What is Electronic Leak Detection?
Maybe you’ve heard the term and are wondering, what is electronic leak detection? And how can it help me? Today’s homes are primarily built on concrete slabs, which makes early leak detection difficult. If your water usage fluctuates without incident or you notice an increase in usage, there may be a small to substantial leak under your slab, without you having any way to know about it. All water leaks create some amount of noise, even if imperceptible to our ears. Different types of leaks have different sound frequencies determined by the degree of pressure in the pipes. An electronic leak detector can pick up these frequencies, and a professional who is trained to understand the acoustics of plumbing can decipher these sounds. An electronic leak detector can find leaks in toilets, drains, water systems, steam pipes, and pipes that transport other liquids, such as oil.
The electronic leak detector has a transducer which is sensitive to the types of sound that come from pipe systems. When a sound is registered on the machines it is transmitted to the security system at a higher frequency. A plumbing technician will assess all information regarding where a potential leak may be happening and use an electronic leak detector, line tracing equipment, camera inspection, and static pressure testing to locate the specific source of the leak. Even a very small leak can cause cracks in the slab and flooding damage. By utilizing the current technology and understanding how they work to create a full ‘picture’ of what is happening out of sight, a leak can be detected long before the homeowner would become aware, avoiding severe and costly water damage to their home.
HVAC AC Refrigerant Leak Detectors
Refrigerants leak from HVAC systems due to the deterioration of joints, fittings, or parts that are welded, which become faulty with time. Leaks might be low as 1 oz every few years, but also might be much greater, such as a few ounces per day. Losing refrigerant means compromised performance of an AC cooling system, as well as greater expenses.
Measuring refrigerant leaks is important from two points of view: economic loss and environmental pollution. EPA rules mandate proper practices in refrigerant leak detection and you want to ensure compliance with these regulations.
What methods do are used to find leaks in HVAC AC cooling systems?
Traditionally, an HVAC service tech would use the soap bubble test, a visible method to detect leaks of any refrigerant. However, this method is not the most accurate and is difficult to implement in hard-to-reach places.
Another method, using a fluorescent dye, is also a visible way to see leaks. It works with any refrigerant; however, a dye must be added to the system, and a special UV light be used in the inspection. Again, inspection of leaks in hard-to-reach places is difficult to perform.
Currently, the most popular method is facilitated by the use of electronic refrigerant leak detectors. This method is the most accurate; however, one must remember to monitor the sensor’s condition as well as calibrate the instrument periodically.
What are a types of electronic leak detectors?
Corona discharge is one of the most traditional types. In this method, air with gases passes through an electrical field around an electrode and an electric arc (discharge) breaks down refrigerants, which are detected by a sensor and “reported” with an alarm signal (sound).
Heated diode refrigerant leak detector is a second popular type in which a heater close to a diode breaks down gases, yielding a change in current flow through diode. Such a change triggers the alarm resulting in audible leak detection.In the heated electrolyte method gases are broken down as they go over electrolytic material in the sensor. Again, the resulting change of current flow triggers the audible alarm.
Sensors using corona discharge, heated diode, or heated electrolyte detectors need to be changed quite often, so proper monitoring of their use is necessary.
Infrared refrigerant leak detectors are the best option, as their sensors typically last over 1000 hours – equivalent to over 5 years of use. In this method an air sample with gases passes through an optical window of a sensor and the refrigerants absorb IR radiation. An alarm gets triggered by the amount of IR radiation absorbed and carried over the sensor. This is by far the most accurate method, as it had been used in laboratory settings for many years and now is available to HVAC technicians.
Finally, there is an ultrasonic refrigerant leak detector, one that uses sound amplification to detect leaks. Gases passing through orifices or breaks in pipes produce a high pitch sound not detectable by a human ear but easily recorded by ultrasonic leak detector. The method is great, but the main shortcoming is that very small leaks don’t produce enough sound and they might not be detectable.
High Voltage Electronic Leak Detection (HVELD)
High Voltage Electronic Leak Detection (HVELD) can be performed on vertical or horizontal surfaces under dry conditions. The principle of the HVELD process involves a generator that delivers an adjustable stabilized direct current (DC) output voltage for the detection of breaches to the electrically insulated roof or waterproofing membrane.
The generator emits a calibrated voltage discharge which conducts through membrane penetrations to a grounded earth lead, such as a metal drain body or steel reinforcing embedded in the concrete slab. Should the current make contact with the ground, this will complete the circuit emitted by the generator. An audible beep from the test equipment alerts the technician of the breach. Small sparks can sometimes be seen or heard when a breach location is contacted by the probe.
The initial test voltage is based on the thickness of the waterproofing membrane and is verified (calibrated) by creating a sample breach in a typical section of membrane being tested to ensure detection levels are appropriate. In the case of liquid applied membranes, properly calibrated HVELD equipment can also detect locations where the membrane does not meet the minimum thickness requirements, even if no breach is present.
Multiple false positives are possible with this type of testing if the equipment is not properly calibrated for project specific materials. Due to the high voltage, testing should not be performed in inclement weather or in wet or moist conditions for the safety of the testing operator. HVELD is also not successful if the membrane is conductive, such as black ethylene propylene diene monomer (EPDM).
HVELD can only be performed over conductive substrates, such as metal decking and concrete. If a conductive substrate is not present, it is possible to create a conductive substrate by installing a metal mesh or screen prior to the installation of the waterproofing membrane. However, the waterproofing membrane manufacturer must be consulted to confirm that the presence of an embedded screen or mesh material will not adversely affect the membrane material or void the warranty.
Low Voltage Electronic Leak Detection (LVELD)
Low Voltage Electronic Leak Detection (LVELD) is performed on horizontal surfaces using water as a conductive medium on the surface of the waterproofing membrane. Multiple types of LVELD testing equipment and setups are available. The principle of the LVELD process involves a perimeter conductor loop placed on the surface of the membrane. The conductor loop is then connected to an electrical pulse generator. The generator is also connected to the grounded portion (e.g., reinforcing steel or a metal drain body) of the substrate below the membrane.