Humidity Generators : MHG for RH and Dewpoint regulation in volumes from 10 ml up to 300 litres.

The MHG-32 and MHG-100 systems from ProUmid GmbH are flexible humidity generators.

The Modular Humidity Generator concept is extremely flexible.

With remote sensor for Relative Humidity (HR), optional temperature probes, gas injection at point of use, it can :

• provide a simple stream of gas of controlled hygrometry
• give smooth regulation of humidity or dewpoint inside a wide range of test chambers and other experimental systems
• give rapid step changes of RH
• adapt to varying temperatures
• work in restricted geometries, even in applications where it is not possible to introduce a humidity sensor.

Principle of humidity control

The MHG systems provide a flow of air with controlled hygrometry, using a capacitive RH sensor at the point of use for feedback control of the moisture supply.

The main components are :

• A remote combined humidity/temperature sensor, to integrate in the target chamber
• A controllable source of humidified gas - typically air - which is combined with dry air for rapid setpoint changes
• Feed back control, which allows the user to program a setpoint for the humidity at the point of use
• Optional features include a secondary temperature sensor, to correct for non-isothermal systems.

The principle of the MHG is to adapt to the temperature at the point of use. Temperature regulation can be imposed by the user, or the system can function at ambient temperature.

A simple humidity control application of MHG

The sensor is installed inside the test chamber, at the target position, giving a direct measurement of hygrometry.

Feedback control of the supply of humidified air to the chamber provides hygrostatic control at the point of measurement.

The MHG systems adapt to the temperature of the test environment, as measured by the sensor.

More complex installations

There are many cases where it is not possible to install a humidity sensor at the point of use, either due to lack of physical space, or due to temperature incompatibility or heat flow considerations.

It is often useful to operate the system in a multi-zone configuration, where the target zone is at a temperature different from the sensor zone. The MHG can adjust the conditions in the sensor zone in order to obtain the desired target setpoint humidity. The target temperature can be provided :

• from a direct reading by the MHG, with an optional PT-100 sensor,
• by manual input to the MHG front panel
• over the RS232 or Network communications interface, for example using LabView.

We have experience in helping people to design their humidity controlled installations. Please contact us if you would like to discuss your application.

Humidity Generator MHG32 : for precise humidity regulation of small volumes

• Compact remote vapour generator
  • attaches directly to the test system
  • immediate no-delay supply adjustment for precise regulation
  • small system volumes
  • low flow rates
  • latent heat compensation of vaporiser
• Ideal for humidity-controlled analysis and test chambers :
  • spectrometers
  • XRD diffractometers
  • microscopes
  • physical and mechanical analysers: DMA, rheometry, flowability, and other powder properties
  • analytical instruments

Humidity Generator MHG100 : for large volumes

The MHG-100 is designed for larger volumes, where large amounts of water vapour must be supplied to give rapid regulation of humidity.

• Vapour generation inside the control unit
  • for maximum vapour supply rate at high flow rates
  • chiller connection for enhanced low temperature operation
• Twin vapour supply lines
  • large vapour volumes
  • improved uniformity
  • rapid response in large systems
• Ideal for:
  • conditioning chambers and incubators
  • gloveboxes
  • larger sample transfer chambers

Feature Comparison

	MHG-32	MHG-100
Chamber volume (Note 1) :	0.02…20 Litres	1…300 Litres	typical
Flow rate :	5…500 ml/minute  (1000 on request)	0…15   litres/minute
Temperature range (Note 2) :	2…95 °C	5…90 °C
Humidity range :	2…98 %RH	5…95 %RH	at T <75 °C
Humidity accuracy :	±0.6 %RH	±0.6 %RH	(0…100 %RH at 23 °C ±5 °C )

Options and Advanced features

Software interfacing and remote triggering

The MHG can be controlled using the front control-panel buttons.

Software is also available for:

• configuration and control adjustment
• data logging and export to file
• Ramp, step and soak humidity profiles
• triggering by software or hardware inputs
• interfacing by RS232/Modbus or Ethernet

Humidity Correction for Thermal zones

When it is not possible to install a humidity sensor in the zone of interest, the sensor can be installed in a secondary area at a different temperature. The controller compensates the humidity setpoint for the temperature difference between the humidity measurement point and the target temperature, which can be measured with a secondary temperature sensor, or manually set. Please contact us for details.