Survival of the Toughest: Designing Gas Sensors for Harsh Environments

Conquering Harsh Environments: 4 Challenges Gas Sensors Must Master

For decades, Hydrogen has served as a popular and powerful industrial feedstock. That’s why any sensing device tasked to detect it should be fit to operate under every industrial setting - from the moisture-rich conditions of an electrolyzer to the hazardous Zone 0 areas in oil and gas plants.

Unfortunately, most gas detectors today fail to deliver on these requirements. As a result, premature sensor failure is a widely reported pain point by plant operators. In this article, we analyze the environmental factors that challenge the durability of gas sensors and what it takes to create a gas sensor that never fails

Environmental Factors that Impact Sensing Reliability: What Sets Us Apart

While something of the scale and magnitude of the Fukushima disaster is a rarity, there’s been a spate of explosions involving hydrogen cylinders. Such incidents underscore the importance of a hydrogen monitoring system that is rugged enough to be placed in a high-pressure and high-temperature environment.

Besides heat and pressure, there are many other environmental stresses a gas sensor must overcome to be truly reliable. Let’s take a look at what they are:

1. Exposure to High Concentrations of Hydrogen & other gases

A sensor tasked to provide purity measurement or accurate analysis of hydrogen should be able to handle it at high concentration levels. Sadly, most hydrogen sensors in the market can only handle H2 exposure till the lower explosive limit (LEL) of 4% volume in Air. And they fail almost immediately when installed at the source, where concentrations peak to as high as 100% pure H2. The lack of resilient sensors makes plant operators opt for costly in-line analyzers.

The 21Senses Advantage: Both solid-state electrochemical sensors and MEMS-based nanochip sensors are designed to detect hydrogen and toxic gas leaks in the most hazardous places, such as Class 1 Division 1 areas of an oil and gas plant. The electronics and hardware components in these sensors allow them to monitor and measure hydrogen even at 100% concentration levels.

2. High Humidity

A dependable sensing mechanism for electrolyzer and fuel cell applications should be humidity resistant up to 100% condensation levels. However, sensors based on certain platforms, like metal oxide (MOX) technology, are susceptible to moisture fluctuations and are known to suffer from drift and calibration issues.

The 21Senses Advantage: Our miniaturized sensor design with patented technolgy allows them to operate in moisture-laden environments of electrolyzers and fuel cells. They don’t require constant calibration and maintain sensitivity and selectivity under every condition - from dry to extreme humidity.

Our MEMS nanochip detectors are also equipped with infrared technology to help them measure moisture and calibrate accordingly.

3. Exposure to Dust and Other Gases

IFuel cell-powered industrial forklifts work surrounded by dust and various contaminants. This is not good news for devices like catalytic detectors, where a dust build-up on the inlets is known to trigger a false positive or a false negative.

Some sensors like MOX also show cross-sensitivity to interferents such as carbon monoxide, methane, and other combustible gases. And any H2 monitor with poor selectivity or durability cannot be counted upon in high-risk industrial operations or ensuring passenger safety in hydrogen-powered vehicles, including cars, trains, and buses.

The 21Senses Advantage: We have engineered our sensors with a self-cleansing principle that does not allow chemicals or vaports to get in the way of operations. They contain a smart mechanical components that prevents contaminants from entering the electronics.

Our solid-state detectors are highly selective to hydrogen with zero cross-sensitivity to other combustible and reducing gases. Meanwhile, our MEMS sensor can be programmed to accurately detect various target gases (including H2) in binary mixtures.

4. Extreme Temperatures

In-situ monitoring is the most effective way to catch early leaks or purity variations. And a gas sensor should be able to endure extreme temperatures with as much stability and responsiveness as in ambient conditions.

We’re talking about temperatures ranging from as low as -40°C in the case of fuel cell-powered vehicles operating in northern climates to as high as 100°C and even more in gas turbines and nuclear power plants. Unfortunately, most hydrogen gas leak detectors break down almost instantly when placed in such conditions.

The 21Senses Advantage: Our MEMS-based nanochip sensors, thanks to a silicon carbide wafer construction, can withstand in-process temperatures up to 300°C with remarkable ease. Our solid-state electrochemical sensors aren’t far behind, boasting a rugged IP 68 aluminum enclosure that allows them to endure up to 65°C, with ongoing efforts to take their endurance up to 100-120°C.

These detectors can help avoid complex engineering efforts and various risks associated with sampling methods for H2 measurement.

Building a Sensing Solution That Thrives Under All Conditions.

As the world turns to hydrogen to decarbonize industries, technologies that monitor it must be designed to survive and thrive in the most challenging settings. A typical industrial environment is characterized by extreme heat, dust, moisture, and pressure.

And the list of stress factors doesn’t stop there. Virtually every application brings a unique set of challenges that a sensor must overcome - like vibrations and shocks in the case of hydrogen-powered vehicles.

At 21Senses, we build sensors for wide-ranging applications. So, the device that detects hydrogen leaks in an industrial forklift operating in sub-zero climates can also measure the purity levels of H2 inside the extreme heat and moisture-rich environment of an electrolyzer. Reach out to us today to learn more about our fail-safe sensing solutions.

Sources:

. Hydrogen Leakage Sensing and Control: (Review)

. Trends in gas sensor development for hydrogen safety.

. Which pressure sensor is suitable forhydrogen?

. Hydrogen Pressure Sensors - Industrial & Hazardous.

. Summary and Findings from the NREL/DOE Hydrogen Sensor Workshop (June 8, 2011)

. Design study of hydrogen monitoring equipment for severe accident in containment of nuclear power plant

5. Varying Pressure Levels (for future)

With the growing demand for H2 in power generation and the automobile industry comes the need to transport it safely. This is usually done through tanks and pipes, where pressure is incredibly high, much more than what you’d find in natural gas lines. In such high-pressure zones, monitoring devices with thin membranes may experience hydrogen permeation and embrittlement, leading to sensing failure.

The 21Senses Advantage: Our solid-state electrochemical sensor is designed to measure the direct partial pressure of hydrogen in any gas mixture. These devices can handle significant pressure fluctuations and can be easily calibrated to local pressure levels, from vacuum to 1.5 bar.