Gas Detection Solutions for Gas Stations and Refueling Stations: Nexisense SGA-500 Application

In the petrochemical field, gas stations and refueling stations are key nodes in the energy supply chain, storing large quantities of gasoline, diesel, liquefied natural gas (LNG), or compressed natural gas (CNG), all highly flammable and explosive. Combustible gases such as methane, propane, butane, or gasoline vapors can accumulate and ignite through open flames, sparks, or static electricity, posing threats to personnel, property, and the environment. With strict enforcement of GB 50160 (Fire Protection Design Code for Petrochemical Enterprises) and GB 18218 (Major Hazard Source Identification for Dangerous Chemicals), real-time online gas monitoring has become a core element of site safety management. Monitoring low concentrations of volatile gases requires high-sensitivity devices to detect minor leaks and prevent escalation.

The Nexisense SGA-500 series online gas concentration detectors are optimized for oil and gas station environments. They use imported catalytic combustion or infrared sensors, professionally calibrated and secondarily developed, achieving ±5%FS accuracy and T90 response time under 15 seconds. Full-range temperature and humidity compensation and signal amplification ensure stable operation from -20°C to +50°C and 0-95%RH. Industrial-grade intrinsic safety design with Ex d IIC T6 Gb explosion-proof certification suits Zone 1 and 2 hazardous areas. The devices are plug-and-play, automatically triggering alarms and relay outputs to fans, solenoid valves, or sprinklers when thresholds are exceeded. Combined with the SGA-800 alarm controller, multi-point power supply, zoned management, and remote notifications are supported. This article provides risk analysis, selection guidance, integration tips, and practical cases for petrochemical enterprises and engineering contractors.

Gas Risks and Monitoring Requirements in Gas and Refueling Stations

Gas risks concentrate in storage tank areas, pump islands, unloading points, and pipeline connections. Gasoline/diesel vapors form combustible mixtures with lower explosive limits (LEL) as low as 1-7%VOL, influenced by temperature and wind. LNG/CNG leaks form low-temperature clouds that can ignite. Low-concentration VOCs like benzene and toluene do not explode immediately but exceed OSHA PEL thresholds (benzene 1ppm) and harm health and the environment over time.

Monitoring demands real-time and zonal coverage. SGA-500 series can be installed near tank breathing valves or under pump islands, monitoring 0-100%LEL combustible gases and 0-2000ppm VOCs. Controllers ensure immediate isolation of the source upon leakage, with response delays under 5 seconds.

In a Southern China gas station chain, SGA-500 combustible modules integrated via RS485 to SCADA automatically cut pumps and activate sprinklers during exceedances, reducing leak incidents by 65% and ensuring compliance with GB 3836 Explosion-Proof Electrical Equipment standards.

Detector Selection Guide: Matching Oil and Gas Environments

Selection considers gas type, installation location, explosion-proof rating, and budget. Combustible gases prioritize catalytic combustion sensors (0-100%LEL, resolution 0.1%LEL) suitable for gasoline vapors. VOC low-concentration monitoring uses PID photoionization (0-2000ppm, response <3s), offering high sensitivity for early leak detection.

Environmental adaptation: tank areas require Ex d housings and IP65 protection; pump islands use sampling pumps with dust filters. SGA-500 is NIST-traceably calibrated, zero drift <±1%FS/month, lifespan 2-5 years.

Budget considerations: basic models suit small stations, advanced models support LoRa wireless expansion for large refueling stations. ROI analysis shows preventing a single leak can save hundreds of thousands, with payback in 12-18 months.

System Integration Considerations: Ensuring Reliable Linkage

Integration amplifies practical value. SGA-500 supports 4-20mA (load <500Ω), Modbus RTU (9600bps), RS-485, enabling connection to Honeywell or Siemens SCADA. SGA-800 controller unifies up to 32 points, allowing zoned alarms and remote notifications.

Linkage configuration: dry contact relays (30VDC/2A) drive solenoid valves, fans, or audible/visual alarms. Dual-level thresholds + 5%FS hysteresis prevent false alarms. Power supply 24VDC (ripple <100mV), PoE optional. AWG22 shielded cable <1200m with surge protection.

Software supports bulk parameter deployment and OPC UA trend export. RESTful API pushes data to MES for predictive maintenance. FAT/SAT includes EMC and long-term stability tests, uptime >99.5%. Integration cycles typically 10-15 days.

