Perma Pure’s Monotube Dryer for Most OEM and Laboratory Applications
Perma Pure MD™-Series gas sample dryers (Monotube Dryer) use a single Nafion™ tubing selectively permeable membrane to continuously dry gas streams removing only water vapor. These dryers operate over a wide range of temperatures, pressures and flow rates, and dry to dew points as low as -60°C.
- Flow rates up to 4 l/m
- Operating temperatures to max. 120° C
- Operating pressures to 100 psi (absolute)
- Straight or coiled configuration
- Corrosion resistant
- Standard dew points to – 25° C, with – 60° C possible in special cases (contact factory)
- No loss of analytes
- No moving parts
Principle of Operation
MD-Series gas dryers transfer moisture from one gas stream to a counter-flowing purge gas stream, much like a shell-and-tube heat exchanger transfers heat. Water molecules migrate through the Nafion™ tubing wall, transferring from the sample gas to the purge gas stream. The differential in the partial vapor pressure of water between the two gas streams drives the reaction, quickly drying the air or gas. Purge gas should be dry (-40°C dew point) air or other gas. If no dry gas is available, the differential in the water vapor pressure can be created by pulling a vacuum on the purge side by using a portion of the gas dried by the MD-Series dryer as the purge gas in a split-stream or reflux method. Visit the Purge Gas Configurations page to learn more about the purge methods Perma Pure customers deploy in their equipment.
MD Series Flow Diagram