stop data collection, save or clear the
current test, or print the current test as it stands.
(The Test commands do not allow access to stored
data. You have to go to Data for that.)
2.2.1 Test Status
To see the status display, enter the Test Status
command. Press [MENU], [ENTER], [ENTER]
On the LCD display, you will see:
0501 Idle Sniff
00:30:00 00000
On the upper left, you see the current run number/
cycle number (0501 - run 05, cycle 01.).
The middle shows the detector status (Idle or
Live), and the upper right gives the current test
mode (Sniff, Normal or Grab). (Note that in Auto
mode, the indication will change from Sniff to
Normal after three hours of measurement.
Lower left shows the count-down timer (00:30:00
= 30 minutes) which counts down to zero when
the detector is Live (i.e., a test is in progress).
The lower right shows the total number of counts
since the beginning of the current cycle.
The arrow keys may now be used to access
additional status information.
Press ➔once, and you will see something like
this:
Last reading:
0409 1.80 " 0.74 p
The lower left is the run number (2 digits) and
cycle number (2 digits) of the last completed
cycle stored to memory.
The lower right is the radon reading and statistical
uncertainty, followed by "p", indicating
Chapter 2
16

picoCuries/liter, or "b" for Becquerels/cubic
meter.
When a cycle ends, the information on this
display is updated. If there have been no readings
yet, the display will show
No readings yet.
Press ➔once again, and now you will see
something like this:
24.8°C RH:3%
B: 6.36V P: 00mA
Top left is the internal temperature. (To change
from Celsius to Fahrenheit, see Setup Units.)
Top right shows the internal Relative Humidity
reading. When testing, maintain this value at 10%
or less, by using the desiccant.
Bottom left is the battery voltage. This should
range from about 6.00 to 7.10. A discharged
battery (less than 6.00 V) should be recharged as
soon as possible. A fully charged battery will rest
at 6.40 to 6.50 V. During a recharge, the voltage
will eventually rise above 7.00 V. At no time
should this read higher than 7.20 V.
In the lower right is the pump current. This
number should vary from 00mA (pump off) to
80mA. When the pump is running with a light
load, the current will range from 40-70mA. When
the pump is running with a heavy load (clogged
filter or blocked hose), the current will go to
90mA or higher. Pump currents above 90mA are
considered a sign of trouble. Try changing the
filters and check for blockage.
Press ➔again, and you will see something like
this:
HV: 2218V, 10%
L: 02 S: 0.21V
This is a display of diagnostic values. Ordinarily
it will be of little interest to you.
The top line is the high voltage reading and duty
cycle. The range of normal values is from 2000
to 2500V, and from 8% to 18%.
The lower left corner is the leakage current. At
room temperature, this value will normally range
from 0 to 10. Higher temperatures ordinarily
cause this value to rise. Excessive leakage current
will result in "noise" in the lower energy end of
the spectrum, and will also cause broadening
of the alpha peaks.
The lower right corner is the signal voltage from
the analog circuit. This number should be
"stable"; that is, fluctuations should be no more
than " 0.05V from the average value.
Press ➔yet again, and you will see something
like this:
w | cpm | +/- | %tot
A | 6.0 | 4.3 | 48.8
This is the display for the A window data. You
may press ➔to advance to B, C, D, etc.
The RAD7 records 8 windows (A - H) every time
you make a measurement. They separate counts
due to daughters of radon and thoron, and the
background. Specific alpha particles end up in
specific windows.
W: The window letter.
cpm: The counts per minute observed in the
window.
+/-: The statistical uncertainty of the cpm value,
also in units of cpm.
%tot: The number of counts in the window as a
percentage of the total counts in the spectrum.
This tells you quickly where the majority of the
counts are: In the 3-minute radon peak (window
A), or the long-lived radon peak (window C), etc.
As always, you press the [MENU] key to exit this
display and return to the start of the menu.
2.2.1a Quick Save-and-Restart
This function allows the user to end a sniff test,
store it to memory, and start up a new sniff test,
all using a single key. It operates only from the
SNIFF mode.
From the status display (showing the countdown
timer), press the ENTER key once. The display
will show:
Save and restart
? Yes
Chapter 2
17

Press the ENTER key once more to confirm your
intention. To escape, push the MENU key or
push an arrow key to select “No” and push
ENTER.
