Non-invasive leak detection techniques: How service techs can identify leaks in vinyl-lined pools and rule out false positives

by habiba_abudu | January 22, 2020 9:49 am

By Joe Dolan and Darren Merlob

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Electronic leak detection technology has come a long way since it was first introduced for the purposes of finding leaks in vinyl-lined pools. Today, the tools used to listen for leaks and identify areas where voltage finds a ground, or to simply locate a tear in a liner, have made the job much easier. Complete leak detection kits are designed to put a voltage inside the pool vessel and use specially designed probes to identify where the voltage finds a ground. Using these tools in combination with a method of first listening for leaks with hydrophones, then detecting a voltage applied with a small transmitter, allows technicians to detect leaks quickly and accurately. Not only does this technology offer pool professionals an opportunity to enhance productivity, but it also allows them to increase their workflow, take on more clients, and grow their business.

Listening for the leak

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When approaching a client’s vinyl-lined pool, a technician should use a listening device around suspect areas (where leaks commonly occur) before applying electric voltage to test for leaks.

Hydrophones (highly sensitive microphones designed to be used in water) can pick up the sounds of leaks in areas commonly known to produce problems, either over time or due to any errors made during pool construction. This device allows users to zero-in on even the smallest leaks, whether it is from a crack in a pipe, in a light niche or conduit, under a drain cover, or in a return fitting or spa jet.

The technician begins by dropping the hydrophone into the pool and listening for the sound of leaks from inside the pool shell with an amplifier. The service tech will first listen around lights, wall protrusions, including return fittings and spa jets, step tracks and stair flanges, inside skimmers, and around drains and drain pots. Common areas such as those behind the pool surface where cold joints appear can also cause leaks when the areas separate and wear.

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When a pool leaks, the weight of the water pushing out of a crack creates a distinct sound, which can be picked up by a hydrophone. The closer the hydrophone is to the leak, the louder it becomes. This non-invasive technique simply requires the technician to listen to a ‘static’ pool, i.e. pool full, equipment off. With the highly sensitive hydrophones and filtering technology in the amplifier, technicians can stay dry and listen for leaks due to cracks or separations in the pool shell and plumbing lines.

Ruling out false positives

Listening to suspect areas before using voltage to test for tears and pinholes allows the user to rule out spots that can potentially show a ‘false positive’ reading when electricity is applied. This usually occurs where a positive ground is detected, but the area is not an actual leak. Electricity, even at low voltage, looks to find a ground where the body of water is touching the earth, dirt, or concrete behind the vinyl liner. This ground also occurs where the water touches metal. These areas, typically known to show as false positives, may include any type of metal, such as a screw that holds a light cover to a flange or a drain cover to its pot. Even ladders that are not removed from the pool can produce a ground and show a false positive reading. By identifying potential false positive areas and first listening to them with hydrophones, the user can rule out such areas before proceeding with the applied voltage.

If a leak occurs in a light niche, it can be heard using a hydrophone as the water is pushed through the area of separation. If it is in the skimmer port or return lines, the hydrophone will hear the sound and alert the technician to the location where a leak is. Later, when voltage is applied, these areas will have already been identified and the technician can focus on suspect areas that have not been confirmed to be leaking.

Devices using square voltage

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Accuracy and equal voltage distribution are increased when devices use square voltage. Devices known to use a straight voltage often require weights and strings to keep the transmitter float centered in the pool for voltage to be equally distributed. This often skews results when voltage is applied to identify a ground. Square voltage devices, however, can be placed anywhere in the body of water while delivering an amplified voltage evenly throughout the vessel to identify the ground posed at the point of a leak or pinhole. The amplified voltage from a square voltage transmitter is as strong across the vessel as it is in the middle and does not need to be centred to produce consistent results.

Probing the liner

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A complete vinyl liner leak detection kit should include a float, a proper ground rod, and voltage transmitter. It should also include probes designed for identifying where a ground appears on both horizontal and vertical planes. The design of these probes will help divert the user from picking up on false positives. When a floor probe is in the pool, the angle of the probe directs the sensitivity toward the floor and reduces the effect of grounds showing from lights and ladders giving the impression of a leak. The same effect occurs when a wall probe is facing a vertical surface. Potential ground sounds from screws in drains are less evident depending on the direction the probe is pointing in.

