In today’s era of rapid industrialization and new energy development, hydrogen is widely used as a clean energy source. However, its flammable and explosive nature also poses significant safety challenges. As a professional enterprise with more than 40 years of experience in gas sensing technology, Nexisense has accumulated extensive expertise in the field of catalytic combustion sensors. This article starts from the core structure and systematically analyzes the internal construction, operating mechanism, technical advantages, and application scenarios of this highly reliable sensor, helping readers fully understand its critical role in hydrogen monitoring. Through this analysis, you will gain a clearer understanding of how to select and apply such sensors to ensure safety in production and laboratory environments.

Basic Working Principle of Catalytic Combustion Hydrogen Sensors

The working basis of a catalytic combustion hydrogen sensor lies in the catalytic reaction between hydrogen and oxygen. This type of sensor uses precious metal catalysts to promote the oxidation and combustion of hydrogen at low temperatures, generating heat that causes resistance changes, which are then converted into electrical signal outputs. Compared with other sensor types, such as electrochemical or infrared sensors, it performs particularly well in detecting combustible gases and is especially suitable for hydrogen, which can ignite even at low concentrations.

The core of the principle is the oxidation reaction: when hydrogen comes into contact with the heated catalyst surface, it reacts with oxygen in the air and releases heat. This heat raises the temperature of the sensing element, thereby changing its resistance value. Through precise circuit design, this change is amplified and output as a quantifiable signal. Nexisense optimizes this principle to ensure stable operation even in complex environments, avoiding false alarms or missed detections.

Detailed Explanation of Core Structural Components

The structure of a catalytic combustion hydrogen sensor is compact and sophisticated. It mainly consists of sensing elements, sensor carrier, explosion-proof structure, and housing with pins. These components work closely together to form an efficient and safe detection system.

Sensing Elements: The Core of Detection and Compensation

The sensing element is the “heart” of the sensor and is divided into a detection element (D element) and a compensation element (C element). The detection element consists of a platinum wire coil carrier coated with a catalyst layer. The catalyst usually adopts precious metal nanomaterials such as palladium (Pd) and platinum (Pt). When exposed to hydrogen, these materials trigger catalytic combustion reactions, generating heat and causing changes in the resistance of the platinum wire, thereby reflecting hydrogen concentration.

The compensation element has a similar structure, but its surface is covered with an inert coating or treated with passivation. It does not participate in catalytic reactions and is only used to compensate for environmental factors such as temperature and humidity, ensuring detection accuracy. The two elements are typically arranged in a symmetrical Wheatstone bridge design. This classic circuit effectively eliminates non-specific interference and improves signal purity.

Nexisense offers a wide range of models in this category, including ZC25D, ZC25B-1, ZC25/ZC25C, ZC28/ZC28C, ZC2529, ZC2528-I, ZC2521-A, ZC25C-1, and ZC25A. These models optimize sensitivity and durability for different application scenarios.

Sensor Carrier Structure: The Key to Support and Heat Transfer

The carrier structure includes the platinum wire coil and ceramic substrate. The platinum wire coil is made of high-purity platinum wire with a diameter typically between 20–50 μm. It serves both as a heating element to provide the temperature required for catalytic reactions and as a resistance temperature sensor to monitor thermal changes in real time. This dual-function design simplifies the structure and improves response speed.

The ceramic substrate is commonly made of 96% or 99% alumina, offering high thermal conductivity, excellent insulation, and strong thermal stability. It not only supports the platinum wire coil but also ensures uniform temperature distribution, preventing local overheating and potential failure. Nexisense emphasizes high-temperature resistance and corrosion resistance in carrier material selection to ensure long-term operation in harsh environments.

Explosion-Proof Structure Design: A Barrier for Safety Assurance

In hydrogen detection, explosion protection is a top priority. Nexisense sensor explosion-proof flame arresters are sintered from stainless steel or copper alloy, with pore diameters precisely controlled at ≤100 μm. This micro-porous structure prevents external explosions from propagating while limiting internal combustion, ensuring that even in explosive environments, chain reactions will not occur.

This design complies with international explosion-proof standards such as ATEX and IECEx, making it suitable for high-risk locations like petrochemical plants and mines. The micro-pores allow gas diffusion into the sensor while blocking flame propagation, achieving a balance between safety and sensitivity.

Housing and Pins: Interfaces for Integration and Connection

The housing is typically made of engineering plastics such as PPS or PBT, or metal materials, providing mechanical protection and environmental adaptability. Pin configurations usually include standard 4-pin or 6-pin designs. Two heating pins supply power to the platinum wire coil, while the remaining signal pins output the bridge signal. This modular design facilitates integration into various systems and supports quick installation and maintenance.

