Perma Pure’s Heated Monotube Gas Sample Dryer for Hot Gas Streams With High Water Content

Perma Pure’s heated MDH-Series gas dryers were specifically created to dry gas samples with dew points higher than ambient temperature without requiring separate heating elements or insulation. The higher operating temperature also allows for a faster water transfer at the inlet. Proprietary Nafion™ polymer technology selectively removes only water from sample gases, leaving the rest of the gas sample unaffected. Unlike chillers and condensers, Perma Pure’s MDH dryers remove water directly from the vapor phase, preventing the loss of water-soluble gases through dissolution in condensate.
Designed to handle gas flows of up to 1.5 lpm, the heated MDH-Series gas dryers can dry gases with as much as 30% water by volume. The compact design can be incorporated easily into analyzer cabinets or used as a stand-alone device. Specifications are shown in the table below.
Product Features:

  • Flow rates up to 1.5 l/m
  • Operating temperatures to max. 80° C
  • Operating pressures to 100 psi (absolute)
  • Corrosion resistant
  • Standard dew points to as low as – 10° C
  • No loss of analytes
  • No moving parts


Model Number


Nafion™ Tube OD/ID



96 inches

Nafion™ Tubing Dryer Housing




Thermostat Set Point

80° C

Voltages Available

115 or 220 VAC

Power Requirements

0.3 Amps, 30 Watts

Perma Pure has created a series of short video presentations to describe the basic functionality of some of our products. The videos are posted below.

Perma Pure MD, MRD and MDH Gas Sample Dryers – Full Presentation

Nafion™ Tubing Basic Functionality

Perma Pure MD and PD Gas Sample Dryers Basic Functionality