Gas Monitoring Sensors: An Inside Look at CO High and H2 Sensors for the Ventis Pro5

The Ventis Pro5 is recently added two new electrochemical sensors to its portfolio — the hydrogen (H2) sensor and the carbon monoxide high measuring range (CO High) sensor.

To better understand the excitement, a little refresher course on electrochemical sensor technology might help:

Electrochemical Sensors

At their core: electrochemical sensors feature a special electrode in a solution where the target gas reacts, creating a flow of electrons. This flow of electrons generates a current that can be measured, and the strength of this current indicates how much of the gas is present.

Contrary to popular belief, these sensors don’t have a set expiration date. Their lifespan depends on various elements, including the target gas. For example, the life of a CO sensor mainly depends on how much gas it reacts with and at what frequency. A CO sensor that is frequently working beyond its measuring range will fail calibration much faster than a CO sensor that only gets hit with the occasional gas in small concentrations.

CO High Sensors in Action

Up until now, the Ventis Pro5 offered various options for CO detection which could read up to 2000ppm. However, there are industries that can produce extremely high quantities of CO well above that range. They include steel manufacturing, particularly in blast furnaces; petroleum refining during catalytic cracking and reforming; and chemical production of substances like methanol and formaldehyde; coke ovens in the production of coke from coal; pulp and paper mills using black liquor recovery boilers; and combustion-based power plants using coal or biomass fuels.

With the introduction of the CO High sensor, the Ventis Pro5 can now detect CO up to 9,999 ppm in concentration, thus protecting the sensor from burning out prematurely.

Combating Cross Interference

With electrochemical technology, every sensor is designed to react to a specific gas. However, other gases can sometimes trigger a reaction with the sensor’s electrode, causing a reading on the sensor. This is called “cross interference.”

Regular CO sensors can experience cross interference with H2, which can trigger a reading on the CO monitor equal to 22% of the concentration of H2. Because of this, Industrial Scientific offers a CO sensor with low H2 interference (CO/H2 low), which ranges from 0 to 1000ppm. However, this sensor will still show a CO reading equal to 3% of the concentration of H2. If H2 is present in low amounts, this cross-sensitivity is negligible; however, if industries produce H2 in large amounts, the CO sensor could go into false alarm due to the higher concentrations of H2 present.

H2 Sensors in Action

Due to the potential of cross interference in applications where the risk of having both CO and H2 present, the Ventis Pro5 should be configured with a CO/H2 low sensor, as well as an H2 sensor to help identify if CO readings are true or false.

chemical-plant-monitoring-workerIndustries that involve both CO and H2 include petroleum refining, where processes like hydrocracking and desulfurization utilize hydrogen and generate CO as a byproduct; chemical manufacturing, particularly in methanol and ammonia production; steel manufacturing, where traditional blast furnaces produce CO and newer, greener methods increasingly use H2; coke ovens, which generate both CO and H2; and in the production of synthesis gas (syngas), which is a mix of CO and H2 and used in creating a variety of chemicals and fuels.

Other industries that can benefit from a H2 sensor include electrolysis plants, which split water into H2 and O2 using electrolysis; renewable energy; and advanced nuclear power plants, which can product H2 via high temperature electrolysis of thermochemical processes.

Additionally, an H2 electrochemical sensor will measure gas in ppm, up to 2,000ppm. This allows for H2 detection in small concentrations, well below its lower explosive limit (LEL), which is 4%Vol, or 40,000ppm.

For applications where H2 would need to be detected up to its LEL, a catalytic diffusion sensor is perfect for the job. In the Ventis Pro5, pairing an H2 sensor with the LEL will allow the monitor to not only identify the presence of H2 in small quantities, but also notify users when the concentration of H2 has reached a level so high that the environment is at risk of combustion.