Powered by Nafion™ tubing, Perma Pure gas dryers selectively remove water from a gas sample. This selectivity for water vapor allows our dryers to remove more moisture than other gas drying solutions, while keeping analytes in the gas sample.
Monotube Dryer Series (MD-Series) gas dryers contain a single Nafion™ tube. The MD-Series can dry a gas to humidity levels as low as –40 °C dew point and is ideal for applications with flow rates up to 4 lpm.
How it Works
Flow your sample gas through the Nafion™ tubing and flow a dry purge gas outside the Nafion™ tubing, countercurrent to the sample gas flow.
While the partial pressure of water in the purge gas is less than in the sample gas, Nafion™ polymer will selectively transfer water and water vapor from the sample gas across its membrane and into the purge gas flow, yielding a drier sample gas at the sample gas output.
MD-050 Model: Flow rates up to 0.2 lpm
MD-070 Model: Flow rates up to 4 lpm
MD-110 Model: Flow rates up to 4 lpm
The performance curves above are based upon a sample inlet dew point of 20°C and purge flow rate of 2x the sample flow rate. Consult our team for operation with sample gases condensing above ambient temperature.
psid (psi-differential) = [sample gas pressure at inlet (psig)] – [sample gas pressure at outlet (psig)], based on atmospheric pressure at outlet.
| Nafion™ Tubing Outer Diameter Options | 0.050″ (MD-050), 0.070″ (MD-070), 0.110″ (MD-110) |
| Max. Flow Rate | 0.2 lpm (MD-050), 4 lpm (MD-070), 4 lpm (MD-110) |
| Housing Materials Available | Polypropylene, Fluorocarbon, or Stainless Steel |
| Max. Operating Temperatures | 80 °C for polypropylene housing, 100 °C for fluorocarbon or stainless steel housing |
| Sample Gas Port – End Fitting Options | Port 1/16″ Compression (MD-050, Stainless Steel Only) |
| Port 1/8″ Compression (All models) | |
| Port 1/4″ Compression (MD-070, MD-110) | |
| Purge Gas Port – End Fitting Size | Port 1/8″ Compression (MD-050) |
| Port 1/4” Compression (MD-070, MD-110) | |
| Purge Gas Recommendations | Purge gas must be drier than sample gas |
| Purge gas can be instrument quality air (max -40 °C dew point) or nitrogen | |
| Purge gas should flow at 2 or 3 times the sample rate | |
| *Alternate methods to using a purge gas are possible, such as recycling the dry sample gas, or pulling vacuum through the purge gas flow path. See website for more information. | |
| Coiled Configurations | Certain models are shipped coiled based on length. See page 4 for nominal diameters. Contact us for custom coiled solutions. |