Fluorescent Detection Spots Leaks
Prompt leak detection helps prevent refrigerants from escaping into the environment, reduces CFC emissions and minimizes damage to the ozone layer. In addition, by detecting leaks early in the game, you drastically cut the cost of expensive replacement refrigerants.
Lurking behind this never-ending problem is the fact that refrigeration leaks cannot be repaired until they are located. The solution is a preventive maintenance program that puts a high priority on leak detection. Many facility managers and plant engineers have found that fluorescent leak detection is the fastest, easiest and most accurate method to pinpoint even the smallest leaks in all types of refrigeration systems. The sooner leaks are located, the earlier they can be repaired to keep energy and refrigerant losses to a minimum.
Fluorescent leak detection works with all types of refrigerants regardless of surrounding conditions: noise, wind or air currents, tight spacing around suspected leak sites, or the size and configuration of the system. It requires a minimum of time and labor to inspect the entire system, and the entire system does not have to be shut down simply to perform an inspection. In the past, there was one drawback to fluorescent leak detection: it was hard to see the dye fluoresce in bright sunlight. However, recent advances in lamp technology have resulted in powerful ultraviolet (UV) and UV/blue light lamps that have put that problem largely to rest.
Fluorescent leak detection works with any refrigerant, including R-11, R-12, R-22, R-113, R-114, R-123, R-500 and R-502 systems, which are lubricated with mineral oils. Dyes are also available for R-134a, R-404a, R-507 and many other alternative refrigerants and blends that use polyolester, alkyl benzene or PAG lubricants -- even for low-temperature systems.
How It WorksFirst-time users of fluorescent leak detection always are in for a pleasant surprise. They simply add fluorescent dye to the refrigeration system and allow it to circulate. A solvent-free dye is best because it will not harm or impair the properties of the lubricant used in the system, which could cause excessive wear or damage to system components. Alkyl benzene is the most common lubricant in low-temperature applications.
Wherever there is a leak, the dye-lubricant mixture escapes and remains at all leak sites. Then all the user has to do is scan the system with a high-intensity ultraviolet or UV/blue light lamp. When exposed to the light, the dye glows a bright yellow-green color and clearly reveals the exact location of each and every leak -- even those that cannot be found with other methods and that are as small as 1/8 oz (3.5 g) per year. With ultra-powerful inspection lamps, the glowing dye can be seen from as far away as 20' (6 m), making it easy to spot leaks in overhead systems.
New, powerful and portable leak-detection flashlights make the job even easier because there are no power cords to become snagged on the refrigeration system's components. Some use super-high-flux LED technology that delivers as much power as 100 W lamps that must be plugged into electrical outlets.
Another reason why fluorescent leak detection makes a good addition to preventive maintenance programs is that the dye remains safely in the system until the lubricant is changed. Checking the system periodically lets the user quickly see if any new leaks have developed since the last inspection. This way, leaks are caught before substantial amounts of refrigerant escape, and equipment continues to run smoothly and efficiently.
Always be sure to wipe away any remaining dye from the leak site after the repair is completed to eliminate the possibility of false-leak indications during future inspections. A good practice is to attach a tag to every system that has dye in it. Because fluorescent leak detection is so easy to use and takes so little time to complete the inspection of any system, labor costs are minimized. PCE
Sidebar: For best results in detecting leaks with fluorescent dyes in a process refrigeration system, consider the following:
Spot Leaks More Efficiently
- Wear fluorescence-enhancing glasses for best results.
- Use a "universal" polyolester-based dye when the lubricant is unknown.
- Circulate the dye for a longer time for a brighter glow.
- Use the system pressure to bleed the hose from the system back to the front valve.
- Use the pressure from the manifold to bleed the hose from the manifold.
- Use a cloth to wipe residual fluorescent dye from low-loss fittings so no false leak indications occur in plunger-type, manual dye injectors.
- Isolate and depressurize an oil reservoir when possible so that bottled dye can be poured and added easily to the refrigeration system.