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RAD7 Accessories


DURRIDGE offers a variety of accessories for the RAD7 radon detector. Each is explained in detail below.

CO2 Logger  CO2 Sampling Data Logger
Cool Trap  Remove moisture from air entering the DRYSTIK and RAD7
Duty Cycle Controller  Accessory for Soil Probe and DRYSTIK Model ADS-1
Indoor Faucet Connector  Adaptor for taking tap water samples
Natural Rock Sample System  Monitor RAD7 performance up to once per month
Relay Box  Accessory for issuing alerts and controlling the RAD7 operating environment
Serial to Bluetooth Adaptor  Adaptor for communicating wirelessly with the RAD7 from a computer
USB to Serial Adaptor Cable  Cable for connecting the RAD7 to a computer
Water Switch  Prevent water from entering the DRYSTIK and other sensitive devices


CO2 Logger

CO2 Sampling Data Logger


The Portable CO2 Sampling Data Logger is designed to log carbon dioxide levels in the air being fed through a RAD7. The sampling allows for elevated ambient temperatures, and relative humidity.

Inside the Sampling Data Logger is an optional battery-operated micro-pump connected to two tubing ports on the side of the unit. The unit is designed to automatically turn itself on (15 seconds up to once every 18 hours), draw gas for a programmable period from the inlet port and expelling it from the discharge port, make a measurement and store the value internally with time stamp. The data is retrieved form the unit via USB connection to a computer running the downloadable DAS software.

The battery-operated, portable Sampling Data Logger comes in five models: 1%, 5%, 30%, and 100% CO2. All models include a data cable for retrieving accumulated measurements. A backlit LCD that changes color according to CO2 levels and is programmable. Filters, fittings, tubing and auxiliary international power supply.


  • CO2 Measurement: non-dispersive infrared (NDIR).
  • Measurement Ranges:
    • 1% (0-10,000 ppm)
    • 5% (0-50,000 ppm)
    • 30% (0-300,000ppm)
    • 100% (0-1,000,000 ppm)
  • Sampling Method: Tube sampling (0.30 liters/minute
  • 15,000 measurement capacity
  • Measurement interval 15 second to 18 hours.
  • Sample pump timer (optional).
  • Sensor Life Expectancy: > 15 years
  • Calibration certificate (included)
  • Maintenance Interval: No maintenance required
  • Size: 5.75×5.6×1.3in (146×91×33mm)
  • Tubing sizes: 3/32 or 1/8"


  • LED displays CO2 in PPM for 1%, 5% and in percentage XX.YY% for 30%, 100%


  • 4 AA batteries (not included)
  • International wall power supply (included)

Included Accessories

  • USB A to USB mini cable
  • 1/8 tubing 10 feet
  • International wall mount power supply
  • Moisture trap
  • Particulate and hydrophobic filters
  • Assorted tubing fittings


  • 90 Days


CO2 Logger Manual (PDF, CO2Meter.com)

Software Support

Data Acquisition System (DAS) Software (HTML, CO2Meter.com)


Price List (HTML)


Cool Trap

Remove moisture from air entering the DRYSTIK and RAD7


The Cool Trap is a RAD7 accessory that operates under pressure in a vessel of icy water, directing air through a coil of copper tubing. This process creates condensation and removes excess moisture from the air. The Cool Trap operates upstream of the laboratory drying unit, DRYSTIK, or RAD7, to reduce the amount of moisture advancing through each.

Two versions of the Cool Trap are available: the Bucket-Sized Cool Trap and the Mug-Sized Cool Trap. The Mug-Sized Cool Trap is more portable, while the Bucket-Sized Cool Trap offers greater moisture removal due to its longer tubing. Both versions of the Cool Trap have one air inlet tube and two outlet tubes, one for outputting the dried air, and another for draining the condensed water.

