Refrigerant leakage is a common problem affecting cooling efficiency and equipment lifespan in commercial kitchen air conditioners during long-term operation. Due to the high temperature, high humidity, and high concentration of oil fumes in the kitchen environment, air conditioning systems need to be frequently started and stopped to cope with load changes, which exacerbates the aging risk of refrigerant pipes, joints, and welds. Rapid detection of refrigerant leaks requires a combination of environmental characteristics and equipment structure, employing targeted methods to ensure detection efficiency while avoiding misdiagnosis or secondary contamination. The following analysis covers the detection principle, operating procedures, and precautions.
Visual and tactile inspection is a crucial initial screening step. Refrigerant leaks are usually accompanied by the seepage of refrigerant oil, especially at pipe bends, valve connections, and compressor seals, where oil stains easily form. Operators should wear white gloves and touch each section along the refrigerant circulation path (including the evaporator, condenser, expansion valve, and compressor) to observe whether the gloves are contaminated with oil. The presence of localized frost or residual oil after melting ice can also serve as preliminary evidence of a leak. This method requires no specialized tools and is suitable for quickly locating obvious leaks, but its ability to identify minor leaks or hidden areas (such as inside pipes) is limited.
Soap and water leak detection is a low-cost and widely used method. Dilute neutral soap solution to a thick consistency and apply it evenly to suspected leak locations (such as flange connections, welds, pressure gauge interfaces, etc.) with a soft brush. If a leak is present, the escaping refrigerant will form continuous bubbles, and the bubble size is related to the amount of leakage. During operation, ensure proper ventilation to prevent soap solution from flowing into equipment and causing corrosion. For minor leaks, a small amount of nitrogen can be introduced into the system (pressure controlled at 0.1-0.2 MPa) to enhance the leak airflow and increase bubble formation efficiency. This method is suitable for initial screening, but requires manual point-by-point inspection, which is time-consuming.
Electronic leak detectors are the core technology for accurately locating minor leaks. Electronic leak detectors use sensors to capture changes in refrigerant molecule concentration. When the leakage reaches a set threshold, the instrument will issue an audible and visual alarm. During operation, the probe should be moved slowly along the pipeline, focusing on checking the compressor's suction and discharge ports, both ends of the expansion valve, and valve seals. Since kitchen fumes may adhere to the probe, it is necessary to periodically purge the sensor with clean air to avoid false alarms. For newer environmentally friendly refrigerants such as R410A and R32, a compatible leak detector must be selected to ensure detection sensitivity. This method is efficient and accurate, but the equipment cost is high, and it requires professional operation.
The fluorescent leak detection method is suitable for detecting hidden locations or long-term micro-leaks. A special refrigerant containing a fluorescent agent is injected into the system. After running for a period of time, the pipeline surface is irradiated with ultraviolet light. Leak points will show bright yellow-green spots due to the fluorescent agent residue. This method can locate minute leaks that are difficult to detect by other methods, especially suitable for leaks between evaporator fins or on the inner walls of pipes. However, attention must be paid to the compatibility of the fluorescent agent and the refrigerant to avoid affecting system performance, and residues must be thoroughly rinsed off after testing.
Pressure testing is a comprehensive means of verifying the system's sealing performance. With the system shut down, charge with high-pressure nitrogen (pressure adjusted according to equipment specifications, typically 1.5–2.0 MPa), close the valve, and observe the pressure gauge reading. If the pressure drops by more than 5% within 24 hours, a leak is detected. This method can detect overall tightness but cannot pinpoint the specific leak point; further investigation using other methods is necessary. Strict control of the charging pressure is crucial to avoid overpressure damage to the equipment.
Infrared thermal imaging detects leaks by identifying temperature anomalies. Refrigerant leaks cause localized temperature drops, creating a temperature difference with the surrounding environment. Using an infrared thermal imager to scan the pipe surface, the low-temperature area indicates a potential leak point. This method requires no contact with the equipment and is suitable for detecting high-temperature, high-pressure, or difficult-to-disassemble parts, but requires eliminating ambient temperature interference and has higher equipment costs.
Comprehensive detection strategy and preventative measures. Refrigerant leak detection in commercial kitchen air conditioners requires a combination of methods: first, visual inspection to narrow down the leak area; then, using soapy water or an electronic leak detector to pinpoint the leak; and finally, a pressure test to verify overall tightness. During routine maintenance, it is necessary to regularly check whether the pipe fixing supports are loose to avoid fatigue cracking of joints caused by vibration; when changing the compressor lubricating oil, the condition of the oil seals should be checked at the same time; during kitchen renovations or equipment relocation, protect the refrigerant pipes from mechanical damage. Through systematic detection and prevention, the risk of leakage can be significantly reduced, ensuring the efficient operation of the air conditioner.
