Introduction

Combustible gas leaks in oil refineries can escalate quickly into fire, explosion, or long-term compliance failures. Choosing the right gas detector is not just a safety decision—it’s a daily operational safeguard.

Yet for many engineering and procurement teams, selecting the appropriate gas detector remains a challenge. With dozens of models, protocols, certifications, and options, it’s easy to get lost in details or delay a purchase entirely.

This guide helps you cut through the noise and make a confident, informed choice—based on real needs, not guesswork.

Common Questions and Concerns

Before making a purchase, most refinery engineers or safety managers ask some variation of the following:

• Which gases should we monitor?

• What detector types are required by law?

• Is a single-gas detector enough, or do we need a multi-gas system?

• What’s the difference between LEL and VOC detection?

• How much do we need to spend to meet compliance—and not overspend?

• How often will this require maintenance?

• What kind of integration do we need with existing systems?

Let’s tackle these questions one by one.

1. What Gases Are Typically Monitored?

In oil refineries, combustible gas detection usually focuses on hydrocarbon vapors, especially:

• Methane (CH₄)

• Propane, Butane, Pentane

• Hydrogen (H₂)

• General volatile organic compounds (VOCs)

Because most refinery environments involve gas mixtures, detectors commonly measure %LEL (Lower Explosive Limit) rather than specific compounds. This simplifies response: when a detector reaches 10% or 20% LEL, it triggers an alarm or shutdown, regardless of the specific gas.

In most cases, LEL-based detectors are sufficient for combustible gas monitoring.

2. Do You Need a Single-Gas or Multi-Gas Detector?

When a single-gas detector is enough:

• The zone only involves flammable gas risk, such as a crude tank area or pipeline corridor.

• The site already has toxic gas and O₂ sensors deployed separately.

• You’re installing multiple detectors across a large area and want to minimize per-unit cost.

When a multi-gas detector is better:

• You need to monitor LEL + H₂S + CO + O₂ in the same area.

• Space is limited, or you want to reduce wiring and maintenance complexity.

• You’re building a modern safety system integrated into SCADA or DCS.

If your site includes confined spaces, catalytic units, or waste handling, a multi-gas detector is typically the more robust and future-ready solution.

3. Key Features You Should Consider

The following are the essential parameters that should guide your decision:

Choosing a gas detector is a lot like choosing a pressure transmitter in a refinery—you wouldn’t just ask for “something that measures pressure.” You’d consider the range, the process medium, the communication protocol, and whether it’s rated for hazardous zones.

The same applies here: the right gas detector should match your actual application—not just in price, but in performance, integration, and long-term reliability.

Gas detectors follow the same logic: more advanced specs deliver more reliable protection over time.

4. Integration and System Compatibility

Gas detectors don’t operate in isolation—they must report data to control rooms, safety systems, or SCADA platforms.

Before purchasing, verify:

• What kind of signal your system accepts (4–20mA, Modbus, relay)

• Whether you need centralized alarm control

• If the device supports diagnostics or cloud monitoring (optional, but growing)

For legacy systems, analog (4–20mA) is usually enough.
For digital plants or remote monitoring, choose Modbus-enabled detectors with remote calibration support.

5. Cost vs. Safety: How Much Should You Spend?

A reliable ATEX-certified single-gas detector (LEL only) starts at $300–9,000, depending on features.

A fixed 4-gas detector with LEL, H₂S, CO, and O₂ may cost $1,200–2,000+, but it replaces four devices—and reduces wiring, calibration, and installation cost.

In most cases, we recommend:

• Single-gas detector with catalytic LEL sensor for general coverage zones

• 4-gas fixed detector in compact or multi-risk areas (e.g., catalytic reformers, tank entry points)

If your budget allows, upgrade to:

• Infrared LEL sensor

• Modbus + analog combo output

• Remote calibration support

The long-term savings on downtime and maintenance often outweigh the higher upfront cost.

Recommended Combustible Gas Detection Setup for Oil Refineries

Choosing the right gas detection system doesn’t need to be complicated. Based on typical risk zones and compliance needs in oil refineries, here’s a smart starting point that applies to 80% of real-world installations.

This setup uses widely adopted sensor technologies, ATEX-certified devices, and scalable integration options. It’s easy to justify, fast to deploy—and easy to explain to your safety auditor.

1. Fixed LEL Gas Detector for General Zone Monitoring

Best for: pump rooms, pipe corridors, tank farms, and loading areas where only flammable gases are present.

Recommended Configuration:

• Single-gas combustible gas detector (LEL sensor, catalytic or infrared)

• 4–20 mA analog output for legacy system compatibility

• IP65+ flameproof housing

• ATEX-certified for Zone 1 or Zone 2 hazardous areas

Typical price range: $350–700 USD, depending on sensor type (catalytic vs. IR) and housing material (plastic vs. stainless steel).

Simple, reliable, and cost-effective for core flammable gas detection. Ideal when only one risk is present.

2. Fixed Multi-Gas Detector for High-Risk Zones

Best for: compact areas with multiple hazards, such as H₂S, CO, and oxygen deficiency—often found in catalyst units, confined zones, or waste gas handling systems.

Recommended Configuration:

• Industrial Fixed 4-gas detector (LEL + H₂S + CO + O₂)

• Dual output: Modbus RTU + 4–20 mA

• Optional relay for local alarms

• Remote calibration + built-in self-diagnostics

Typical price range: $1,200–2,000 USD, depending on the level of integration, housing material, and certifications.

Reduces total device count, simplifies cabling, and ensures compliance with modern gas safety standards.
Best suited for plants moving toward digitally integrated gas detection systems—especially those connected to SCADA or DCS.

3. Portable Multi-Gas Monitor for Mobile Personnel

Best for: confined space entry, inspection rounds, and maintenance teams.

Recommended Device:

• Portable 4-gas detector (LEL, H₂S, CO, O₂)

• IP67 waterproof/dustproof enclosure

• Visual + audible + vibration alarms

• Optional features: data logging, Bluetooth, or cloud sync

Typical price range: $350–900 USD, depending on features like battery life, sensor type, and communication options.

Critical for individual gas exposure safety. These units complement fixed detectors and meet most refinery PPE requirements.

Final Guidance

This 3-part setup gives you a complete gas safety solution across fixed installations and mobile operations. It’s based on actual usage in refineries—not theoretical specs.

Build your system from there.

When in doubt, go one step higher in performance—especially for high-risk zones. Choosing a detector with faster response or Modbus output now is often cheaper than retrofitting later.