Perma Pure’s Humidifier for Flow Rates up to 40 lpm, Using Liquid Water in Water to Gas Operation

Perma Pure MH™-Series humidifiers use exclusive Nafion™ tubing selectively permeable membrane tubing and liquid water to continuously humidify gas streams. These humidifiers operate over a wide range of flow rates, and humidify up to 98% RH using de-ionized water as the humidification source.
Product Features

  • Humidify gas streams in the water to gas mode
  • Humidity can be adjusted by varying the water temperature or the gas flow rate
  • Humidity up to 98% RH
  • Flow Rates up to 20 l/min.
  • Operating temperature: 0 – 80 C
  • Maximum operating pressure: 80 psi
  • Maximum differential pressure: 10 psi
  • Corrosion Resistant – Available in Polypropylene, Fluorocarbon and Stainless Steel
  • Sterile

Principle of Operation
The MH-Series gas humidifiers are tube-in-shell moisture exchangers that allow the transfer of water vapor between a liquid water supply and a gas stream. The water is absorbed into the walls of the Nafion™ tubing and then is transferred as a vapor to a dry gas stream. The liquid water is transported to the inside wall of the Nafion™ tubing, where is is vaporized into the gas stream being humidified. Because vaporization is endothermic, the humidifier either needs to be heated to a constant temperature, or the water needs to be circulated and heated to a constant temperature to ensure consistent humidification performance. Note: for gas to gas humidification, choose the FC or MD Series.
Intelligent Product Numbering System
Perma Pure offers the MD-Series dryer with three sizes of Nafion™ tubing and in a variety of lengths and connection types. Choose the size based on your flow rate and dryness requirement and build your MD dryer according to the selection guide and the part number table below:

1 – Series
MH (Monotube Humidifier) Series MD
2 – Tubing Size (OD/ID)
0.050″ Nafion™ Tubing (0.053″/0.042″) 050
0.070″ Nafion™ Tubing (0.072″/0.060″) 070
0.110″ Nafion™ Tubing (0.108″/0.086) 110
3 – Dryer Lengths
12″ (30 cm) 12
24″ (60 cm) 24
48″ (120 cm) 48
4 – Shell and Connector Material
Polypropylene (PP) P
Fluorocarbon (FEP / PVDF) F
Stainless Steel S
5 – Sample Gas Connector Type
1/16″ Compression (MD-050 only) 1
1/8″ Compression 2
1/4″ Compression 4


Listed below are the performance curves for the MH-070 Humidifiers. Perma Pure offers an MH-110 which has a slightly larger ID. The performance is similar. The MH-110 could expect to see about a 3 degree higher outlet dew point than the MH-070. The MH-110 should be chosen when a lower pressure drop is desired.


Short Video Presentations

Perma Pure has created a series of short video presentations to describe the basic functionality of Nafion™ Tubing and our Gas Humidifiers. The videos are posted below. View the Nafion™ Tubing video before moving on to the Humidifiers.

Nafion™ Tubing Basic Functionality

Perma Pure Humidifiers Basic Functionality

The MH-Series humidifier performance curves were performed under the following conditions:

  • Water was supplied to the shell side of the humidifier with a static pressure of 5″ water column and no flow.
  • The water temperature was controlled at the levels noted on the curves.
  • The humidifier housing was insulated.
  • The air was passed through the tube side of the humidifier at atmospheric pressure.
  • The inlet air stream was at 24°C and <-40°C dew point.
  • Measurements were taken with an EG&G chilled mirror dew point monitor.

For setup instructions, see the pdf Manual.

Model Number A B C D E A D E
Single Tube of 0.050″ O.D. Nafion

Fluorocarbon or Polypropylene

Stainless Steel

MH-050-12 1/8″ 1/8″ 1/8″ 14″ 10-5/8″ 1/8″ or 1/16″ 14″ 11-1/2″
MH-050-24 1/8″ 1/8″ 1/8″ 26″ 22-5/8″ 1/8″ or 1/16″ 26″ 23-1/2″
MH-050-48 1/8″ 1/8″ 1/8″ 50″ 46-5/8″ 1/8″ or 1/16″ 50″ 47-1/2″
Single Tube of 0.070″ O.D. Nafion Fluorocarbon or Polypropylene Stainless Steel
MH-(070 or 110)-12 1/4″ or 1/8″ 1/4″ 1/4″ 14-1/4″ 10″ 1/4″ or 1/8″ 13-3/4″ 10-3/4″
MH-(070 or 110)-24 1/4″ or 1/8″ 1/4″ 1/4″ 26-1/4″ 22″ 1/4″ or 1/8″ 25-3/4″ 22-3/4″
MH-(070 or 110)-48 1/4″ or 1/8″ 1/4″ 1/4″ 50-1/4″ 46″ 1/4″ or 1/8″ 49-3/4″ 46-3/4″