Explosion-Proof Universal Gas Monitor

A combustible gas detector continuously monitors the air for flammable gases like methane, propane, or hydrogen. It alerts you before concentrations reach explosive levels, protecting workers, property, and compliance with fire codes.

Depending on the sensor type, detectors measure gases such as methane, propane, butane, hydrogen, ethylene, and other hydrocarbons.

Combustible gases become dangerous when they mix with air in certain concentrations. These are called explosive limits:

• Lower Explosive Limit (LEL): The lowest concentration of a gas in air that can ignite if exposed to an ignition source. Below the LEL, the mixture is too “lean” to burn.
• Upper Explosive Limit (UEL): The highest concentration of a gas in air that can ignite. Above the UEL, the mixture is too “rich” to burn.

• LEL: Percentage of gas concentration at which ignition becomes possible. Combustible detectors typically measure 0–100% LEL.
• PPM (parts per million): A finer measurement, usually used for toxic gases rather than combustibles.

• Molecular Property Spectrometer (MPS): Multi-gas, long life, low maintenance. MPS sensors use advanced spectroscopy to analyze the molecular properties of gases in real time, distinguishing multiple gases with one sensor and without requiring frequent calibration.

• • Detects multiple flammable gases with one sensor.

• • Long lifespan of 15+ years, with minimal calibration required.

• • Resistant to poisoning or drift.

• • Works across wide temperature and humidity ranges.

• • Applications: Oil & gas, industrial plants, labs, battery charging areas, and environments with unknown or mixed flammable gases.

• • Detection limits: Typically, down to 0–100% LEL.

• • Gases detected: Hydrogen, methane, propane, butane, ethylene, ethane, and more (14+ common hydrocarbons).

• Electrochemical Sensors: Gas molecules react with an electrolyte inside the sensor, producing an electrical signal proportional to gas concentration.

• • High sensitivity and selectivity.

• • Compact and cost-effective.

• • Low power consumption.

• • Limited lifespan (2–3 years).

• • It can be cross-sensitive to other gases.

• • Environmental conditions (humidity, temp) affect performance.

• • Applications: Toxic gas monitoring (CO, H₂S, NO₂, Cl₂, O₂ deficiency/enrichment). Widely used in confined space entry, labs, and industrial facilities.

• • Detection limits: Parts per million (ppm) — varies by gas.

• • Gases detected: Carbon monoxide, hydrogen sulfide, nitrogen dioxide, chlorine, oxygen, ammonia, and other toxic gases.

• Pellistor (Catalytic Bead): Low-cost but requires oxygen and regular calibration. Detects flammable gases by oxidizing them on a heated catalyst bead, causing a temperature change and resistance shift.

• • Proven, low-cost technology.

• • Effective for a wide range of flammable gases.

• • Fast response.

• • Lifespan 2–5 years.

• • Applications: Flammable gas monitoring in oil & gas, refineries, chemical plants, and confined spaces.

• • Detection limits: Typically 0–100% LEL.

• • Gases detected: Methane, propane, butane, hydrogen, and other combustibles.

• Non-Dispersive Infrared (NDIR): Stable and durable, best for methane and CO₂, but cannot detect hydrogen. Infrared light passes through a gas sample; target gases absorb specific wavelengths, allowing concentration measurement.

• • Very stable, long life (5-10 years).

• • Low maintenance, no consumable parts.

• • Highly selective (specific gases absorb specific IR wavelengths).

• • Not effective for gases that don’t absorb IR (e.g., hydrogen).

• • Performance can be affected by dust/moisture.

• • Applications: CO₂ monitoring (greenhouses, breweries, labs, cryogenics), refrigerant leak detection, combustion safety.

• • Detection limits: ppm to % volume, depending on gas.

• • Gases detected: Carbon dioxide, methane, refrigerants, and hydrocarbons that absorb IR.

• Photoionization (PID): Uses UV light to ionize volatile organic compounds (VOCs) and some toxic gases, producing a measurable current.

• • Extremely sensitive (ppb to ppm).

• • Detects a wide range of VOCs.

• • Fast response.

• • Requires frequent maintenance and calibration.

• • Can’t identify specific compounds – measures total VOCs.

• • Humidity can affect readings.

• • Applications: Environmental monitoring, hazmat response, industrial hygiene, and leak detection of solvents and VOCs.

• • Detection limits: Parts per billion (ppb) to parts per million (ppm).

• • Gases detected: Benzene, toluene, xylene, formaldehyde, and thousands of VOCs.

Install detectors near potential leak sources and where gases may accumulate. For lighter-than-air gases (e.g., hydrogen, methane), place sensors high; for heavier gases (e.g., propane, butane), place them near the floor.

In hazardous locations classified by OSHA or NFPA, explosion-proof or intrinsically safe detectors are required. PureAire offers explosion-proof options to meet these safety standards.

Yes. PureAire Combustible Gas Detectors include relay outputs for local alarms, ventilation activation, or connection to fire panels, SCADA, or remote monitoring systems like CloudConnect.

Yes. PureAire engineers its detectors for use under the International Fire Code (IFC) 916, OSHA requirements, and other industry standards. CloudConnect supports compliance with IFC §916.5 by delivering continuous monitoring, logging, and remote alerting.

• MPS: 15+ years.
• Electrochemical: 2-3 years.
• Pellistor: 2–5 years.
• NDIR: 5–10 years.
• PID: 2-5 years.

Calibration is the process of exposing a gas detector to a known concentration of gas to verify and adjust its accuracy. Over time, sensors can drift due to environmental conditions, sensor aging, or contamination. Calibration ensures the monitor continues to give reliable, accurate readings.

• MPS: Rarely requires calibration; designed for long-term stability.
• Electrochemical: Every 6–12 months.
• Pellistor: Every 3–6 months due to poisoning and drift risks.
• NDIR: Usually once a year, sometimes less frequently.
• PID: Often monthly or quarterly, depending on VOC exposure.

Best practice:

• Bump test (a quick exposure to gas to confirm response): Before each use or daily in critical safety applications.
• Full calibration: At the manufacturer’s recommended interval, or sooner if the bump test fails.

Always follow manufacturer recommendations and local safety codes.