According to Mamms Consulting, catalytic combustion (also known as catalytic bead) sensors have been known as "canary in coal mines" for nearly 100 years (in the 17th century, mine workers relied on gold) The canary acts as an alarm system to prevent harmful gases and pollutants from underground. This sensor can be used to alert workers in potentially explosive environments, especially in the mining, natural gas and petroleum industries, to the danger warning line for flammable gases. In the 1960s, scientists introduced nondispersive infrared detectors (NDIRs). While both types of sensors make potentially hazardous work environments safer and are improving every year, recent breakthroughs in flammable gas sensor technology have been achieved.

Catalytic combustion sensor

One of the reasons that catalytic combustion sensors have been used to date is that it can detect almost all flammable gases. Even today, catalytic combustion sensors still account for 60% of the market. Why is there such a strong possession? Because in most cases, catalytic combustion sensors are very reliable if properly maintained.

¡°The catalytic combustion sensor senses any flammable gas and is relatively inexpensive,¡± said Dr. Peter Hsi, co-founder and sensor technologist at RAE Systems. However, catalytic combustion sensors also have some disadvantages, the most important of which is that they are easily poisoned. ¡°This type of sensor is susceptible to catalyst poisoning by silicon, sulfur and other compounds, which shortens its useful life,¡± explains Dr. Hsi, based in San Jose, California.
Even in environments with low levels of silicon, lead or phosphate, the sensor is at risk of degradation and ultimately cannot accurately detect the presence of gas. In the case of a high concentration of combustible gas, the catalytic combustion sensor will be quickly destroyed and stopped. More importantly, catalytic combustion sensors are not able to operate in a low oxygen environment, including in a limited, narrow space. The only way to see if a catalytic combustion sensor is not working properly is through testing, and without a rigorous routine testing process, personnel safety can be compromised.

Figure 1: Catalytic combustion sensors are inexpensive but have high operating power

Other challenges currently facing catalytic combustion sensors include the need to set parameters to accurately measure a particular gas, and the inability to accurately measure a mixture of combustible gases. Due to the relatively high power consumption of catalytic combustion sensors, at least 70 to 100 mA, portable detectors using catalytic combustion sensors are also limited by battery life.

Non-dispersive infrared (NDIR) sensor

Like catalytic combustion sensors, NDIR sensors have played an important role in operating environment safety and gas detection in recent decades. The NDIR sensor is another reliable choice when catalytic combustion sensors are not suitable for use. Unlike catalytic combustion sensors, NDIR sensors do not require frequent recalibration and they are not susceptible to poisoning.
¡°They last longer than catalytic combustion sensors, usually one to two years, up to three to five years,¡± Dr. Hsi said. Since the NDIR sensor can also detect gases in a low-oxygen environment, it is more effective when the catalytic combustion sensor is ineffective. They consume much less power than catalytic combustion sensors and are not damaged even when exposed to concentrated gases.

Figure 2: NDIR sensor can detect a single gas

One of the challenges of NDIR sensors is their inability to detect hydrogen, which is an important and potentially hazardous gas in many mining, natural gas and petroleum environments. Since the NDIR sensor can be adjusted to accurately detect only a single gas, they may not be effective in a mixed gas environment. Finally, because the technology required for NDIR sensors is complex and proprietary, it also results in high operating costs.

Latest technology to improve traditional products
The latest research addresses some of the problems inherent in catalytic combustion sensors and NDIR sensors, and combines the best features of both. For example, NevadaNano's newly designed sensor measures the concentration of flammable gas mixtures and separates the detected gases and mixtures into hydrogen, methane or light/medium/heavy gases. ¡°The MPS combustible gas sensor can identify which flammable gas is present,¡± Dr. Hsi said. ¡°It's smaller and cheaper.¡±
¡°We developed the MPS combustible gas sensor to address the limitations of catalytic combustion and NDIR combustible gas sensors,¡± said Mark Brandemuehl, vice president of marketing and marketing at NevadaNano. With a single calibration, the new MPS combustible gas sensor accurately measures 12 gases and has been able to provide consistent and reliable results for many years. The sensor can also be installed in fixed and portable applications.

Figure 3: Nevada Nano's MPS sensor uses a single calibration to detect and classify multiple explosive gases

¡°The key role of flammable gas sensors is to reliably alert workers when the level of a single gas or mixture of gases becomes unsafe,¡± Brandemuehl said. ¡°We believe that the functionality and reliability of MPS flammable gas sensors can be Workers work safely set new standards."