Cool Trap Specifications


Mug Sized Cool Trap

Bucket-Sized Cool Trap


2.75 in (7.0 cm)

7.50 in (19.1 cm)


5.75 in (14.6 cm)

11.75 in (29.9 cm)


0.6 lbs (270 g)

3.2 lbs (1.5 kg)





Cool Trap Configuration with DRYSTIK (PDF)

DRYSTIK Manual (PDF) See Section 2.4, High Humidity Conditions


Cool Trap in Mug Photo

Bucket Sized Cool Trap Photo

DRYSTIK Configuration with Cool Trap Diagram

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Price List (HTML)

    Mug-Sized Cool Trap


Duty Cycle Controller

Accessory for Soil Probe and DRYSTIK Model ADS-1


Monitoring soil gas in the long term, for geotechnical and earthquake studies, is likely to dilute the soil gas sample with fresh air diffused down from the surface. The DURRIDGE Duty Cycle Controller can control the 12V supply to an Active DRYSTIK Model ADS-1, with a duty cycle anywhere from 100% to less than 1%. This means that the average flow rate can be carefully controlled to eliminate dilution of the sample and enable soil gas sampling to continue indefinitely.


The DURRIDGE Duty Cycle Controller controls the on and off time of a DC voltage powered device, resulting in lower power usage, lower consumption of consumable resources, and, in the case of a device with a pump, lower average flow rate. The DURRIDGE Duty Cycle Controller accepts a continually-on supply voltage between 9-15 VDC and converts it to a modulated square wave signal.

The Duty Cycle Controller has an ON time in each cycle of 3 seconds. The OFF time in the cycle may be varied from zero to 1,000 seconds or fully off.

Side benefits to reducing the flow rate include reducing wear on the Active DRYSTIK Model ADS-1 pump and increasing the life of the desiccant.

The Duty Cycle Controller can also control the power to any other 12V device, such as a sampling pump, whose current draw is not more than 1A. Thus a sampling pump may be set, by the Duty Cycle Controller, to pump for three seconds once every minute.


Duty Cycle Controller User's Manual (PDF)

Related Products

DRYSTIK Model ADS-1 Discontinued (HTML)

Soil Gas Probes (HTML)


Price List (HTML)




Indoor Faucet Connector

Adaptor for taking tap water samples


For filling RAD H2O vials or bottles, and feeding tap water into the RAD AQUA spray chamber, DURRIDGE offers an Indoor faucet connector manufactured by Claber Inc. It attaches to any indoor straight neck faucet up to 1¼ inch wide. A rubber seal clamps onto the faucet to prevent leaking or spraying, and a convenient quick-click coupler allows for fast and easy hose removal.

Connector Specifications


UV-stabilized ABS Plastic

Maximum Water Temperature

104° F (40° C)

Operating Pressure

14.5 PSI (1 Bar) to 58 PSI (4 Bar)

Leak Pressure

145 PSI (10 Bar)

Maximum Faucet Width

2.75 in (7.0 cm)

Maximum Faucet Height

5.75 in (14.6 cm)

Featured Articles

Product Comparison: Radon In Water Accessories (HTML)

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Indoor Faucet Connector in use


Natural Rock Sample System

Monitor RAD7 performance once a month.


The Natural Rock Sample system consists of a 21oz (600g) sample of granite gravel from a stone quarry, normally sold by the truckload as construction material. It is enclosed in a container that, by closing two ball valves, may be completely sealed.

Granite, in general, contains trace amounts of both uranium and thorium that has been in the rock since it was formed, millions if not billions of years ago. Therefore all the progeny of both the uranium and thorium decay chains are fully supported and in full equilibrium down to 226-Ra and 224-Ra.

The rock sample is dry and therefore constitutes a rock-steady emitter of both radon and thoron. It is possible to take advantage of that property to check the performance of a RAD7.

The device, as it stands, can provide a means for monitoring long-term changes in both radon and thoron sensitivity. After calibration at DURRIDGE Company, and with the optional Thoron Calibration Check Kit (sold separately), the device can be used for low-precision checking of both the RAD7's radon sensitivity (monthly) and its thoron sensitivity (any time). A copy of the Durridge-issued Natural Rock Sample Calibration Form can be previewed below.

Natural Rock Sample Physical Specifications

Shipping Dimensions

16" x 8" x 8" (41 cm x 20 cm x 20 cm)

Shipping Weight

5 pounds (2.3 kg)


Durridge Natural Rock Sample System User's Manual (PDF)

Sample Calibration Form (PDF)


Natural Rock Sample System Configuration Diagram (Illustration)

Natural Rock Sample System Components (Illustration)

Thoron Calibration Check Kit Components (Illustration)


Price List (HTML)

DURRIDGE Natural Rock Sample

Thoron Calibration Check Kit for Natural Rock Sample
(sold separately)


Relay Box

RAD7 accessory for issuing alerts and controlling the RAD7 operating environment


At the end of each cycle the RAD7 can compare the measured radon concentration with each of two user-specified relay thresholds. If the radon level is higher than a particular amount, the RAD7 sets a relay. If it is lower, the relay is reset.

