Reactor Gas Detector: Core Safety Barrier for Chemical Production Leak Prevention

In fine chemicals, pharmaceutical intermediates, pesticides, and new materials industries, reactors are the core equipment for material transformation, synthesis, and polymerization. The process often involves high temperature, high pressure, corrosive media, and flammable/toxic gases such as hydrogen, ammonia, benzene, chlorine, and hydrogen sulfide. Seal failure, flange leakage, agitator shaft seal damage, or pipeline rupture can rapidly release gases, forming explosive mixtures or high-concentration toxic zones, causing fires, explosions, or poisoning.

Recent accidents caused by reactor leaks highlight the need for online gas monitoring to ensure intrinsic safety and prevent major risks. The Nexisense SGA-500 series, with industrial-grade explosion-proof design and imported high-performance sensors, provides reliable, precise, and rapid protection for reactor safety.

Main Risks and Hazards of Reactor Gas Leaks

• Flammable and explosive gases: H₂, CH₄, C₂H₄, CO, with low explosion limits (H₂ only 4% VOL), ignitable by sparks or static electricity.

• Highly toxic gases: NH₃, Cl₂, H₂S, HCN, lethal even at small doses.

• Carcinogenic/toxic organics: Benzene, toluene, vinyl chloride, acrylonitrile, with long-term neurotoxic and hematological effects.

• Corrosive gases: HCl, HF, damaging equipment and human health.

According to GB 18218-2018 and GBZ 2.1-2019, allowable concentrations are extremely low (e.g., benzene 6 mg/m³, H₂S 10 mg/m³). Reactor areas often fall under explosion hazard zones 1/2, with fast leak dispersion, making traditional inspections insufficient for early detection.

Why Reactors Require Dedicated Online Gas Detection

Portable instruments are suitable for emergency checks, but continuous reactor production and confined, hazardous environments require fixed online monitoring to achieve:

• 24/7 real-time monitoring

• Second-level response with immediate alarms

• Automatic linkage to ventilation, shut-off, or sprinklers

• Remote data transmission for centralized management and historical tracking

The SGA-500 series is optimized for reactor scenarios with explosion-proof, corrosion-resistant, fast-response, and anti-interference features, suitable for high-temperature, high-humidity, acidic, and alkaline environments.

Core Advantages of Nexisense SGA-500 Reactor Gas Detectors

• Multi-gas compatibility: H₂, NH₃, C₆H₆, Cl₂, H₂S, CO, VOCs, covering nearly all common reactor media

• Flexible range: 0–100 ppm / 0–1000 ppm / 0–50% LEL

• Fast response: T90 ≤ 45s

• Explosion-proof: Ex d IIC T6 Gb, suitable for zones 1/2

• Output interfaces: 4–20mA, RS485 Modbus RTU, seamless PLC/DCS integration

• Protection: IP65/IP66, corrosion-resistant housing (316L stainless steel or special coating)

• Local display and alarm: LCD showing real-time concentration and trend curves, ≥85dB audible alarm

Modular design facilitates sensor replacement and reduces maintenance costs.

Scientific Installation and Strategy for Reactor Gas Detectors

• Near potential leak points: reactor top manhole, flange connections, agitator shaft seal, bottom discharge valve, inlet/outlet pipe joints

• Consider gas density:

• Lighter than air (H₂, NH₃): install above leak source

• Heavier than air (benzene, Cl₂, H₂S): install 0.3–1.0 m above floor or near ground

• Quantity: medium reactors 2–4 points; large or clustered reactors 6–10 points for a 3D monitoring network

• Avoid interference: away from steam vents, exhaust, strong vibration zones

CFD simulation or smoke testing is recommended before installation. Nexisense can provide on-site survey and design services.

Building a Complete Reactor Gas Leak Alarm and Emergency Linkage System

• Integrate with SGA-800 alarm controller

• Multi-channel access and centralized display

• Tiered alarms: warning + mandatory

• Automatic linkage: local exhaust, pump shut-off, water spray, heating medium cut-off

• Data platform integration: cloud upload, mobile app monitoring, SMS alerts

Typical emergency chain: detector senses leak → local alarm → controller triggers linkage → personnel use PPE → incident recorded for analysis.

Installation, Commissioning, and Maintenance

• Explosion-proof cables and sealed joints; comply with electrical safety standards

• Zero/span calibration before commissioning using certified gas

• Alarm points set according to risk assessment (usually 30–50% of limit)

• Monthly inspection of probe cleanliness and corrosion

• Quarterly calibration or per internal control

• Sensor lifespan 2–3 years; replace if drift or slow response occurs

• Avoid direct water wash; use neutral cleaners

  
  

FAQ

1. Priority gases: H₂, NH₃, benzene, Cl₂; configure appropriate sensors per process media.

2. Gas installation height: light gases above, heavy gases below; combine CFD for multi-point 3D layout.

3. Explosion-proof certification: Ex d IIC T6 Gb, suitable for zones 1/2; 316L stainless steel housing resists corrosion.

4. High-temperature stability: wide temperature range (-40°C–+70°C); use cooling sampling tube or insulation if necessary.

5. DCS/SIS integration: via 4–20mA or RS485 Modbus RTU to drive valves, fans, or safety interlocks.

6. False alarms: caused by cross-interference, dust, condensation, expired calibration; prevent with selective sensors, filters, regular calibration, optimal placement.

7. Detection coverage: 5–10 m radius; large or multiple reactors require distributed detectors for grid monitoring.

8. Data usage: storage, trend export, alarm logs for risk assessment, hazard correction, emergency drills, and compliance reporting.

Conclusion

Reactors are the heart of chemical production; gas leaks directly affect safety. Nexisense SGA-500 series offers reliability, rapid response, and explosion-proof durability, creating a robust safety barrier. Installing professional monitoring equipment is not just passive defense, but an essential measure for corporate responsibility and high-quality development.

For reactor gas monitoring upgrades or solution selection, Nexisense provides practical and precise protective solutions tailored to specific processes.