Restek
Home / Resource Hub / ChromaBLOGraphy / Gas Generators – Part 1 – Hydrogen Generators

Gas Generators – Part 1 – Hydrogen Generators

9 May 2023

Is your lab or business thinking about purchasing a hydrogen gas generator and would like to know more about the different models available from Restek and the maintenance they will require?  If so, hopefully this post will answer many of your questions/concerns.

But before we get started, have you ever wondered how a hydrogen generator works? 

Generally speaking, deionized water is introduced into a cell which consists of an anode (positive side) and a cathode (negative side).  At the anode, electricity splits the water molecules into oxygen and positive hydrogen ions (H+) via electrolysis.  A PEM (Proton Exchange Membrane) separates the anode (positive) and cathode (negative) electrodes.  Most of the oxygen molecules are vented to atmosphere while the positive hydrogen ions are drawn through the PEM towards the negative cathode electrode and via reduction (addition of electrons), the hydrogen ions (H+) become hydrogen molecules (H2). 

You may be asking yourself, for the hydrogen generators which are listed as PD in addition to the PEM, what does PD represent?  PD represents a palladium purifier module, which helps to remove the trace amounts of oxygen molecules which were not initially vented (as described above) and have made their way through the PEM.  For this reason, Restek recommends a PEMPD hydrogen generator when the hydrogen gas must be exceptionally pure, such as when used for GC carrier gas.

Several years ago I wrote a blog post which provided suggestions for selecting a hydrogen generator.  Need some help choosing a hydrogen generator? (restek.com)

As stated in this post, you will need to know the following information to select the most appropriate generator.

  1. Required hydrogen gas purity.
  2. Required flow rate and line pressure.

Once you have determined which type and capacity hydrogen generator will fit your needs, you will be able to determine which consumables are needed and the frequency of their replacement to properly maintain the generator.  But before we discuss the consumables, let’s begin with the water source. 

Water Source

If you selected one of the PEMPD (Proton Exchange Membrane/Palladium purifier) from Parker, on page 3 of Parker’s “Installation, Operation and Maintenance Manual” for the PEMPD generators, the specifications for water quality are provided.  According to the manual, water quality is listed as “Deionized, ASTM II, > 1MΩ, <1μS, Filtered to <100μm”. The PEMPD Hydrogen Generator manual can be found here.  TI_H2PEMPD_E_H2_Gas_Gen.pdf (parker.com)

A separate, Product Information sheet, can be found here.  PIS-Hydrogen-Generators-For-GC-and-GC-MS-1.pdf (parker.com)

 

Water produced by Restek part # 22000, Parker’s HydroGen Mate DI Water System, meets these specifications.   S3.2.016a---HydroGenMate_72-230.pdf (parker.com)

The HydroGen Mate DI Water System also meets the specifications for the PEM generators.  Unfortunately, it appears that Parker no longer offers a pdf of the User Guide for the PEM hydrogen generators on their website.  However, they do have a Market Application Publication sheet available. MAP_H2FuelGas_B.pdf (parker.com)

 

Daily System/Generator Check List

  1. Check the power ON indicator is illuminated.
  2. Check the STATUS / FAULT indicator on the control panel.
  3. Check the water level.
  4. Check the water conductivity.
  5. Check the water bottle spillage drains.
  6. Check for leaks.

 

Maintenance Kits

There are two Maintenance Kits for the PEMPD generators, a 6-month (4000 hours) and a 24-month (16000 hours).  The 6-month kit is Restek part # 22154 (Parker # MKH2PEMPD-6M) and contains the following.

  1. Deionizer cartridge
  2. 100µm water filter
  3. Two environmental filters
  4. Filter replacement tool

The 24-month kit is Restek part # 22155 (Parker # MKH2PEMPD-24M) and contains the following.

  1. Deionizer cartridge
  2. 100µm water filter
  3. Two environmental filters
  4. Filter replacement tool
  5. Tube clamp
  6. Water Pump
  7. Two fan guards

Similar kits are available for the PEM generators.  The 6-month kit is Restek part # 23070 (Parker # MKH2PEM-6M) and contains the following.

  1. Deionizer cartridge
  2. Water filter
  3. Three environmental filters

The 24-month kit is Restek part # 23071 (Parker # MKH2PEM-24M) and contains the following.

  1. Deionizer cartridge
  2. Water filter
  3. Three environmental filters
  4. Water level sensor (Float)
  5. Water Pump
  6. Desiccant cartridge
  7. Filter replacement tool
  8. Cartridge spanner (wrench)
  9. Service reset dongle
  10. 1/4” Tygon tube

A separate part number for the desiccant cartridge and spanner wrench is also available, Restek # 23069 (Parker # MKH2PEM-D).  A note on page 17 from the Parker H2PEM User Guide provides an important cautionary statement (below).

Note: The desiccant cartridge should be changed as and when required, however it is recommended that it is changed at least every 6, 4, and 2 months on the H2PEM-100 / H2PEM-165, H2PEM-260 and H2PEM-510 respectively.

To summarize, owning a hydrogen generator does require a brief daily inspection and maintenance every 6-months (or 4000 hours of use).  For the PEM generators, the desiccant cartridge may need replaced more often, depending on the model. 

I hope you have found this informative.  Keep watching for additional installments of gas generators.  Thank you.