Published: September 2026
On July 8, 2026, an ammonia leak at an ice manufacturing facility in Suphan Buri, Thailand, highlighted once again the importance of ammonia safety in industrial refrigeration systems.
The incident occurred at an ice factory in Doem Bang Nang Buat District. According to local reports, ammonia leaked from the plant’s refrigeration system during maintenance work involving a manual valve. Approximately 3,000 students from nearby schools were evacuated, and 36 people were taken to hospitals after being affected by the incident. One of the affected schools was approximately 300 meters from the factory, while another was around 1 kilometer away.
Following the incident, Thailand’s industrial authorities called for tighter inspections of ice factories using ammonia refrigeration systems. Thailand’s Department of Industrial Works (DIW) has also continued to strengthen safety requirements and inspection procedures for factories using ammonia as a refrigerant.
The incident provides an important lesson for ice plants, cold-storage facilities, food-processing factories, and other industrial sites using ammonia refrigeration:
Ammonia leak detection should not be treated as an optional safety accessory. It should be considered an important layer of a comprehensive ammonia refrigeration safety system.
Ammonia, or NH₃, is widely used as a refrigerant in industrial refrigeration because of its excellent thermodynamic performance and long-established use in large-scale refrigeration systems.
It is particularly common in:
Ice manufacturing plants
Cold-storage facilities
Frozen-food processing plants
Food and beverage factories
Large refrigeration systems
Distribution and logistics centers
Ammonia is also known as R717 in refrigeration applications. Unlike many synthetic refrigerants, ammonia has zero ozone depletion potential and is widely recognized as an efficient refrigerant for industrial applications.
However, its refrigeration advantages come with significant safety considerations.
Ammonia is a toxic and corrosive gas. It is colorless and has a strong, pungent odor. A release from a pressurized refrigeration system can quickly create a hazardous atmosphere, particularly inside machinery rooms or other enclosed areas.
A review of chemical accident data in Thailand from 2017 to 2021 identified 237 chemical accidents, resulting in 414 injuries and 25 deaths. The study identified ice manufacturing, frozen-food production, and cold-storage facilities among the industries with relatively frequent chemical accidents, partly because these facilities commonly use ammonia refrigeration systems.
This makes ammonia detection an important consideration for industrial refrigeration safety.
The health effects of ammonia depend strongly on concentration, exposure duration, and the conditions of exposure.
According to the U.S. National Institute for Occupational Safety and Health (NIOSH), the recommended exposure limit for ammonia is 25 ppm as a time-weighted average (TWA) and 35 ppm as a short-term exposure limit (STEL). NIOSH lists 300 ppm as the IDLH concentration, meaning a concentration immediately dangerous to life or health.
OSHA’s permissible exposure limit is listed as 50 ppm as an 8-hour TWA.
Exposure to ammonia can cause:
Eye irritation
Nose and throat irritation
Coughing
Breathing difficulty
Skin irritation
Respiratory injury at higher concentrations
Severe health effects following high-concentration exposure
Because ammonia has a strong odor, people may notice a leak relatively early. However, smell should never be considered a substitute for an ammonia gas detection system.
Human perception varies, and relying on odor alone does not provide continuous measurement, quantitative concentration data, or automatic alarm and control functions.
A properly designed ammonia detection system provides an objective way to monitor the atmosphere and initiate predefined safety actions when ammonia concentration increases.
The July 2026 incident demonstrates why maintenance activities around ammonia refrigeration equipment deserve particular attention.
Public reports indicated that the ammonia leak occurred during maintenance involving a manual valve in the refrigeration system. The release affected nearby areas and led to the evacuation of approximately 3,000 students. Thirty-six people were taken to hospitals for medical attention.
The incident also attracted attention from Thailand’s industrial authorities.
Rather than viewing the event simply as an equipment failure, industrial refrigeration operators can use it as an opportunity to review the complete safety chain:
Detection → Alarm → Ventilation → Isolation → Evacuation → Emergency Response → Inspection → Recovery
A gas detector alone cannot prevent every ammonia release. However, early detection can provide valuable time for personnel and safety systems to respond before a leak develops into a larger emergency.
Thailand has a specific regulatory framework covering refrigeration systems that use ammonia as a refrigerant.
The Department of Industrial Works currently lists the Ministerial Regulation Prescribing Safety Measures Concerning Refrigeration Systems Using Ammonia as Refrigerant in Factories, B.E. 2554 (2011) among its factory safety regulations.
Thailand has also introduced additional requirements in recent years concerning the reporting, inspection, and testing of ammonia refrigeration equipment and related personnel.
The regulatory framework addresses areas including:
Design and installation of ammonia refrigeration systems
Operation and maintenance
Inspection and testing
Ammonia detection
Ventilation
Emergency preparedness
Safety management
For facilities covered by the applicable requirements, ammonia vapor detection equipment is an important part of the safety system, particularly in machinery rooms and relevant working areas.
