One of the most common problems encountered when servicing air conditioning or heat pump equipment is refrigerant loss due to leaks. Leaks usually result from poor installation practices, physical damage, or factory defects. Often these leaks are very tiny, allowing minuscule quantities of refrigerant to continuously escape to the atmosphere without giving any sound or visual sign to aid in detection. Leaks result in steadily deteriorating system performance and may eventually cause the need for a costly repair. In addition to poor system performance, damage to the environment will be caused by the release of CFC and HCFC refrigerants into the atmosphere.
Leak detectors like the one shown in Figure 1-12 a reused to:
• Check for small leaks after making a major repair to a system.
• Check for leaks be fore evacuating a system because moisture can enter the system through the leak during evacuation or pumpdown.
• Check for leaks when the required vacuum level cannot be achieved while evacuating a system.
Many types of leak detectors are available, including simple bubble solutions and detection instruments such as halide torch detectors, electronic leak detectors, ultrasonic leak detectors, and ultraviolet lamp and fluorescent-additive detectors. Because leak detection is so important and refrigerant leaks in a system can be very tiny, sensitive leak detection instruments are usually required. Leak detectors a re available for systems using CFC, HCFC, o r HFC refrigerants. (See Section 3 for specific information about CFC, HCFC, and HFC refrigerants.) For many reasons, including price, accuracy, and ease of use, the electronic leak detector is used by most technicians who service residential and light commercial systems. Figure 1-13 shows typical electronic leak detectors.
Electronic leak detectors generally consist of a probe connected to a control unit. They have an air pump that draws sample air through the detector tip and over the sensing element. When leaking refrigerant is detected, the electronic detector sounds an audible alarm or gen e rates a bright flashing light at the probe tip, or both. Features to look for in an electronic leak detector include:
• The ability to sense leaks in contaminated areas.
• Leak sensitivity that detects 1/2 oz. per year.
• Battery-opera ted ; instant warm-up if 115 VAC powered.
• Audible and visible leak indicators.
• Sensor not contaminated by large doses of refrigerant or other gases such as nitrogen.
• Long flexible probe for hard-to-reach areas.
• The ability to detect a variety of refrigerants with little or no modification.