2.2.2 Test Start and Test Stop
To start testing (or "counting"), after you have
chosen the required setup, go to >Test Start by
pressing [MENU], [ENTER], [➔], and then
[ENTER].
The display will indicate that counting has begun:
Start counting.
One second later, the Status display will appear
with the countdown timer in motion:
0501 Live Sniff
00:29:37 00001
When the countdown reaches zero, the RAD7 will
automatically calculate the radon concentration,
store (or "save") the counts to memory, and clear
the counters to begin a new cycle.
To interrupt the measurement, go to >Test Stop
by pressing [MENU], [ENTER], [➔], [ENTER].
The display will respond:
Stop counting
After one second, the display will go back to the
top of the menu >Test.
You may wish to examine the Status display to
verify that the status is Idle.
To resume testing from exactly the same point in
the cycle where you stopped, select >Test Start as
described above.
Note that Stop does not terminate the run, it is a
pause. If you do not wish to resume testing from
the same point, you should select either >Test
Save or >Test Clear before continuing. This will
terminate the suspended test, store it to memory
(Save) or wipe it out (Clear), and clear the
counters to begin a new run.
2.2.3 Test Save
The >Test Save command suspends counting and
saves the suspended test (test-in-progress) to
memory as if it had reached completion. Test
Save completes the current run, so any subsequent
test data will be stored as a new run. The display
momentarily shows the run and cycle number in
the form of 0101 Saved. This command may be
accessed whether the status is Live or Idle. It
always leaves the status Idle.
You will find this command especially useful
when you wish to move the instrument to another
location without waiting for the countdown to
reach zero, but without losing that last incomplete
cycle. The calculated radon concentration from
the incomplete cycle is still good.
2.2.4 Test Clear
The >Test Clear command causes counting to be
suspended and the current run to be completed
without saving the last (suspended) incomplete
cycle. Subsequent test data will be stored as a
new run. You must answer Yes to the question Are
you sure? in order to activate this command.
This command may be accessed whether the
status is Live or Idle. It always leaves the status
Idle.
2.2.5 Test Purge
The >Test Purge command suspends counting and
begins purging the detector. The pump begins
running and the high voltage circuit turns off in
order to clear the sample chamber of radon gas
and daughters as quickly as possible. You must
provide clean, desiccated, radon-free air to the
inlet in order to push out any radon that was
previously sampled. Outdoor air is usually
adequate for this purpose.
As always, use the inlet filter and drying tube.
Ten minutes is usually sufficient for bringing the
background down after exposure to moderate
amounts of radon.
In order to dry out the RAD7 without using up
much desiccant, connect the hoses from the
RAD7 to the drying unit, as a loop. When the
pump runs, the same air will circulate repeatedly
through the desiccant. This procedure will
efficiently remove residual moisture from the
RAD7. This does not introduce any fresh air, and
so does not change the radon level in the
instrument, but you can make a measurement of
Chapter 2
18

the background while it is set up in this
configuration.
To end the purge, answer Yes to the question Stop
purge? which appears on the display.
Alternatively, you may push [MENU] to end the
purge.
2.2.6 Test Lock
If you push [ENTER] when this is displayed, it
will lock the key pad. The LCD display will just
show:
DURRIDGE RAD7
Nobody will be able to unlock the key pad, unless
they know the secret.
If the key pad was locked during a measurement,
then the readings will continue as normal, with
the RAD7 recording all the data, until the end of
the run.
Switching the unit off, while locked, will stop the
measurement, but the key pad will still be locked
when the RAD7 is switched on again.
To unlock the key pad, hold the [ENTER] and
both arrow keys down, all together, for 3 - 4
seconds, or until the unit beeps, then release the
three keys and push [MENU] immediately.
2.2.7 Test Sleep
The >Test Sleep command allows you to turn off
most of the electronic circuits, with the power
switch on, in order to conserve battery charge. A
fully charged RAD7 should be able to "sleep" for
about one week on batteries alone. Press the menu
key to "wake up" the RAD7.
The Sleep function was for older models that did
not have the Real Time Clock (RTC) and Non-
Volatile Memory (NVRAM) options. New and
upgraded instruments may be shut down
completely, power switch off, without losing any
stored data or clock.
2.2.8 Test Print
The >Test Print command calculates results for an
incomplete or suspended test cycle and prints
them according to the print format that is
currently set.
Spectrum output is available by selecting >Setup
Format Long beforehand.
