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Listening For Plumbing Leaks With A Hydrophone

Even if you’ve made a good leak noise and are using your electronic listening device filters correctly to pinpoint the location of a plumbing leak using a deck microphone, you may want to use your hydrophone attachment from within the pool to get an additional angle on these plumbing leaks. If the leaking pipe is close to the pool wall, or in a main drain line under the pool, the bubbling noise of air escaping from the pressurized pipe can be heard with your hydrophone through the pool wall. Using a hydrophone is a great way to double check or verify the location you identified from pool deck or help hone in on a leak noise that spans a large area.

Leak technician using hydrophone to listen through pool wall

Because you’re often able to get so close to the leak when listening through the pool wall, the digital readout on your Fisher electronic listening device is especially helpful for this use. There will typically be a more definite high point in the volume readout, which can be more accurate than just relying on your ears to determine the loudest place.

Based on our experience, this method of using a hydrophone for pipe leaks has proven to be much more effective than listening for problems from inside the line.  Trying to get the hydrophone into pipes past T’s and elbows is time consuming (if not impossible), and unpressurized leaks may not even make a perceptible noise.  Knowing how to use the right tool at the right time is an important way to make your leak detection jobs efficient and accurate.

Tagged , | Posted in Education, Tips & Tricks

Case Study: New Pool, Big Leak

Type of Pool:

Vinyl Liner

Equipment Used:

Leakalyzer, LeakTrac, Dye Tester Cones, Pressure Testing Equipment, Electronic Listening Device, Hydrophone, Tube Level

Situation:

We were called to examine a new build that was losing 4” of water per day. It hadn’t been leaking for the first four days that it was filled but recently started rapidly losing water. When we arrived to the pool the water level was down below the skimmers, but the skimmer bowls were still full of water – indicating that those lines were not leaking.

Solution:

Suspecting that the problem was in a plumbing line, we did a quick dye test of the returns and cleaner line with the dye testing cones, but they also were not drawing water. Our Leakalyzer test had been running during these initial observations, and indicated a loss of 3.5 inches per day. A quick scan with the LeakTrac showed no leaks in the liner, so it was time to dive down to the main drain. A dye test with the dye testing cones showed that line was the source of our water loss.

We then plugged the main drain lines while we were diving and ran a pressure test from the equipment back to the pool. The water pressure test confirmed the line was leaking, so we then started inducing air for sonic location. It took a while for the air to reach the leak, indicating that the leak wasn’t close to the equipment where the air was being induced. So, we used a hydrophone attached to our XLT30H listening device to start listening along the main drain lines where they ran close to the shell of the pool. We could hear the loud bubbling/gurgling noise of air escaping into water saturated soil near the base of the wall in the middle of the deep end.

Since the main drains were plugged we ran another Leakalyzer test to verify that the rest of the pool shell was not losing water and the main drain line was the only issue.

A main drain leak at the base of the wall is not a repair anyone wants to make, so to verify the sonic leak location we used a tube level. We attached a clear plastic tube to the end of a standard open plug in the main drain. Now, instead the leak draining water from the pool it drained the water in the tube. The tube leaked down to the level of the leak and then stopped. We colored the water in the tube with Leakmaster Fluorescent Dye to be able to clearly see the water level. The water level stopped right at the level that we had identified with the hydrophone.

The crew dug up the leaking plumbing line and found a stake had been driven through the pipe!?!

Highlights:

  1. A hydrophone with digital sound graph is helpful when listening for main drain plumbing leaks through the shell of the pool.
  2. The Leakalyzer helps verify the rest of pool isn’t leaking while pressure testing and pinpointing leaks in plumbing.
  3. A simple tube level can help verify the depth of the leak before digging. Be creative with the materials you have on hand!
Tagged , , , , , | Posted in Case Studies

Case Study: A Job Done Right Pays Off

Type of Pool:

Concrete – Commercial (Apartment Complex)

Equipment Used:

Leakalyzer, Pressure Testing Equipment, Hydrophone, Dye, Dry Suit, Super Snorkel

Situation:

After opening the pool for the summer the customer noticed significant water loss and gave us a call. When we arrived to the job the Leakalyzer reported nearly 6” of water loss per day.

Solution:

The first two leaks were found right away while we were gathering information. One was clearly visible while we were inspecting a return fitting and the other was found around an equalizer line while we were scanning the pool with a hydrophone. We were able to repair both leaks with Leakmaster Pool Repair Putty.

After the initial leaks were repaired a new Leakalyzer test reported 2.35” of water loss per day. We used dye to find two more leaks – one at another return fitting and one at the tile line.

