Industrial Use of Propane Gas Sensors

Propane is widely used in manufacturing, petrochemical, and energy industries as a fuel for technological processes and material handling equipment. At the same time, propane presents a specific safety risk due to its flammable range of approximately 2.1 to 9.5 percent by volume in air and its higher density compared to air, which causes gas to accumulate near the ground in the event of a leak.

In industrial environments, propane leakage creates several critical hazards. Accumulation in low-lying or poorly ventilated areas significantly increases the risk of ignition, while even relatively small leaks can escalate into large fires. At elevated concentrations, propane can also displace oxygen in confined spaces, posing an additional risk to personnel before flammable limits are reached.

For these reasons, propane detection is required in facilities where LPG is stored, transported, or used in technological processes, including LPG storage and distribution sites, chemical and petrochemical plants, metalworking and manufacturing facilities, and refineries. Reliable propane gas detection is a key element of explosion prevention and a mandatory component of industrial safety systems in hazardous areas.

Propane gas sensors continuously measure C₃H₈ concentration in the ambient air and provide signals for alarms, shutdown logic, or ventilation control before hazardous levels are reached. In industrial safety systems, two sensing principles are primarily applied: catalytic (pellistor) and infrared (NDIR). Semiconductor sensors may be used in non-hazardous applications but are generally not considered a core technology for explosion protection.

Catalytic (Pellistor) Sensors

Catalytic sensors detect propane through controlled oxidation on a heated, catalyst-coated element. The heat released during the reaction changes the electrical resistance of the sensing element, which is converted into a gas concentration signal, typically referenced to the Lower Explosive Limit. This technology is well established and widely used in LEL-based safety systems. Its limitations include dependence on oxygen concentration, sensitivity to catalyst poisoning, and the need for regular calibration and periodic replacement.

NDIR (Infrared) Sensors

NDIR sensors measure propane concentration by detecting absorption of infrared radiation at wavelengths characteristic of C₃H₈ molecules. The measurement principle is non-consumptive and does not rely on chemical reactions or oxygen presence. As a result, NDIR sensors provide stable long-term performance with reduced maintenance requirements. Industrial NDIR sensors, such as MIPEX-05, are designed for continuous operation in hazardous areas, offering intrinsic safety, digital interfaces, and extended service life suitable for fixed industrial installations.

Semiconductor (MOS) Sensors

Semiconductor sensors detect propane through changes in the electrical resistance of a sensitive layer exposed to gas. While compact and cost-effective, they are strongly influenced by temperature, humidity, and cross-sensitivity to other gases. For this reason, MOS sensors are typically limited to non-hazardous environments and are not widely used as primary detectors in industrial explosion protection systems.

In industrial hazardous areas, propane gas sensors are integrated into dedicated safety and control systems used for explosion prevention and emergency response. Sensor signals are processed by safety controllers or distributed control systems to initiate predefined protective actions when propane concentration exceeds permissible limits.

Integration typically includes alarm generation, activation of emergency shutdown functions, and interaction with ventilation systems to reduce gas concentration in affected zones. Measurement data is also recorded for operational analysis, incident investigation, and compliance with safety regulations.

Such integration ensures that propane detection is not an isolated function, but a core element of the overall industrial safety architecture, supporting timely decision-making and automatic risk mitigation without reliance on external monitoring platforms.

Regular maintenance is required to ensure reliable propane detection and compliance with industrial safety requirements.

Recommended practices include:

• Calibration, performed at intervals defined by sensor type, operating conditions, and regulatory requirements, typically every 3–6 months.
• Visual inspection of sensor housings and inlets to identify dust accumulation, corrosion, or mechanical damage.
• Functional testing, including bump tests and alarm verification, carried out in accordance with site safety procedures.
• Control of surrounding materials, particularly avoiding silicone-based sealants and compounds near catalytic sensors.

Proper training of operating and maintenance personnel is essential to ensure correct handling of gas detection equipment and to maintain the effectiveness of the overall safety system over its service life.

Propane gas detection equipment used in industrial hazardous areas must comply with international certification schemes governing operation in explosive atmospheres.

ATEX and IECEx define requirements for equipment intended for use in explosive gas environments, including design, testing, and intrinsic safety parameters. The IEC / EN 60079 series specifies technical requirements for electrical equipment used in hazardous areas, covering intrinsic safety, flameproof protection, and associated installation rules. In North America, propane detection equipment is additionally subject to UL and CSA certification frameworks for hazardous location applications.

Propane sensors installed in industrial facilities must be appropriately rated for Zone 1 or Zone 2 environments, depending on the assessed explosion risk, and must be deployed in accordance with local regulations and site-specific safety procedures.

The development of propane gas detection in industrial safety systems is focused on improving measurement stability, reducing maintenance requirements, and simplifying integration into existing protection architectures.

Current trends include:

• Wider adoption of NDIR sensors as a reference technology for continuous propane monitoring in hazardous areas.
• Extended sensor lifetime and reduced calibration frequency, driven by non-consumptive measurement principles.
• Integration of multi-gas capability within industrial safety systems to support combined monitoring of hydrocarbons and related gases.
• Further reduction of power consumption and sensor size, enabling deployment in fixed installations with strict intrinsic safety constraints.

In practice, progress in propane gas detection is achieved through incremental improvements in sensor robustness, intrinsic safety, and long-term reliability, rather than through radical changes in system architecture.

A chemical processing facility in Europe implemented a fixed NDIR-based propane detection system in LPG storage areas and along critical process lines. The system was integrated with the site’s alarm and emergency shutdown infrastructure.

During normal operation, elevated propane concentration was detected near a transfer point. The detection system generated an alarm and initiated automatic isolation of the affected section, allowing operators to eliminate the leak before hazardous concentrations were reached.

The incident was resolved without personnel exposure or production interruption, confirming the effectiveness of continuous NDIR-based propane monitoring as part of an integrated industrial safety system.

Propane is widely used in industrial processes, but uncontrolled leaks present a significant explosion and fire hazard in hazardous areas. Effective risk mitigation depends on continuous gas monitoring and reliable integration of detection systems with alarms, ventilation, and emergency shutdown logic.

Catalytic sensors remain applicable in LEL-based explosion protection systems where regular maintenance is available. NDIR sensors provide stable, long-term propane monitoring with reduced maintenance requirements and are well suited for fixed industrial installations requiring high reliability over the equipment lifecycle.

The selection of propane gas detection technology should be based on hazard classification, environmental conditions, maintenance strategy, and regulatory requirements. Properly designed and maintained detection systems are a fundamental element of industrial safety, supporting the protection of personnel, infrastructure, and uninterrupted operation.