DRYSTIK

The RAD8 and RAD7 radon monitors work 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 RAD8 or RAD7. As the air enters a drying unit (not included) on its way to the RAD8 or 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 DRYSTIK has at its heart a Nafion humidity exchanger with a brushless pump, fixed and variable flow limiters, and a programmable Duty Cycle Controller. These are all contained in a compact enclosure. The DRYSTIK’s pump compresses the sample air inside the membrane tubing, initiating the transfer of water molecules to the outer purge flow, drying the incoming air as it moves through the device.

The DRYSTIK is available in two enclosures: a standard case which is suitable for laboratory use, and a ruggedized Pelican case which is ideal for demanding field work. The instrument is capable of bringing the relative humidity of air flowing at 0.15 L/min down below 10% in less than four hours when operating with a 40% duty cycle, and the humidity can be maintained below 6% indefinitely without any desiccant. This allows a RAD7 to operate under optimum conditions with the highest sensitivity and lowest operating cost. At a higher flow rate of 1.2 L/min, the DRYSTIK can bring the RH down below 12%, which is sufficient for enhanced sensitivity thoron measurement.

For soil gas measurement, the DRYSTIK provides high flow capability for thoron detection. For radon, the ability to lower the flow with the built-in Duty Cycle Controller means that continuous soil gas readings may be made indefinitely, without any risk of fresh air diluting the soil gas sample by diffusing it down to the extraction point.