Malema™ M-VF Series Adjustable Excess Flow Valves for Hydrogen Service


Hydrogen is a hazardous fluid. Gaseous hydrogen is flammable over a wide concentration range, is easy to ignite, and is nearly invisible while burning. The gas is odorless and colorless, and can cause asphyxiation or unconsciousness if released into an enclosed space. Any rupture or leak in hydrogen transfer lines has to be arrested, avoiding catastrophic accidents. Installing Malema™ M-VF series Velocity Fuses in these transfer lines would prevent such accidents, saving valuable human lives and property.

Figure 1: Typical Flame Ionization Detector

Typical Flame Ionization Detector
  • A. Sample inlet
  • B. Oven
  • C. Hydrogen gas inlet
  • D. Oxidizer inlet
  • E. Positive bias voltage
  • F. Flame
  • G. Collector plates
  • H. Signal out
  • J. Exhaust port

Application: Hydrogen carrier lines in refineries and petrochemical plants

All refineries and various petrochemical and chemical plants use process gas analyzers such as gas chromatographs and TOC analyzers. Hydrogen is used as a carrier gas in gas chromatography and in various analytical instruments, most commonly as a fuel component of combustion gases for Flame Ionization (FID) and Flame Photometric (FPD) detectors. Spark discharge analyzers and total hydrocarbon measurements also use hydrogen mixtures. Using hydrogen as a carrier gas speeds up the process of analyzing the component.

Hydrogen is supplied via tubes from a bank of cylinders and a back up generator system to the analyzer cabin/room located inside the plant where analysis is done. Hydrogen used for this purpose is of very high purity (99.99999% pure).

The Malema™ M-VF series adjustable velocity fuse is a safety device used in tubes and pipe lines carrying hazardous and expensive fluids. A rupture or leak in the fluid path downstream of the safety valve increases the velocity of the fluid beyond a predetermined set level, causing the fuse to shut off flow through the line. 

Many gas analyzer and analyzer system manufacturers use Malema™ M-VF series valves in their systems. References can be produced on request.

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Malema supplies this publication for informational purposes only. While every effort has been made to ensure accuracy, this publication is not intended to make performance claims or process recommendations. Malema does not warrant, guarantee, or assume any legal liability for the accuracy, completeness, timeliness, reliability, or usefulness of any information, product, or process described herein. We reserve the right to modify or improve the designs or specifications of our products at any time without notice. For actual product information and recommendations, please contact your local Malema representative.