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Hydrogen & Safety with Gas Chromatography Systems

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Hydrogen has long been considered the best carrier gas in gas chromatography as it provides fast analysis, higher efficiencies, reduced costs and prolonged column life. The advantages of hydrogen are clear, however as an explosive gas, an undetected hydrogen leak from a broken column or faulty connection can put your laboratory and personnel at risk. Da Vinci Laboratory Solutions has developed the DVLS³ Simply, Smart Sensor for gas chromatography systems to resolve these safety risks by providing a reliable, safe technique to detect hydrogen leaks in GC laboratories.

This is a modified lecture presented by Lenny Kouvenhoven, the Director of R&D at Da Vinci Laboratory Solutions, at the 2012 Gulf Coast Conference. The Gulf Coast Conference is a non-profit organization promoting the education and advancement of knowledge of Chemical Analysis Technology associated with the Petrochemical, Refining, and Environmental fields.

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Hydrogen & Safety with Gas Chromatography Systems

  1. 1. A Hydrogen Sensor can ensuresafety when using Hydrogen Carrier Gas in a Chromatographic System A Gulf Coast Conference Presentation Presenter: Lenny Kouwenhoven Director of Research & Development Da Vinci Laboratory Solutions Abstract #27 October 17th, 2012
  2. 2. Overview Four reasons for using H2 as a carrier gas Safety measures Hydrogen sensor Principle of operation and measurement Hardware overview Summary Contact information
  3. 3. Reasonsfor using H2 as a Carrier Gas1. Fast Analysis:  Fast diffusion rate; 4 times faster than N2  Half as viscous as helium; higher linear gas velocity and shorter retention times2. High Efficiency:  Flattest Van Deemter curve
  4. 4. Reasonsfor using H2 as a Carrier Gas3. Prolonged Column Life: □ Some applications have a lower elution temperature, therefore the column life is longer4. Cost effective: □ 3x’s less expensive than its helium equivalent □ Bottle or generator
  5. 5. Reluctant to use H2 as a Carrier Gas? Hydrogen is an Explosive Gas: Undetected gas leaks can lead to an explosion in the GC oven LEL 4% hydrogen in Air
  6. 6. Safety measures Monitor hydrogen usage Safety measures in GC hardware □ Safety Shutdown: when gas pressure set points are not met, the valve and heater are shut off to prevent explosion □ Flow Limiting Frit: if valve fails in open position, inlet frit limits the flow □ Oven ON/OFF Sequence: Fan purges the oven before turning on heater to remove any collected H2 □ Explosion Test: GC designed to contain parts in case of explosion Hydrogensensor in the oven or valve box
  7. 7. Principleof Operation Hydrogen Sensor Catalytic combustion by catalytized resistor or “pellister” Surface of the pellet acts as a catalyst when hot Exothermal oxidation of flammable gases  2 H2 + O2 → 2 H2O(g) + heat Temperature rise results in a change in the electrical resistance
  8. 8. Principle of Measurement Hydrogen Sensor  Compensator pellet is identical but without catalyst  Compensator pellet removes the effect of environmental factors  Measurement circuit: a Wheatstone Bridge8 18 October 2012
  9. 9. Hardware overview for a Hydrogen Sensor for GC applications
  10. 10. Summary Catalytic Pellistor gas specific sensor, linear range of 0-2% H2 (0-50% LEL) Unaffected by humidity, stable output for long periods, more resistant to shocks and vibrations. Expected lifetime: over five years Long term stability drift sensitivity: less than 2mV User defined alarm: optical, acoustic and/or SMS up to 50% LEL
  11. 11. SummaryContinued Instrument readings: provide real time sensor readings with alarm levels, channel states Valve : High pressure 3 way solenoid valve Oven operating temperature: up to 450◦C Multiple Sensors: Max 4 sensors individually controlled Sensor options: temperature, barometer, level, oxygen or hydrogen as a leakdetector.
  12. 12. Contact Lenny Kouwenhoven, Director of R&D, withquestions or to request additional information on theDVLS³ Simply, Smart Sensor for gas chromatographysystems.Email:lenny.kouwenhoven@davinci-ls.comT: +31 (0) 10 258 1870F: +31 (0) 10 258 1879