However, regulatory compliance should not be reduced to simply purchasing a gas detector. The number and location of detectors, alarm thresholds, ventilation, emergency shutdown logic, inspection procedures, maintenance, and emergency response plans should all be considered as part of the overall safety design.
For this reason, a site-specific risk assessment remains essential.
An industrial ammonia gas detector provides a continuous measurement of ammonia concentration rather than relying on workers to recognize an odor or visually identify a problem.
A well-designed system can provide several layers of protection.
Ammonia detectors can continuously monitor areas where leakage may occur, such as:
Compressors
Valves
Pumps
Refrigeration machinery
Ammonia storage vessels
Pipe connections
Pressure-control components
Other potential release points
When the ammonia concentration reaches the configured alarm level, the system can immediately notify personnel.
Industrial ammonia detection systems can be connected to audible and visual alarm devices.
The alarm level should be determined according to applicable regulations, occupational exposure limits, site risk assessment, and the facility’s emergency response procedures.
For example, some facilities may use a low-level alarm around 25 ppm as a conservative reference point, while higher alarm levels may be configured according to the specific risk-control strategy.
There is no universal 25 ppm/50 ppm alarm setting that applies to every ammonia refrigeration installation.
An ammonia detector can also provide output signals to other safety equipment.
Depending on the system design, the detector may communicate with:
Emergency ventilation systems
PLCs
Alarm controllers
Building management systems
Emergency shutdown systems
Remote monitoring platforms
This creates a more integrated response:
Detect → Alarm → Control → Evacuate
The exact interlock logic should always be determined by the site’s engineering design and safety assessment.
Ammonia leaks can occur outside normal working hours.
For this reason, 24/7 monitoring is particularly valuable in facilities that operate continuously.
A fixed ammonia gas detection system can provide continuous monitoring even when fewer employees are present, while remote communication can allow authorized personnel to receive alarm information away from the plant.
There is no single detector layout that is appropriate for every ice plant or cold-storage facility.
Detector placement should consider:
Potential ammonia release points
Refrigeration equipment layout
Room size
Ceiling height
Ventilation airflow
Air movement
Machinery configuration
Access routes
Worker locations
Emergency exits
Applicable local standards and regulations
Particular attention should be given to machinery rooms and areas containing compressors, valves, pumps, and other refrigeration components where ammonia could potentially be released.
Because ammonia is lighter than air under normal atmospheric conditions, the physical behavior of released ammonia should be considered during detector placement. However, actual airflow patterns, temperature, ventilation, equipment configuration, and release conditions can significantly affect gas distribution.
Therefore, detector positioning should be based on engineering assessment rather than applying a fixed distance or detector radius to every installation.
When selecting an ammonia detection system for an ice plant or cold-storage facility, several technical factors should be evaluated.
Electrochemical sensors are commonly used for toxic-gas detection because they can provide sensitive measurement at relatively low concentrations.
The appropriate sensor technology should be selected according to:
Required detection range
Accuracy
Response time
Environmental conditions
Expected operating temperature
Maintenance requirements
Calibration requirements
For applications focused on personnel exposure monitoring, a 0–100 ppm range may be appropriate in some installations. Higher ranges may be necessary where high-concentration leakage detection is also required.
The correct range should therefore be determined by the application’s safety objectives rather than assuming one range fits all facilities.
A faster response can provide more time for personnel and safety systems to react to a developing leak.
When comparing products, operators should review parameters such as response time, accuracy, repeatability, sensor life, and calibration requirements.
For demanding industrial applications, selecting a detector with a rapid response capability can be an important consideration.
A suitable ammonia alarm system should allow alarm thresholds to be configured according to the site’s safety strategy.
Rather than treating a particular value as a universal standard, alarm levels should be determined using:
Local regulations
Occupational exposure limits
Risk assessment
Emergency response procedures
Ventilation performance
Personnel exposure scenarios
Ice plants and cold-storage facilities can present challenging environmental conditions, including:
High humidity
Condensation
Low temperatures
Water exposure
Corrosive environments
The detector enclosure, operating temperature range, ingress protection, sensor design, and applicable hazardous-area certification should therefore be evaluated together.
If the installation is located in a classified hazardous area, the detector should have the appropriate certification for the specific area classification. Ex d IIC T6 Gb and IP66, for example, may be suitable for certain applications, but they should not automatically be treated as mandatory specifications for every ammonia refrigeration facility.
The most effective approach to ammonia safety is not simply installing a detector.
A comprehensive safety strategy should combine:
1. Prevention
Regular inspection, maintenance, appropriate components, and safe operating procedures.
2. Detection
Continuous ammonia concentration monitoring in high-risk areas.
