Real-time Continuous Radon Monitor with Spectral Analysis

The DURRIDGE RAD7 is a truly versatile radon and thoron detector used by research scientists and professionals worldwide. Its mature and yet still state-of-the-art design match or exceed those of the most expensive radon measurement devices in the world. At the same time, it incorporates a number of exclusive features that are found in no other radon detector, regardless of price. Incredibly, the RAD7 is affordable.

The RAD7 is a sophisticated measuring instrument widely used in laboratories and research work around the globe. It is used by professional radon testers, mitigators and home inspectors, as well as by research scientists studying groundwater, mines, deserts, the ocean and volcanoes at extreme temperature. A rugged carrying case encloses the instrument, ensuring reliability in the field.

The RAD7 is the easiest electronic radon detector to use, with preprogrammed setups for common tasks. The instrument comes complete with a built-in air pump, rechargeable batteries, and a detachable wireless printer. The RAD7 can store large amounts of radon data for later printing and/or for graphing and analysis on a computer using DURRIDGE’s powerful and free CAPTURE software.

The RAD7 is a Sniffer that detects the 3-minute alpha decay of a radon daughter, without interference from other radiations. It also detects the instantaneous alpha decay of a thoron daughter for rapid thoron measurements. The instrument can sniff for entry points and radon gushers, and it recovers from high radon exposures in minutes. The RAD7 is also a Continuous Radon Monitor which can measure the EPA action level of 4 pCi/L, with 10% standard deviation, in under two hours. At the end of each run, the detector prints out a complete report.

The included accessories are sufficient for the measurement of radon and thoron in air. Additional, optional accessories are available for the measurement of radon in soil gas and water, for the measurement of the emission of radon from surfaces, objects and bulk materials, and for other specialized applications. See the Products Overview page for details.

RAD7 Advantages

Precision and Performance

  • Fastest response and recovery times of any electronic monitor/sniffer on the market.
  • Measures EPA action level of 4 pCi/L in under two hours.
  • Recovers from radon highs in minutes – not hours.
  • Spectrum printout verifies correct operation of instrument in field.

Convenience and Ease of Use

  • All-in-one complete, compact, portable unit in rugged carrying case.
  • The instrument directs you step by step, so you can do what you want to do.
  • Programmed set-ups for often-used tests.
  • Audible radon and thoron counts lets you hear the hot spots.

Security and Flexibility

  • Tamper-proof key-lock command secures your RAD7 and assures uninterrupted testing.
  • Easily portable: The RAD7 weighs 9.6 pounds (4.35 kg).
  • Displays, prints, and downloads radon data in your choice of units.
  • Immunity to build-up of 210pb.

Expandability and Value

  • Includes wireless printer and infrared data link for on-the-spot printouts.
  • Available with a wide range of optional accessories for measuring radon in water and below ground.
  • Versatile connectivity with an RS-232 port and USB adaptor
  • Includes CAPTURE software for data retrieval and analysis. Full Windows and macOS compatibility.
  • Includes rechargeable batteries and extensive documentation.

Testing for radon in soil gas with the RAD7. Research conducted by Kizito M. Opondo, Kenya Electricity Generating Co. Ltd.
Testing for radon in soil gas with the RAD7. Research overseen by Kizito M. Opondo, Kenya Electricity Generating Co. Ltd.

Geologist Kenneth Sims using a RAD7 on the rim of a volcano. Photo by John Catto.
Geologist Kenneth Sims using a RAD7 on the rim of a volcano. Photo by John Catto.

Operating the RAD7

The RAD7 is remarkably easy to use. When you turn it on you will see current settings listed on the LCD display. This allows you to check that the instrument is configured as needed for your intended use. Presets are available for 1-day and 2-day tests, and you can also establish a custom preset for your particular job. When you arrive at the testing site just select a preset and the RAD7 will start collecting data immediately.

An exclusive RAD7 feature is the ability to automatically switch between “Sniff” and “Normal” modes. The instrument starts in “Sniff” mode, providing a quick response, base-line reading. After 3 hours enough radon progeny will have accumulated on the detector for the RAD7 to be able to switch to “Normal” mode, providing higher statistical precision.

Once started, the RAD7 can be “locked” to prevent it from being tampered with until you return. When the RAD7 is locked it will become unresponsive to user input, but the radon test in progress will continue without interruption.

Alpha Energy Spectrum from RAD7

Alpha Energy Spectrum from RAD7

RAD7 Standard Setup Diagram

RAD7 Standard Setup Diagram

The RAD7 comes with all of these components and accessories.

The RAD7 comes with all of these components and accessories.

RAD7 with optional bluetooth adaptor

RAD7 with optional bluetooth adaptor

RAD7 electronic radon detector

RAD7 electronic radon detector

RAD7 Software
CAPTURE Software for Windows and macOS

Getting Started: 1-Day Test with the RAD7

Thoron Measurement Capabilities

The RAD7 is capable of making a direct and specific measurement of thoron, which is a short-lived isotope of radon. Testing for thoron is a great way to identify the points at which radon is entering a building, because the thoron is localized to those entry points. The RAD7’s response to thoron is virtually instantaneous, and compared to other instruments the RAD7 is much less susceptible to radon-thoron interference, thanks to its ability to distinguish the isotopes by their unique alpha particle energies. See Section 4.5 of the RAD7 Manual and the following Application Note for details:
Application Note: Sniffing for Thoron (HTML)

USB and Bluetooth Connectivity

Stored RAD7 data may be downloaded to a computer using a USB or serial connection. DURRIDGE offers a dedicated RAD7 communications software package called CAPTURE, which automatically transfers RAD7 data to disk, displays radon graphs, and produces a variety of supplementary information. CAPTURE can also monitor a RAD7 in real time with its Chart Recorder. Learn more about CAPTURE here.

