Tech Page: Refrigerant Leaks
What Causes a leak?
Several factors can contribute to a leak in a refrigeration system, but common causes are faulty manufacturing and improper maintenance. Joints that have been brazed poorly or improper flared connections can lead to a leak.
LEAK TYPES Static leak: The most common type of leak. The unit will exhibit a leak although it is off and equalized.
Pressure leak: These leaks don’t appear until pressure builds in the system.
Expansion leaks: These leaks usually occur as the result of high heat. High ambient temperatures, condenser blockage, and the defrost cycle can cause expansion leaks.
Vibration leaks: These leaks usually occur when a system is under operation. Unit rotation, valve actuation, and refrigerant flow are associated with this type of leak.
Combination leaks: In some cases, more than one condition causes the system to leak. One example is vibration with high temperature.
Cumulative leaks: These involve a number of small individual leaks that can sometimes be too small to detect with standard tools.
Problem Factors:
When trying to detect a leak, there are several factors that can affect the accuracy of whichever method you use.
Ambient light: This can wash out the response of visual detectors and can cause difficulty finding the leak. Using a UV lamp can sometimes help with this problem.
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Ambient sound: Background noise can interfere with the ultrasonic leak detector, resulting in an inaccurate reading.
Wind and air currents: When using detection methods like the halide torch or an electronic detector, wind and air currents can cause inaccurate readings. These instruments need to pick up on gases in the air, and windy conditions can make this difficult.
The Clean Air Act
Section 608 of the Clean Air Act Amendments makes repairing refrigerant leaks mandatory. Because refrigerants can be harmful to the environment, it is against the law to not maintain or repair systems leaking above a certain rate.According to the Environmental Protection Agency (EPA), Section 608 says that when “an owner or operator of an appliance that normally contains a refrigerant charge of more than 50 pounds discovers that refrigerant is leaking at a rate that would exceed the applicable trigger rate during a 12-month period, the owner or operator must take corrective action.”
How to Detect Leaks:
There are a few methods or instruments that can be used to discover leaks in a refrigeration system. These include:
Bubble solution: If a system is suspected of leaking, a soapy solution can be applied to the area where the leak is thought to be. If refrigerant is leaking from the area, bubbles will begin to form from the solution. This is thought to be one of the oldest and simplest procedures for finding leaks.
Electronic detectors: A number of these detectors can be found on the market. When an electronic detector comes in contact with the gases from a halogenated refrigerant, the detector will sound an alarm to notify of the leak.
Ultrasonic detectors: These instruments are said to “hear” leaks. If there is a leak in the system, the ultrasonic detector will pick up on the inaudible, high-pitched sound of the leak and sound an audio-visual alarm.
Halide torches: When this instrument comes in contact with a refrigerant, the flame of the torch turns to green. When the torch is exposed to CFCs or HCFCs, the color of the flame will change, indicating a possible refrigerant leak.
Fluorescent leak detection: Some leaks can be found by using fluorescent dye and an ultraviolet light. The dye is injected into the refrigeration system. If the system is leaking, the dye will emerge at the leak point. It can be detected by shining the UV light. The UV light will cause the dye to glow a bright yellow or green color.
Trigger Rates
For an appliance with a refrigerant charge of 50 lbs, the following leak rates over a 12-month period are applicable:
Commercial refrigeration: 35%
Industrial process refrigeration: 35%
Comfort cooling: 15%
All other appliances: 15%
Owners and operators have up to 30 days to repair the leak from the day it is discovered. Extra time can be permitted for industrial process equipment. If leaks are not fixed within the required time, harsh fines can be issued.
The EPA also offers two certification exams which must be taken by technicians before they can handle certain refrigerants. These certifications are Section 608 and Section 609.
For more information on the certification exams and on repairing refrigerant leaks, go to www.epa.gov (website).
For Tech Page Information or to request copies, contact J.J. Siegel, training & education editor; 248-244-1731; 248-362-0317 (fax); siegelj@bnp.com (e-mail).
Publication date: 05/21/2001