3. Alarm
Clear audible and visual warnings when configured thresholds are reached.
4. Ventilation
Effective emergency ventilation designed for the specific facility.
5. Isolation
Appropriate emergency shutdown and isolation procedures.
6. Evacuation
Clearly defined evacuation routes and emergency procedures.
7. Training
Regular training and emergency drills for employees.
8. Inspection and Maintenance
Periodic calibration, functional testing, sensor replacement, and system inspection.
This layered approach is particularly important because no individual safety device can eliminate every risk associated with ammonia refrigeration.
The July 2026 Suphan Buri ammonia leak is a reminder that ammonia safety should be considered throughout the entire lifecycle of a refrigeration system—not only during normal operation.
Maintenance work around valves, pipes, compressors, pumps, and storage components can create additional risks if isolation, pressure control, work procedures, or emergency preparedness are inadequate.
For ice plants and cold-storage operators, several practical questions are worth asking:
Where are the most likely ammonia release points?
Are ammonia detectors installed in appropriate high-risk areas?
Are alarm thresholds based on a documented risk assessment?
Can alarms be heard and seen throughout the required area?
Can the detection system communicate with ventilation or control systems?
Are detectors regularly calibrated and tested?
Are emergency procedures documented?
Are employees trained to respond to ammonia alarms?
Are emergency drills conducted as required?
Does the refrigeration system comply with applicable Thai regulations and engineering requirements?
These questions can help transform ammonia safety from a reactive emergency response into a proactive risk-management system.
For ice plants, cold-storage facilities, and other industrial refrigeration applications, an ammonia gas detection system should be selected according to the actual site conditions rather than simply choosing the highest specification available.
A properly designed solution may include:
Fixed ammonia gas detectors
Ammonia alarm controllers
Audible and visual alarms
4–20 mA outputs
Relay outputs for equipment control
Digital communication interfaces
Remote monitoring
Calibration and maintenance services
Integration with ventilation and emergency control systems
At CCEsafety, we provide industrial gas detection solutions designed for demanding industrial environments.
Our ammonia detection solutions can be configured according to project requirements, including sensor range, alarm levels, communication interfaces, enclosure protection, and system integration.
For projects in Thailand or other markets, product selection and installation should be evaluated against the applicable local regulations, hazardous-area requirements, site conditions, and engineering design.
The Suphan Buri incident demonstrates how an ammonia release at an ice factory can affect not only employees but also nearby communities and public facilities.
For facilities using ammonia refrigeration, safety should not begin after an alarm occurs.
It should begin with:
Risk assessment.
Reliable detection.
Early warning.
Effective ventilation.
Emergency response.
Regular inspection and maintenance.
An industrial ammonia gas detector is not a replacement for proper refrigeration-system design or safe operating procedures. Instead, it is an important layer within a broader safety system—one that can provide critical early warning when ammonia concentration begins to rise.
If you operate an ice plant, cold-storage facility, frozen-food factory, or other industrial facility using ammonia (R717) refrigeration, contact CCEsafety for an ammonia gas detection solution tailored to your application.
Our technical team can assist with detector selection, alarm configuration, system integration, installation planning, calibration, and maintenance based on your facility layout and refrigeration system requirements.
Early detection can make the difference between a manageable leak and a major emergency.
What is an ammonia gas detector used for?
An ammonia gas detector continuously monitors the concentration of NH₃ in the surrounding atmosphere and can trigger alarms when configured concentration thresholds are reached.
What ammonia concentration should trigger an alarm?
There is no single alarm threshold suitable for every installation. Alarm levels should be determined according to applicable regulations, occupational exposure limits, site risk assessment, and emergency response procedures. NIOSH lists 25 ppm as a TWA REL, 35 ppm as a STEL, and 300 ppm as the IDLH concentration.
Where should ammonia detectors be installed in an ice plant?
Detector locations should be determined according to potential release points, machinery layout, ventilation, airflow, room configuration, and applicable standards. Machinery rooms and areas around compressors, valves, pumps, and other potential leak sources typically require particular attention.
Is an explosion-proof ammonia detector always required?
Not necessarily. The required certification depends on the hazardous-area classification and applicable regulations. Where a classified hazardous area exists, the detector should have certification appropriate for that specific area.
Does Thai law require ammonia detection in refrigeration facilities?
Thailand has specific safety regulations for factory refrigeration systems using ammonia, including requirements related to ammonia detection and other safety measures. The Department of Industrial Works currently lists the B.E. 2554 (2011) regulation and subsequent requirements concerning inspection and testing of ammonia refrigeration systems.
Can an ammonia detector automatically start an exhaust fan?
Depending on the system design, an ammonia detector can provide relay, analog, or digital signals to ventilation and other control systems. Whether automatic activation is appropriate should be determined by the facility’s engineering and emergency-response design.