For situations where the RAD7 can not be directly connected to a computer, DURRIDGE offers the Parani SD1000 Serial to Bluetooth Adaptor. This adaptor offers a 100 meter wireless range, and it comes pre-configured for plug and play compatibility with the RAD7 and CAPTURE. An optional 16 hour battery allows the adaptor to be used even in the absence of a reliable power source.

RAD7 Specifications

Modes of Operation

  • SNIFF  Rapid response and rapid recovery radon measurement

  • NORMAL  High sensitivity radon measurement

  • AUTO  Automatic switch from SNIFF to NORMAL after three hours run

  • THORON  Radon and thoron measured simultaneously and independently

  • GRAB  Analysis of air “grabbed” from a discrete sample

  • WAT  Automatic analysis of water samples with optional RAD H2O accessory


  • Radon in air with Sniff protocol for quick, spot reading

  • Thoron in air for searching for radon entry points

  • Radon in air 1-day, 2-day or weeks protocol for long term measurement

  • Radon in water batch samples with optional RAD H2O and Big Bottle System accessories

  • Continuous radon in water with optional RAD AQUA and Radon-in-Water Probe accessories

  • Radon in soil gas with optional Soil Gas Probe and DRYSTIK accessories

  • Radon emission from soil and hard surfaces with optional Surface Emission Chamber accessory

  • Bulk radon emission from bulk materials and objects with optional Bulk Emission Chamber accessory

Data Storage

1,000 records, each with 23 fields of data

Log of printer output also stored

Sample Pumping

Built-in pump draws sample from chosen sampling point

Flow rate typically 800 mL/min

Print Output

Short, Medium, or Long format data printed after each cycle

Run summary printed at end of run, including averages and spectrum

PC Connectivity

RS232 serial port, full remote control implemented in CAPTURE Software.

Optional serial to Bluetooth adaptor for wireless PC connectivity.

Audio Output

  • GEIGER Tone beeps for radon and thoron counts

  • CHIME Chime only at the end of each cycle, otherwise silent

  • OFF No sound

Tamper Resistance

TEST LOCK command locks keypad to secure against tampering

Principle of Operation

Electrostatic collection of alpha-emitters with spectral analysis

Passivated Ion-implanted Planar Silicon detector

SNIFF mode counts polonium-218 decays

NORMAL mode counts both polonium 218 and polonium 214 decays

Built-In Air Pump

Nominal 1 liter/minute flow rate

Inlet and outlet Luer connectors


RS-232 port up to 19,200 baud rate

USB adaptor is included with every RAD7

Measurement Accuracy

+/-5% absolute accuracy, 0% – 100% RH

Nominal Sensitivity

SNIFF mode, 0.25 cpm/(pCi/L), 0.0067 cpm/(Bq/m3)

NORMAL mode, 0.5 cpm/(pCi/L), 0.013 cpm/(Bq/m3)

Radon Concentration Range

0.1 – 20,000 pCi/L (4 – 750,000 Bq/m3)

Intrinsic Background

0.005 pCi/L (0.2 Bq/m3) or less, for the life of the instrument

Recovery Time

Residual activity in Sniff mode drops by factor of 1,000 in 30 minutes

Operating Ranges

Temperature: 32° – 113°F (0° – 45° C)

Humidity: 0% – 100%, non-condensing

Cycle Range

User controllable number of cycles, from 1 to 99 to unlimited, per run

User controllable cycle time, from 2 minutes to 24 hours

CAPTURE Software

  • Compatible with Microsoft Windows 7 through 10, and macOS

  • Automatic RAD7 connection and data download

  • Graphs radon, thoron, temperature and humidity over time

  • Automatic humidity correction

  • Statistical analysis tools track concentration averages and uncertainties

  • Chart Recorder mode provides real-time RAD7 status monitoring

  • Control RAD7 operations from computer via direct or remote connection

  • Automatic calculation and display of radon in water with optional RAD H2O, RAD AQUA, and Water Probe accessories

  • Automatic combination of data from multiple RAD7s

RAD7 Dimensions

11.5″ x 8.5″ x 11″ (29.5 cm x 21.5 cm x 27.9 cm)

RAD7 Weight

9.6 pounds (4.35 kg)

Shipping Dimensions

17″ x 17″ x 17″ (43 cm x 43 cm x 43 cm)

Shipping Weight

33 pounds (15 kg)

LCD Display Output

2 line x 16 character alpha-numeric display

Case Material

High density polyethylene

Infrared Printer

Omniprint OM1000 Wireless Infrared Printer included

Power Supply

11-15V DC (12V nominal) @ 1.25A, center pin positive, or included internal EnerSys sealed lead acid rechargeable battery pack (6V nominal, 30Wh, 5Ah) See RAD7 Battery Material Safety Data Sheet (PDF)

Battery Longevity

24 hours in SNIFF mode; 72 hours in Monitor mode

TechFlow ​

Alsahafa District, Prince Nassir Bin Farhan Street. Building: 4140 RIYADH, 13321 Saudi Arabia​

وقت البيانات لتقنية المعلومات شركة برمجة في الرياض الحلول الواقعية شركة برمجة في الرياض