Enhance Gas Safety with Intelligent Detection, Ventilation, and Emergency Shut-Off Control

Combustible gas leaks can quickly escalate into serious safety incidents if not addressed immediately. In LPG cylinder rooms, natural gas boiler rooms, commercial kitchens, and gas distribution facilities, simply sounding an alarm is often not enough.

An effective gas safety system should not only detect a leak but also initiate automatic actions to reduce gas accumulation and isolate the gas source before conditions become dangerous.

The HazenFire AT-FG99 Gas Alarm Controller is designed to serve as the central control unit for comprehensive gas leak protection systems. When connected to compatible LPG or natural gas detectors, it provides real-time monitoring, alarm management, exhaust fan control, and emergency gas shut-off valve activation from a single platform.

Why a Basic Gas Alarm Is Not Sufficient

Detecting combustible gas is only the first step in preventing an incident.

When gas leakage occurs, several actions may be required simultaneously:

• Detect the gas concentration increase
• Alert personnel through audible and visual alarms
• Activate ventilation equipment
• Reduce gas accumulation within the protected area
• Shut off the gas supply if dangerous conditions develop
• Maintain alarm status until the area has been verified as safe

Without these coordinated actions, gas may continue to accumulate even after an alarm has been triggered.

This is why modern facilities increasingly use integrated gas alarm and control systems.

The Role of the HazenFire AT-FG99 Gas Alarm Controller

The HazenFire AT-FG99 is designed to work alongside external combustible gas detectors rather than performing gas sensing directly.

The controller acts as the command center of the gas safety system by:

• Supplying 24V DC power to connected detectors
• Receiving gas concentration data through RS485 communication
• Displaying gas concentration and system status
• Managing high and low alarm conditions
• Providing audible and visual alarm notifications
• Controlling exhaust fans through relay outputs
• Activating emergency gas shut-off valves
• Monitoring detector and communication faults

With support for up to 99 connected detectors, the AT-FG99 is suitable for both small installations and large industrial gas monitoring networks.

How the Gas Leak Control System Works

A typical HazenFire gas protection system follows a simple but highly effective sequence:

Detection and Response Process

Gas Detector

HazenFire AT-FG99 Controller

Sound & Light Alarm Activation

Exhaust Fan Operation

Emergency Gas Shut-Off Valve Activation

As gas concentration rises, the detector sends alarm information to the controller through RS485 communication.

The controller then:

• Displays alarm status
• Activates visual and audible warnings
• Executes programmed relay outputs
• Starts ventilation equipment
• Triggers emergency gas isolation when required

This coordinated response helps minimize gas accumulation and reduce risk.

Automatic Exhaust Fan Control for Gas Ventilation

Why Ventilation Matters

Ventilation plays a critical role in reducing combustible gas concentrations before they reach dangerous levels.

By removing accumulated gas from enclosed spaces, exhaust fans help improve safety and provide additional response time for personnel.

HazenFire AT-FG99 Fan Control Solution

The AT-FG99 can automatically control ventilation equipment through its relay outputs.

When a configured alarm threshold is reached:

• The alarm activates
• The assigned relay energizes
• The exhaust fan starts operating
• Ventilation continues until manually reset

For most applications, the fan output can be configured as a maintained output, allowing ventilation to continue operating throughout the emergency condition.

Important Engineering Considerations

The controller relay can directly control loads up to:

• 250V AC
• 5A current
• 500W power

For larger ventilation systems, an external contactor or control panel should be installed to switch the higher-power load safely.

Benefits

• Faster gas dilution
• Reduced accumulation risk
• Improved emergency response
• Automatic operation without manual intervention

Emergency Gas Shut-Off Valve Control

Stopping the Gas Supply at the Source

In many combustible gas applications, shutting off the gas supply is one of the most important emergency actions.

Once a leak is detected, isolating the gas source helps prevent additional fuel from entering the affected area.

HazenFire AT-FG99 Pulse Output Control

The AT-FG99 includes a dedicated Output 2 specifically designed for emergency gas shut-off valve control.

Unlike conventional maintained outputs, Output 2 provides a 3-second pulse signal.

