Durridge Company, Inc. products

The DURRIDGE RAD7 is a truly versatile radon detector of mature and yet still state-of-the-art design. Its specifications 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 RAD H₂O is an accessory for the RAD7 that enables you to measure radon in water over a concentration range of from less than 10 pCi/L to greater than 400,000 pCi/L. By diluting your sample, or by waiting for sample decay, you can extend the upper range to any concentration.

The RAD AQUA is an accessory for the DURRIDGE RAD7 scientific radon detector that enables the continuous monitoring of radon in water such as groundwater, lakes, rivers, and other aquifers. It is used to bring the radon concentration in a closed air loop into equilibrium with the radon concentration in a flow-through water supply. The RAD AQUA consists of a spray chamber, called an “exchanger”, that brings the air and water into equilibrium. The radon in the air is monitored continuously by the RAD7.

When measuring radon underground, it is essential to collect samples without exposing them to the outside air. We offer two heavy-duty soil probes for this purpose: the Hardened Steel Soil Gas Probe, and the AMS Stainless Steel Soil Gas Probe. The specifications of these two soil gas probes are listed below:

The RAD7 radon monitor works most effectively when the incoming air sample has a low relative humidity. The DURRIDGE DRYSTIK Model ADS-3 transfers moisture from the incoming air to the air being pumped out of the RAD7. As the air enters a drying unit (not included) on its way to the RAD7, it will have already lost most of its moisture, greatly extending the life of the desiccant in the drying unit. In certain cases the need for desiccant is eliminated altogether.

The Big Bottle System is an accessory for the RAD7 that enables users to measure radon in 2.5L water samples with high sensitivity. The lower limit of detection is well below 1 pCi/L (40 Bq/m³) radon concentration in water. The upper operating limit is 10,000 pCi/L (400,000 Bq/m³). For ranges higher than that, the standard RAD H₂O accessory is recommended.

The Natural Rock Sample is a 21oz (600g) sample of granite gravel, enclosed in a container that may be sealed using a pair of ball valves and end caps.

DURRIDGE offers two categories of emission chambers: Bulk Emission Chambers, and Surface Emission Chambers. Used with the RAD7 radon detector, these products make it possible to measure radon emissions from artifacts, and ground surfaces, respectively.

The DURRIDGE Water Probe is used to collect radon samples from large bodies of water. The probe consists of a semi-permeable membrane tube mounted on an open wire frame. The tube is placed in a closed loop with the RAD7.

The Range Extender mixes fresh air with sample air to reduce the concentration of radon in the air fed to the RAD7 radon detector by an order of a magnitude, greatly increasing its effective range. The extender consists of two parallel capillary tubes joined at one end to the outlet hose connector. Fresh air is fed to the input of one tube while the incident radon sample is fed to the other. A differential pressure sensor across the two tube inputs, with a needle valve for adjustment, is used to ensure that both capillary tubes have the same pressure drop across them.