If you wish to abort printing, press the menu key.
The run number and cycle number that ordinarily
appear on printed data are replaced by 0000 to
signify that the cycle is not completed.
2.2.9 Test Com
The >Test Com command outputs the results for
an incomplete test cycle to the serial port.
If you wish to abort output, press the menu key.
The run number and cycle number that ordinarily
appear with the data are replaced by 0000 to
signify that the cycle is not completed.
2.3 Data
The Data group of commands retrieves data from
memory, displays it, prints it, reports it
graphically, and outputs it to the serial port. The
Data group also includes commands for managing
memory. The memory will hold the data for
1,000 cycles, in up to 100 runs
Many commands in the Data group require you to
enter a two-digit run number after the command.
The "default" run number (the one automatically
set if you do nothing) is the run number of the last
complete cycle of data stored. The arrow keys
allow you to select any other run number.
2.3.1 Data Read
Select >Data Read followed by a two-digit run
number, to examine radon readings from that
particular run. For example, select >Data Read
01 to examine readings from run number 01, the
first test in memory.
You will see something like this:
0101 23.3 " 1.54 p
11:45 19-MAY-99
Line 1 is the run/cycle number followed by the
radon concentration, uncertainty, and unit
indicator. This example shows:
Run 01, Cycle 01, 23.3 " 1.54 pCi/L.
Chapter 2
19

Line 2 is the time (24-hour military time) and date
the reading was completed.
Press [➔] to advance to the next reading in
memory; press the backward arrow to go back to
the previous reading.
To quit examining data, press [ENTER] or
[MENU].
Note that large numbers are presented in
shorthand notation. The symbol “K” stands for
1,000 and “M” stands for 1,000,000. For
example, 33K2 stands for 33,200.
2.3.2 Data Print
To print out a run of data from memory, select
>Data Print followed by the two-digit run number.
For example, to print the data from run number
05, select >Data Print 05.
If the printer format has been set to Short, the
following printout will be made for each cycle of
the run:
0501 2.69 " 2.83 p Sniff
FRI 21-MAY-99 19:41
26.8 EC RH: 7% B:7.06V
Line 1 is the run/cycle number, the radon
concentration, the uncertainty, the units indicator
(p=picoCuries per liter, B=Becquerels per cubic
meter), and the mode indicator.
Line 2 is the date and time that the cycle was
completed and stored to memory.
Line 3 is the temperature (in either "C" Celsius or
"F" Fahrenheit), relative humidity (internal), and
battery voltage at the time the cycle ended.
If the printer format has been set to Medium or
Long, then you will see a printout like this for
each cycle:
0501 2.69 " 2.83 p Sniff
FRI 21-MAY-99 19:41
26.8 EC RH: 7% B:7.06V
Total Counts: 42.
Livetime: 27.8min
A: 0.53"0.08 cpm 47.3%
B: 0.02"0.02 cpm 1.7%
C: 0.52"0.08 cpm 46.4%
D: 0.01"0.02 cpm 0.9%
O: 0.04"0.03 cpm 3.6%
Lines l, 2 and 3 are the same as in Short format,
as outlined above. Line 4 is the total number of
counts detected during the cycle.
Line 5 is the livetime, the time that the detector
was actively collecting data.
Lines 6 through 10 are the windows data for
windows A, B, C, D, and O. (O is the
consolidated window for "others", or counts that
are not included in windows A through D.)
Each line of windows data contains the window
letter (A, B, C, etc.) followed by the window's
counts per minute (cpm), statistical uncertainty of
the counts per minute, and percent of the total
counts included within that window.
NOTE: The RAD7 does not store spectra from
old cycles, so no spectra will print from memory
even if the printer format is Long. If you need a
spectrum, be sure you print while the test is still
running.
If no data are available to print, the RAD7 will
beep and display No tests stored.
To abort a printout, press the menu key, then press
the printer paper advance button.
2.3.3 Data Com
The RAD7 has an RS232 port that can transfer
data to your computer. Status must be Idle.
To send a run of data to the serial port, select
>Data Com followed by the two-digit
run number. When ready, push [ENTER].
The following message will appear
on the display as the data is sent:
Data transfer ...
When the data transfer finishes, the RAD7 will
beep.
To enable your PC to receive data, appropriate
software should be running. A terminal emulation
program, or CAPTURE, the data link software
provided with the RAD7, may be used. See the
Chapter 2
20