Operating Sequence

Gas Leak Detected

Controller Receives Alarm

Output 2 Activates

Valve Receives 3-Second Pulse

Gas Supply Closes

Power Automatically Removes After 3 Seconds

This pulse-based operation matches the requirements of many emergency shut-off valves that only require a short electrical signal to close.

After activation, the valve remains mechanically closed until manually reopened.

Advantages

• Prevents continuous valve energization
• Protects valve components
• Supports emergency isolation procedures
• Matches common gas shut-off valve designs

Multi-Level Alarm Strategy for Enhanced Safety

The HazenFire AT-FG99 supports independent Low Alarm and High Alarm settings for each connected detector.

This allows facilities to implement a staged response strategy.

Low Alarm Response

The low alarm level provides an early warning before gas concentrations become critical.

Typical actions include:

• Activating audible and visual alarms
• Starting ventilation equipment
• Sending warning notifications
• Alerting operators

High Alarm Response

If gas concentration continues to increase, the high alarm initiates a more aggressive response.

Typical actions include:

• Maintaining alarm activation
• Continuing exhaust fan operation
• Activating emergency shut-off valves
• Triggering additional safety systems
• Sending alarm signals to supervisory systems

This layered approach helps improve safety while minimizing unnecessary disruptions.

Manual Reset for Safer Recovery

Safety systems should not automatically return to normal simply because gas levels temporarily decrease.

The HazenFire AT-FG99 uses a manual reset strategy to ensure that alarms and relay outputs remain active until personnel verify that:

• The leak source has been repaired
• Gas concentrations are safe
• The area is ready for normal operation

This approach helps prevent accidental system resets and improves operational safety.

Reliable Communication and Detector Integration

The AT-FG99 communicates with connected gas detectors using RS485 technology.

Key communication features include:

• Stable digital communication
• Long-distance detector connections
• Centralized monitoring
• Detector fault indication
• Communication fault supervision

Correct wiring, shielding, and grounding practices help ensure reliable operation and accurate alarm reporting.

Important Installation Considerations

For optimal performance, engineers should verify the following before commissioning:

Detector Compatibility

The connected detector must match the target gas being monitored, whether LPG, natural gas, or another combustible gas.

Fan Load Verification

Loads exceeding 5A or 500W should be controlled through an external contactor.

Valve Compatibility

Emergency shut-off valves must support pulse-based activation and be compatible with the controller’s output characteristics.

Dedicated Power Supply

The controller should operate from a dedicated electrical circuit to maximize reliability.

Proper Installation Environment

Install the controller in a clean, protected location away from:

• Water exposure
• Oil contamination
• Corrosive atmospheres
• Mechanical damage

Typical Applications

The HazenFire AT-FG99 is suitable for:

• LPG cylinder storage rooms
• LPG manifold systems
• Natural gas boiler rooms
• Commercial kitchens
• Industrial gas supply systems
• Pipeline valve stations
• Utility service rooms
• Fuel gas storage facilities
• Energy infrastructure projects

The quantity and placement of detectors should be determined according to site conditions and project requirements.

Why Choose the HazenFire AT-FG99?

The HazenFire AT-FG99 Gas Alarm Controller combines gas monitoring, alarm management, ventilation control, and emergency shut-off functions into one centralized platform.

Key Features

• Supports up to 99 gas detectors
• RS485 digital communication
• High and low alarm configuration
• LCD concentration display
• Audible and visual alarm indication
• Four programmable relay outputs
• Automatic exhaust fan control
• Dedicated 3-second pulse output for emergency shut-off valves
• Manual reset functionality
• Detector fault supervision
• Communication fault monitoring

Conclusion

Protecting LPG and natural gas facilities requires more than simple gas detection. Effective gas safety systems must coordinate detection, warning, ventilation, and gas isolation to reduce risk and improve emergency response.

The HazenFire AT-FG99 Gas Alarm Controller provides a comprehensive solution by integrating combustible gas monitoring with intelligent fan control and emergency shut-off valve activation. Whether deployed in boiler rooms, LPG storage areas, commercial kitchens, or industrial gas facilities, it helps operators respond faster, improve safety, and maintain better control during gas leak incidents.

For organizations seeking a reliable gas alarm control solution, the HazenFire AT-FG99 delivers the functionality and flexibility needed for modern combustible gas protection systems.