Application of Ammonia Sensors for Ammonia Leakage Detection in Refrigeration Systems
With the continuous development of the refrigeration industry, cold storage has been adopted across all stages of agricultural and livestock products, from harvesting and processing to retail sales. Cold storage slows the respiratory metabolism of agricultural and livestock products to inhibit spoilage and extend shelf life. Cold warehouses generally use low-boiling-point Freon or liquid ammonia as refrigerants. The refrigeration system circulates the coolant, which evaporates under low pressure and mechanical control to absorb heat inside the warehouse and achieve cooling. In liquid ammonia refrigeration systems, ammonia gas detectors are indispensable safety equipment.
Over 80% of cold storage facilities in China’s food freezing industry employ ammonia as the refrigerant. Driven by technological advances and the introduction of comprehensive industry codes and standards, safety requirements for food cold storage have become increasingly stringent. Safety risks associated with ammonia refrigeration systems in cold warehouses have become a core concern in cold storage engineering. To mitigate hazards caused by ammonia leaks and protect personnel and property safety, greater emphasis is placed on rationally designing automatic ammonia leakage alarm systems for ammonia refrigeration machine rooms during cold storage planning, so as to guarantee safe operation of the facilities.
Hidden Dangers of Ammonia Leakage
Ammonia leakage poses a unique hazard to ammonia-based cold warehouses. Once a leak occurs, fire risks emerge first. Ammonia explodes when exposed to open flames at concentrations ranging from 15.5% to 27% by volume. Additionally, ammonia is toxic to humans; exposure can trigger convulsions, fainting, and even death by suffocation.
Root Causes of Ammonia Leakage in Cold Warehouses
Ammonia leaks stem from three primary factors: equipment aging, improper human operation, and inadequate management.
Equipment Aging: As service life extends, equipment degrades to varying degrees. Aging valves and loose spindles degrade airtightness and cause ammonia seepage. Welded joints on internal pipelines may crack with age, while pipeline corrosion and deteriorated flanges also lead to leaks.
Non-compliant Manual Operations: Improper handling can trigger ammonia spills. For instance, liquid ammonia or compressor oil entering the compressor cylinder creates excessive internal pressure, blowing off cylinder heads and causing leaks. Unstable stacked goods may collapse after freezing and hardening, rupturing evaporator pipes. Forklifts operating inside warehouses may accidentally sever wall-mounted evaporator pipes. If operators mistakenly shut off the valve between the compressor and condenser during normal operation, the pipeline segment may burst and leak ammonia.
Solution Scheme
Monitoring Locations
Liquid ammonia storage tank zones, refrigeration equipment assembly workshops, loading and unloading areas, ammonia transmission pipelines
Target Gas for Monitoring
Data Transmission & Interlock Logic
Ammonia detection alarms are installed at all designated monitoring points based on actual on-site conditions of the cold warehouse. Upon detecting ammonia leakage, the equipment transmits real-time ammonia concentration readings to the controller via current signals or wireless communication. The system interlocks with gas cut-off valves to immediately block ammonia supply, activates local exhaust ventilation to rapidly evacuate toxic fumes, and safeguards safe personnel operation and stable equipment performance.
Why Install Ammonia Gas Detectors in Refrigeration Systems?
Ammonia is a colorless gas with a strong pungent odor and lighter than air. Long-term exposure harms human health. Liquid ammonia refrigeration systems require ammonia gas detectors to identify potential ammonia leaks.
Ammonia gas detectors fall into two categories: portable and fixed. Portable ammonia detectors are lightweight and deliver instant concentration readings upon startup. Fixed ammonia detectors consist of two core components: gas detectors and control panels.
Gas detectors are mounted on-site for 24/7 real-time monitoring, relying on electrochemical ammonia sensors to measure ammonia concentrations. Control panels are installed in staffed duty rooms and other easily observable locations to display real-time ammonia levels and trigger audible-visual alarms when concentrations exceed thresholds. They also support interconnection with external devices such as solenoid valves and exhaust fans.
Fixed detectors cannot be installed directly inside cold warehouses, as ultra-low internal temperatures will frost over the detectors or trigger malfunctions.
Both portable and fixed ammonia detectors rely on a critical core component: the ammonia sensor.
Shenzhen Wuliang Sensor Technology Co., Ltd. supplies British DDS electrochemical ammonia sensor models GS+4NH3-100, GS+4NH3-300, GS+7NH3-100 and GS+7NH3-1000. These sensors feature high ammonia sensitivity, suitable for ammonia leakage detection in refrigeration systems, with wide applicability across industrial, mining and environmental ammonia monitoring scenarios.
Working Principle of DDS Electrochemical Ammonia Sensors (GS+4NH3-100 / GS+4NH3-300 / GS+7NH3-100 / GS+7NH3-1000)
Operating on electrochemical principles, target ammonia undergoes redox reactions at the sensor’s working and counter electrodes, releasing electric charges to form a current through the external circuit. Current intensity is proportional to ammonia concentration, enabling quantitative measurement of target gas.
Key advantages: low power consumption, high precision, exceptional sensitivity, wide linear measurement range, strong anti-interference capability, excellent repeatability and long-term stability.
Repeated explosion accidents caused by liquid ammonia leakage in cold storage facilities have brought painful casualties and property losses, sounding a critical safety alarm. Effective prevention and reliable, worry-free liquid ammonia utilization have become urgent issues requiring in-depth reflection. Ammonia leakage incidents occur frequently, mostly due to manufacturers’ neglect of routine ammonia management and monitoring. Industry experts note that liquid ammonia storage is not a complex technical challenge but basic industrial common sense, and daily safety supervision should focus primarily on leak prevention. Experts recommend enterprises conduct daily inspections and install professional ammonia leakage alarms in cold warehouses. Diligent daily management delivers reliable safety protection.
Translation Notes
The missing Chinese character "安 (安全)" in the original text is supplemented as "safety" in full English translation for logical integrity;
Professional industry terms (refrigerant, evaporator, compressor, electrochemical sensor, audible-visual alarm, interlock valve, etc.) adopt standard refrigeration & gas detection industry terminology;
Brand, company and sensor model numbers retain original alphanumeric codes without modification;
Long complex Chinese run-on sentences are restructured into conforming English technical writing syntax while fully retaining technical information;
Hazard concentration range, equipment failure mechanisms and interlock control logic are translated accurately for engineering reference.