OEM Customization and Bulk Supply Advantages

Nexisense offers flexible B2B OEM services. Sensor modules can embed into client control cabinets, supporting protocol extensions (Profibus DP, EtherNet/IP), custom threshold logic, MOQ 50 units, delivery 4 weeks. Parameterization includes range adjustment and housing upgrades. Bulk orders >500 units enjoy tiered pricing with stable annual production and full ATEX/IECEx certification.

Example: a Middle Eastern oil company customized VOC+combustible dual-channel detectors integrated into station PLCs, winning bids for large refueling station upgrades.

Project Case Studies

Guangdong chain: SGA-500 combustible monitoring at tank area, linked to Rockwell PLC, automatic valve cut-off and sprinkler activation. Zero leak incidents, 100% audit pass rate.

Beijing refueling station pump island: SGA-500 PID VOC module + SGA-800 controller, zonal management, peak control within thresholds, zero health complaints.

Shanghai refining terminal: distributed multi-station deployment, MES trend analysis predicted leaks, reducing failure rate by 22%.

FAQs

1. Which gases does SGA-500 monitor at gas/refueling stations?
Core coverage includes combustible gases (methane, propane, butane, gasoline vapors, 0-100%LEL, catalytic combustion or infrared) and VOCs (benzene, toluene, ethylbenzene, 0-2000ppm, PID). Single or composite configuration depends on station type: gasoline/diesel stations focus on combustible + benzene VOCs; LNG/CNG stations prioritize methane + low-concentration VOCs. All sensors are factory cross-tested, with interference coefficients for software compensation, ensuring accuracy in complex mixed gas environments.

2. How to determine detector quantity and sampling method?
Tank breathing valves and unloading points: single/double diffusion points. Pump islands, nozzle areas, or pipe joints: pump sampling (≤10m tubing) to avoid wind blind spots. LNG cold areas: anti-condensation sampling heads. CFD simulations using 3D models and wind data help optimize placement: typically 3-5 points in tanks, 1-2 per pump island. Response time <10s, reducing explosion risk.

3. How do sensors remain stable in high-humidity, explosive, electrostatic environments?
SGA-500 uses polynomial temperature/humidity compensation (-20°C to +50°C, 0-95%RH), zero drift <±1%FS/month, range drift <±2%FS/year. Probe uses 316L stainless steel + PTFE filter, Ex d IIC T6 Gb, IEC 60079-0 static protection. Quarterly calibration recommended. Catalytic sensors lifespan 2-5 years, PID 1-3 years. Health diagnostics monitor drift, triggering preemptive replacement alerts.

4. OEM minimum order, lead time, and customization?
MOQ 50 units; options: cabinet embedding, logo printing, protocol extension, threshold presets, display adjustments. Standard parameter customization: 4 weeks; firmware/housing changes: 6-8 weeks. NDA and prototype verification provided.

5. How to reduce cross-interference and false alarms?
Catalytic sensors use selective catalysts and filters (<5% interference); PID uses UV lamp and filters (<8%). Cross-tested with multi-component gases, interference reports provided. High/low dual alarm + 5%FS hysteresis, combined with SGA-800 zonal management, keeps false alarms <1/month.

6. How to integrate SGA-500 with SCADA/PLC?
Steps: ① Protocol mapping; ② Communication testing; ③ Linkage debugging; ④ FAT/SAT testing. Key points: isolated RS-485 converters, repeaters for >800m, surge protection >10kA. OPC UA server and Ignition/WinCC templates available. Integration 1-2 weeks.

7. Bulk procurement certification, pricing, logistics?
Each unit includes ATEX/IECEx, CNEx, CE/RoHS, NIST traceable calibration. Bulk ≥500 units: tiered discounts. FOB Shenzhen, EXW/DDP optional. Shipping: sea 30-45 days, air 7-10 days. Serial number and packing list provided for customs and asset tracking. Localization >80% ensures stable delivery.

8. Maintenance, sensor lifespan, predictive maintenance?
First month: monthly zero/range calibration; then quarterly. Lifespan: catalytic 2-5 years, PID 1-3 years. Health diagnostics monitor baseline drift and sensitivity, alerting below 80%, supporting preemptive replacements, reducing unplanned maintenance ~40%.

Summary

The Nexisense SGA-500 series focuses on precision, explosion-proof design, and linkage control, offering end-to-end solutions for monitoring and prevention at gas and refueling stations. It mitigates leak hazards, ensures operational continuity, and supports compliance. Future edge AI integration will enhance predictive capabilities. Petrochemical enterprises and engineering teams are encouraged to share layouts and media types for POC and integrated solutions.