After the technician has listened with a hydrophone, it is time to begin scanning the vinyl liner with the applied voltage of the leak locator. The user will insert the ground rod into the soil near the pool. If the soil is extremely dry, simply using a hose to wet the area before inserting the rod can ensure better results. Note: Inserting the rod below the surface offers the best results when connected to the transmitter device.

Float

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When a device uses square voltage, the float can be placed anywhere in the pool and will distribute the voltage equally throughout the vessel. It is important to remember the float can serve as a ground source and show a false positive reading. Therefore, the author advises placing the float near an area that has been previously cleared of a leak, such as a pool light, ladder, or skimmer. The square voltage applied from the transmitter is evenly distributed into the pool via the float and is attached to the ground rod, completing its circuit by finding a ground beneath the pool liner. When the voltage reaches a ground, it is discoverable using the probes, which emit a pulsing sound through the receiver that alerts the user to the specific area of the leak. A headphone amplifier allows the user to hear the pulsing sound created by the device when it identifies a leak. As the probe gets closer to the leak, the pulse quickens and increases in volume. The noise can begin as far as a few feet away from the leak. When passing the leak and moving away from it, the sound slows and becomes quieter. This allows a technician to precisely locate the area where water is escaping the liner into the ground. Since the water does not necessarily flow as it would through a pipe or a crack in concrete, using an electric voltage to find where the water meets a ground behind the vinyl liner is the best option to discover the leak. Where water might need to pull with a stronger flow for dye to show being ingested into the area of a leak, an electric voltage will easily show smaller leaking areas where water meets a ground and the leak is found. Should the technician then decide to dive a pool and use dye to test the specific area, this can be performed as a back-up measure to show and mark the location where repairs need to be made; however, this is not mandatory.

Setting up the connection

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While this technique has been described using a ground rod in the soil next to a pool, a vinyl liner may be laid over a concrete shell, or the pool may be located inside a building where dirt is not accessible. There are alternatives for setting up the ground wire in the case of a large indoor concrete patio or when the walls separate the inside pool area from the outside. In this case, for setting up the connection without using the actual ground rod, the connecting wire can be applied to anything grounded in the pool area, such as a light pole or metal conduit, which goes into the ground from inside the pool environment. Conduit can often be painted over—sometimes with several layers of paint. The thickness of the coating can hinder the transmitter’s ability to find a ground. It is recommended to attach to a clean metal area with ground wire or to remove a small section of the paint to get a clean connection between the wire connector and the metal. This can greatly enhance the performance of the unit.

Conclusion

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When choosing the right vinyl liner leak detection kit, it is recommended to choose the most modern technology. Using square voltage, and obtaining a kit with advanced listening tools such as hydrophones and phantom-powered listening devices will bypass hindrances known to affect older equipment types. Also, it is recommended to buy a kit where each device is built by the same manufacturer to ensure the pieces work in conjunction with one another.

Water loss in a pool can turn out to be an expensive problem and vinyl-lined pools are no exception. That said, customers will trust a technician who is experienced and has proper equipment. Therefore, service techs should be familiar with all aspects of liner leaks and cover the bases with a complete leak detection kit.

Joe Dolan is the director of communications and marketing for LeakTronics. He has represented a series of service providers and manufacturers in multiple disciplines and directs a wide level of display and communication directly to consumers. With a broad understanding of the value and ease of leak detection as a business model using the modern technical designs of LeakTronics equipment, Dolan helps contractors better serve their communities and customers. He can be reached via e-mail at joe@leaktronics.com.

[9]Darren Merlob is the founder of LeakTronics, a manufacturer and distributor of leak detection equipment in Canoga Park, Calif. He has been in the industry for nearly 30 years and has experience in pool renovation as well as leak detection and repair services. He can be reached via e-mail at info@leaktronics.com.         

 

Source URL: https://www.poolspamarketing.com/trade/features/non-invasive-leak-detection-techniques-how-service-techs-can-identify-leaks-in-vinyl-lined-pools-and-rule-out-false-positives/

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