No risk of explosion when using hydrogen as GC carrier gas

Within the scientific community, there is broad agreement that hydrogen is the best carrier gas for capillary GC applications. But in spite of many advantages, the gas has one disadvantage: In case of a leakage, there is the possibility of an explosion in the GC oven.

To eliminate this possibility, SIM has developed a hydrogen sensor that is constantly detecting the gas concentration in the GC oven. In case of a leakage, the carrier gas is automatically switched over to inert gas so that there is no risk of explosion.

In Agilent gas chromatographs the hydrogen sensor with control board and carrier gas switching can be fully integrated. For use with most other GCs, an external device with sensor control board and carrier gas switching is available. The related gas sensor head is installed in the GC oven.

Regardless of the GC system, the hydrogen sensor is constantly monitoring the hydrogen concentration in the GC oven. Green, yellow, and red LEDs indicate the correct operation of the device (green) as well as an increasing hydrogen concentration (from yellow to red). When the first red LED flashes (approx. 0.4 % by vol. of H₂) a warning signal can be heard, and above 1 % by volume hydrogen the carrier gas is switched over to inert gas. This guarantees a high level of safety because the lower explosive limit (LEL) of hydrogen in air is 4 % by volume.

Moreover, hydrogen as carrier gas offers economic advantages because the limited helium supplies in certain geographies will increase the helium costs. In case of a carrier gas change to hydrogen, the SIM Hydrogen Sensor will guarantee safe working in the laboratory:

• continuous monitoring of the oven air
• hydrogen concentration is displayed by LEDs
• optical and acoustic alarms when preset warning limits are exceeded
• automatic switching over to inert gas when the hydrogen concentration exceeds the internal limit (1 % by vol. H₂, i.e. 25% of LEL)

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