ND-2

The Sable Systems ND-2 gas sample dryer is a breakthrough for anyone who needs to dry a sample gas stream prior to gas analysis - but who does not want to mess with dusty, inconvenient, expensive, and sometimes toxic scrubber chemicals. 

Most forms of gas analysis require the scrubbing of water vapor from the airstream, because the water vapor dilutes the measured gases. Scrubbing water vapor usually requires chemicals that require frequent replacement. In addition, scrubber chemicals can interact with analyzed gas species, such as CO2 (Drierite is especially troublesome in this regard). The ND-2 is an economical and efficient alternative to scrubber chemicals in the medium to long term, and does not interact with anything but water vapor. The ND-2 can dry air saturated with water vapor at 25C to a dewpoint of -10C, corresponding to a water vapor pressure of 0.26 kPa, which is negligible in most applications. Even if completely dry air is required, using the ND-2 as a pre-scrubber will greatly reduce the amount of scrubber chemicals consumed.

The ND-2 gas sample dryer uses no chemical scrubbing agents. Instead, it uses a strongly polar polymer film that is impermeable to oxygen, nitrogen and carbon dioxide, but is hardly there as far as water vapor is concerned. By creating a strong negative pressure on one side of the membrane, and by using countercurrent exchange principles, the ND-2 gas dryer selectively removes water vapor from the sample stream with very high efficiency - without using expendable chemicals, without interacting with other gases, and without adding significant volume to a gas analysis system.