Relays can be used to electronically trigger a warning mechanism at the lower threshold, and an alarm at the higher threshold. Relays can also be used to control ventilation equipment, or to change the concentration of radon in a sealed chamber, without the necessity of a computer.

The DURRIDGE Relay Box facilitates this communication with external instruments.


Price List (HTML)



Serial to Bluetooth Adaptor

Adaptor for communicating wirelessly with the RAD7 from a computer

RAD7 with optional Serial to Bluetooth adaptor



DURRIDGE offers an optional Serial to Bluetooth adaptor to facilitate the transmission of radon data between the RAD7 and a Bluetooth-enabled Macintosh or Windows computer running DURRIDGE's CAPTURE software. With the Bluetooth Adaptor, it becomes faster and more convenient to perform graphing and real-time data analysis. The adaptor has been tested across distances exceeding 40 meters, through walls and trees, and it is known to support 100 meter communication along uninterrupted lines of sight.

The Serial to Bluetooth Adaptor may be powered by either an included AC adaptor or an optional 3.7V lithium ion battery, which is rated for 16 hours of continuous use. The included stub antenna may be replaced with an optional 2 dBi Dipole Antenna for an extended communication range.

The Serial to Bluetooth Adaptor comes preconfigured for use with the RAD7. Printed documentation is included, explaining how to connect and reconfigure the adaptor.

Serial to Bluetooth Adaptor Specifications

Product ID


Communications Protocol

Bluetooth v2.0 + EDR


5~12VDC via standard AC adaptor or optional 3.7V 900 mAh battery with 16 hour capacity and 5 hour charge time.


76 x 31 x 16 mm without battery pack
76 x 31 x 31 mm with battery pack


24 g without battery pack
42 g with battery pack


3-year Limited Warranty


RAD7 Bluetooth Connectivity Guide (PDF)

RAD7 Software

CAPTURE Software for macOS and Windows (HTML)


Price List (HTML)



USB to Serial Adapter Cable

Adapter cable for connecting the RAD7 to a Computer


Durridge offers the StarTech USB to Serial Adaptor cable for connecting the RAD7 to your computer. This makes it possible to download, analyze, and export radon data using DURRIDGE's CAPTURE software for Windows and macOS. It is also possible to issue RAD7 commands and control the RAD7 remotely.

This adaptor cable is included with all newly purchased RAD7s, and it is also available separately.

Adaptor Cable Specifications

Hardware Chipset


Serial Protocol


Connector Types

1 - DB-9 (9 Pin; D-Sub) Female
1 - USB A (4 pin) Male

OS Compatibility

Windows XP/Vista/7/8/10
Mac OS 10.X

Cable Length

5 ft 11in (1.8m)

Power Source

USB Bus Powered

Shipping Weight

0.5 lb (0.2 kg))

Product Warranty

2 Years

Included in Package

USB to Serial Adaptor Cable
Driver CD
Instruction Manual

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Download Serial to USB Adaptor drivers

Software Drivers (HTML)


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StarTech USB to Serial Adaptor Cable


Water Switch

Prevent water from entering the DRYSTIK and other sensitive devices

DURRIDGE Water Switch


The Water Switch is a device which cuts off power to a device should water enter the switch. It is specifically designed for the DRYSTIK. The Water Switch consists of a reed switch surrounded by a float that contains a magnet. If the float rises it will turn off the switch, cutting power to the DRYSTIK's pump and preventing water from entering the device and saturing its sensitive NAFION tubing.


Water Switch Manual (PDF)


Water Switch Configuration Diagram

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Price List (HTML)

Products Accessories Services Software Support More
RAD7 Radon Detector
Big Bottle System
Water Probe
Soil Gas Probes
Range Extender
Emission Chambers
CO2 Logger
Cool Trap
Duty Cycle Controller
Indoor Faucet Connector
Natural Rock Sample
Relay Box
Serial Bluetooth Adaptor
USB to Serial Adaptor
Water Switch
RAD7 Calibration
Thoron Calibration
RAD7 Repair
Firmware Upgrades
Software Drivers
Product Manuals
Support Contacts
Video Tutorials
Research Papers
External Radon Links
Company Information
Customer Testimonials
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