How to Choose a Leak Detector
It is essential that you choose the best refrigerant leak detector that suits your requirements. But what are the qualities that you should look for before selecting a product? Let’s find out:
Works Fast
A device that works fast is considered the best leak detector as it allows you to reach different locations to check on leaks quickly. You should look for detectors with little warm-up time, quality sensors, and instantaneous time response.
Detects a Wide Variety of Refrigerants
Although you may not need a leak detector capable of detecting all types of refrigerant make sure that the one you choose is capable of detecting the refrigerant you are going to be working with. Devices that detect a variety of refrigerants are usually expensive, therefore apply your expertise and check your field applications before picking the right one.
How to Choose and Why Use Leak Detectors?
Refrigerant leak detection
The chart below shows the most common groups of refrigerants we use. With the wide variety of refrigerants now available we have to ensure that the type of leak detector we are using is both suitable and SAFE to use with the refrigerant in the system. Most electronic leak detectors are suitable for CFC, HCFC and HFC’s. Caution should be taken to use suitable electronic leak detectors with HC’s which are flammable. We must not forget soapy water as a very effective leak detector. Many people discount it, but for finding leaks it is possibly the most effective method and lots of people have certainly used it to successfully find some very small leaks.
Leak Detector Maintenance
Having selected the appropriate leak detector for the job it is important to be sure the equipment is working. Most of the electronic leak detectors need regular calibration and the corona discharge and heated diode types require sensor changes at regular intervals. Read the manufacturers instructions as a leak detector that is not working is not obvious to the user. DO NOT open a bottle of refrigerant over your detector head to prove that it is working – even a sensor that is spent will sense that, come to that so would you!
How To Choose A Leak Testing Method That’s Best For Your Needs
Choosing the right method
Several factors need to be considered when it comes to choosing a leak detection method.
The first question to ask is what are the tightness criteria that need to be detected? Highly sensitive helium leak detection is the best way of detecting leak tightness in the range of 1 x 1–7 mbar*l/s or lower, but if your required leak rate is above this value, then there are numerous other possibilities.
Another question to ask is how important are cycle/throughput times? If your application involves testing of 100% of components or parts in a production line, then speed is an important consideration. If your leak testing challenge is limited to sample testing and laboratory applications, then throughput times aren’t such a critical factor in your choice of leak testing technology.
The design of the part under test – and specifically the design of the seals – should also be considered. Leak testing often involves pressurising a part to its maximum operating pressure, and some seals will perform better under higher pressure and vacuum than others.
Best Methods for Refrigerant Leak Detection
Ultrasonic
Uses sound amplification. Acts on the high frequency sound pitch that occurs when gas passes through an orifice. This method may not be accurate on small leaks because not enough sound is generated through a small orifice.
Corona Discharge
Air is pulled through an energized electrical field around an electrode. Refrigerant gases are broken down by the electric arc (corona discharge) and detected by the sensor. The presence of a detectable gas changes the current flow in the electrode and triggers an alarm. Gases other than refrigerant can trigger an alarm, giving the appearance of a leak when there may not be one (false alarm). The sensor may degrade over time and need to be replaced. It should be checked regularly against a calibrated reference leak to ensure correct operation. Do not use in the presence of combustible gases.
Heated Diode
Air is pulled over a heated diode. Halogenated gases are broken down by the heater resulting in a change in current flow through the diode. The change in current through the diode triggers an alarm. The heated diode sensor is sensitive to excess refrigerant in addition to other contaminates such as moisture and oil resulting in sensor degradation. Because of sensor degradation, the heated diode sensor must be checked regularly for accuracy and replaced within 100 hours of use. When exposed to contamination including excess refrigerant, the sensor could fail much more quickly. For this reason, sensors must be checked regularly against a calibrated reference leak to ensure correct operation. Do not use in the presence of combustible gases.
Heated Electrolyte
Air is pulled over a heater that is in the presence of an electrolytic material that reacts with the broken down halogenated refrigerant gasses. Halogenated gases result in a change in current flow between the heater electrode and the electrolyte which triggers an alarm. Like the heated diode sensor, the electrolytic sensor is sensitive to excess refrigerant and other contaminants resulting in sensor degradation. Excess refrigerant exposure can have a quick impact on sensor life. A heated electrolyte detector must be checked regularly with a calibrated reference leak to ensure that it can accurately detect a refrigerant leak. Do not use in the presence of combustible gases.
Infrared
Air is pulled through an optical window in the infrared sensor. Refrigerant gases absorb IR Radiation. The optical sensor senses this and triggers an alarm, depending on how much IR has been absorbed. This technology is very accurate and has been the technology of choice in lab settings for many years. It has only recently (last 5 years approx.) been introduced to the field in the form of portable hand held leak detectors. The refrigerant isn’t broken down by heat and doesn’t directly contact the sensor, thus the sensor isn’t subject to contamination. Sensor life expectancy is over 1000 hours or the life of the leak detector. To ensure accuracy, the infrared detector should be checked regularly against a calibrated reference leak.
Refrigerant Leak Detection Methods
How to Find a Refrigerant Leak
As an HVAC professional, you have a business responsibility to find and fix refrigerant leaks through preventative and corrective maintenance. In addition, various regulatory jurisdictions at the local, state, and federal levels (e.g., EPA 608) require regular leak inspections.
These requirements to find refrigerant leaks can be successfully met by employing the best refrigerant leak detection method(s) for your job needs. Refrigerant leak detection methods include, but are not limited to:
soap bubble method;
fluorescent dye method; or
electronic leak detection method.
As you can see, there are numerous methods that you can use; each with their own benefits, and this is where you need to pay close attention. That’s why we are going to start by looking at the more traditional methods and then move to the newer methods. By the end, you will find out which methods are best.
Soap Bubble Method
The soap bubble method is a mainstay that has been relied upon by residential technicians for decades. It’s fairly self-explanatory. In essence, you apply soapy water or a leak detection spray to see if there are leaks at certain points. Bubbles should appear at leakage points.
While common and trusted, what undermines the soap bubbles method is the fact that it can be difficult to pinpoint leaks under certain conditions, such as if the leak is very small or if it is windy outdoors. That’s why it may be most beneficial for you to use the soap bubble method in combination with another method, particularly with one of the electronic leak detection methods.