Cooperative Working Mechanism of All Components

The sensor’s efficiency stems from the cooperation among its components. The detection element catalyzes hydrogen combustion and generates heat, with platinum wire resistance changes proportional to hydrogen concentration, enabling precise quantification. The compensation element continuously corrects environmental interference, improving zero stability and anti-interference capability.

The explosion-proof housing ensures safety compliance with international standards. The ceramic substrate provides support and heat conduction, ensuring uniform temperature distribution and preventing errors caused by thermal gradients. Overall, the mechanism resembles a precision instrument in which all parts complement each other, forming a closed-loop detection system. In actual operation, when hydrogen enters the sensor, reaction heat increases the detection element resistance, unbalancing the bridge and outputting a signal that triggers alarms or control actions.

By optimizing these mechanisms, Nexisense enhances sensor response time and reliability. For example, a response time of ≤15 s (T90) ensures timely warnings in emergency situations.

Nexisense Technical Advantages

Nexisense’s advantages in the field of catalytic combustion sensors are evident. First, precise catalyst formulation optimizes the palladium–platinum ratio, improving sensitivity and selectivity while reducing cross-interference from other gases. Second, advanced packaging processes such as laser welding ensure airtightness and mechanical strength, extending service life.

In addition, strict quality control measures—including 100% aging tests and temperature cycling tests—ensure that every product delivered is reliable. Nexisense also provides customized services, adjusting range, sensitivity, or form factor according to customer needs to meet diverse applications.

Typical Technical Parameters

Typical parameters of Nexisense hydrogen sensors include a detection range of 0–100% LEL, sensitivity of 55–65 mV/%LEL (under 1% LEL hydrogen conditions), and response time ≤15 s (T90). Operating voltage is 2.5–3.3 V constant voltage supply, with operating current of 120–150 mA. These parameters are tested under standard environmental conditions to ensure stable performance in practical applications.

Expanded Application Scenarios

Catalytic combustion hydrogen sensors are widely used in industrial hydrogen leak detection, such as chemical plants and refineries, providing real-time monitoring of pipelines and storage tanks to prevent accidents. In fuel cell system safety monitoring, they ensure the stability of the hydrogen supply chain and prevent leaks from affecting fuel cell performance.

Laboratory hydrogen safety is another important field, where sensors are integrated into ventilation systems to provide instant alarms. Emerging new energy fields, such as hydrogen fuel vehicles and hydrogen power stations, also rely on these sensors for hydrogen monitoring, promoting the transition to green energy.

For example, in a typical industrial scenario, sensors are installed on hydrogen production lines. When concentration exceeds a threshold, the system automatically cuts off gas supply to protect personnel safety. Nexisense products have proven their value in multiple projects, helping enterprises enhance safety management.

FAQ: Frequently Asked Questions

1. What is the working principle of a catalytic combustion hydrogen sensor? It detects hydrogen concentration by using precious metal catalysts to promote hydrogen oxidation and combustion, generating heat that changes resistance values.

2. What advantages does it have compared with electrochemical sensors? Catalytic combustion sensors respond faster, are suitable for high-concentration detection, and have longer lifespans, but require heating.

3. How does the explosion-proof design ensure safety? By using micro-porous flame arresters to limit flame propagation and comply with ATEX and IECEx standards.

4. Can Nexisense sensors detect other gases? They are mainly designed for hydrogen but can be extended to other combustible gases such as methane by adjusting the catalyst.

5. What does a response time ≤15 s mean? It indicates the time required to reach 90% of the output signal after gas exposure, ensuring timely warnings.

6. How should these sensors be maintained? Perform regular calibration, avoid exposure to toxic gases, and check pin connections.

7. What ambient temperatures are suitable? Typically from −40°C to +80°C, depending on the specific model.

8. What does customization include? Adjustment of range, sensitivity, form factor, and interfaces to meet specific requirements.

9. What is the typical sensor lifespan? Generally 3–5 years under normal usage, depending on environment and maintenance.

10. How are they integrated into existing systems? Through standard pins and signal outputs, compatible with PLCs or IoT platforms.

Conclusion

With its reliable structure and efficient mechanism, the catalytic combustion hydrogen sensor has become a trusted choice for hydrogen safety monitoring. Leveraging deep technical expertise, Nexisense provides comprehensive solutions from core components to application support. In the hydrogen energy era, this technology not only safeguards safety but also supports sustainable development. Choosing the right sensor is the first step toward efficient monitoring.