The DURRIDGE DRYSTIK is available in two models: the Active DRYSTIK and the Passive DRYSTIK. The Active model comes bundled in an enclosure containing a built-in pump, while the Passive model relies exclusively on the RAD7's internal pump. Each model is available with three lengths of tubing, with the greater lengths permitting increased preservation of desiccant.

In typical conditions, the 12" Passive DRYSTIK will preserve a container of desiccant for two months of continuous use, a significant improvement over its standard useful life span of 10 days. The 48" Active DRYSTIK, by comparison, will preserve the desiccant for over three months. DURRIDGE also offers a premium 144" option.

Both the Passive and the Active DRYSTIK models operate on a principle involving two tubes, one inside the other. The inner tube is made of NAFION, a Teflon based material that permits the movement of water molecules, while blocking air and radon. The air sample flows along the inner tube on its way to a drying unit (not included), while the space around the inner tube is purged with dry air coming from the outlet of the RAD7.

DRYSTIK Configuration

The 12-inch Passive DRYSTIK consists of open tubing, with a wand-like handle that can be aimed at possible radon sources. One end of the tubing is attached to the inlet of the drying unit. The longest piece of tubing is attached directly to the outlet hose connection on the RAD7. The shorter lengths of tubing at the other end of the DRYSTIK are positioned to inhibit the diffusion of moist ambient air into the tubes of the DRYSTIK. The two air streams flow in opposite directions, so that the sample air leaves the DRYSTIK from the same end that the dry air from the RAD7 enters.

The 12-inch Passive DRYSTIK is unique in that it is the only model with exposed tubing. All other DRYSTIK models are housed in a compact enclosure. It is easy to set up these DRYSTIKs, as shown in the diagram below.

 Active DRYSTIK Configuration

Summary of Benefits

The DRYSTIK enables users to enjoy the full capabilities provided by the superior RAD7 technology, with its rapid response and recovery, vanishingly small background, thoron specific sniffing, and radon-in-water accessories, with the need to replace and/or regenerate the desiccant only after a long period. The cost of replacing used desiccant with new Drierite becomes insignificant.

With a pump upstream and a needle valve downstream of the NAFION tube, compressing the air inside the tube, the Active DRYSTIK works regeneratively, and can even eliminate the need for desiccant altogether.

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