Once these leaks were repaired the Leakalyzer was still reporting a loss of 1.84” per day. So far we had found and repaired four leaks but were still losing a significant amount of water. We ran a quick pressure test to eliminate the plumbing as the source of the remaining water loss.

Finally a crack in the tile line deeper down in the pool was found and fixed getting us to a no water loss test. Five leaks found, five leaks repaired. Between the multiple Leakalyzer tests, pressure tests, electronic microphone use, extensive dye testing and even diving in freezing spring water this job was more work than most. Once it was all said and done we felt good that we didn’t just solve one of their problems and move along. The property manager was thankful and eager to get us set up as a vendor for all their properties. They even mentioned that we’d done more than other companies had ever done.

Highlights:

  1. Large leaks in concrete pools can be found with a hydrophone, but it may not pick up smaller leaks.
  2. Using the Leakalyzer throughout the job meant we were there longer finding additional leaks, but it saved us from a costly callback.
  3. Extra effort and a job well done gets noticed and helps drive future business.
Tagged , , , , | Posted in Case Studies

Case Study: Eliminating Misleading Leak Sounds

Type of Pool:

Vinyl Liner

Equipment Used:

Leakalyzer, Pressure Testing Equipment, XLT30H, Hydrophone,  Dye

Situation:

Customer reported that the pool was leaking 1-2 inches per day and that a new liner was installed recently. When we arrived, the pool level had already dropped below the skimmers and returns.

Solution:

We ran a pump on and pump off test with the Leakalyzer and found the pool was losing slightly more water with the pump off. This indicated that we should suspect suction side plumbing. Since the pool water level was already below the skimmers we dove down to check the main drains. A dye test confirmed that the main drain line was drawing dye from both of the two main drains.

We set up our pressure testing equipment to start pinpointing the location of the leak and ran a quick pressure test with water first to confirm that what the dye was showing was accurate. Once we started inducing air and purged all the water from the line we were able to hear a good leak noise in two spots with the Hydrophone (attached to the XLT30H). The first noise was right at one of the main drain bowls and the other was in a corner of the pool. While we had the main drain lines plugged we also ran another Leakalyzer test, which verified the water loss had stopped in the pool so there was no need to run a LeakTrac on the liner or dye test the fittings, skimmers, etc.

In order to determine which noise we were hearing was actually the leak, we slid an inflatable plug 8’ into the line from the main drain bowl and re-pressure tested. The pressure test still failed, so we knew the leak had to be farther than 8’ away from the main drain bowl. With this information we decided that the place we heard noise in the corner of the pool was the leak location. Another confirming factor was that while we were inducing air, there would occasionally be a bubble that came up behind the liner to the surface of the pool. Before leaving we also ran pressure tests on skimmer and returns to verify the rest of the plumbing was good.

Learnings:

  1. Pressure testing helped us identify actual problem when the  noise was heard in multiple locations.
  2. Leakalyzer verified that pool shell was leak free, saving us time during the isolation phase.
Tagged , , , , | Posted in Case Studies

Case Study: Persistence Pays Off

 

Type of Pool:

Gunite Spa/Pool

Equipment Used:

Leakalyzer, XLT30H, Hydrophone ,Dye, Ridgid Inspection Scope,  Ridgid Micro Drain Reel, Pressure Testing Equipment, Dye Testing Cones

Situation:

The customer called because their pool would leak down to the tile line and stop, so they wanted us to locate the leak and asses the tile line to determine if a full renovation was needed. When we got to the pool the water level was filled to the normal level as we requested, but the customer pointed out where it would typically leak down to which was an inch below the skimmer, but a couple inches above the jets. It seemed as though we were in for a quick tile line crack location and putty repair.

Solution:

We ran a Leakalyzer test to get a better understanding of how fast the pool was losing water and while doing so started listening with a hydrophone to the suspected tile line. A quick trip around the pool with the hydrophone didn’t uncover any suspect areas. We moved on to dye testing because sometimes small leaks don’t make enough noise for the hydrophone. After dye testing the whole tile line we were able to confirm that there were no leaks in the shell of the pool at the level where the water drained down to. It turns out this job was going to be a little more complicated than we thought!

We checked our ongoing Leakalyzer test which was showing a current rate of over 20” per day of water loss (small pool, big leak). To do a quick check of the plumbing lines we used the Dye Tester Cones and learned that the jet returns drew dye like crazy. Because the water level stopped higher than the jets we began to suspect the blower line instead of the jet return line. A pressure test confirmed the suspected line was leaking as we couldn’t even build any pressure. A Leakalyzer test with the jet returns plugged confirmed the rest of the pool was not losing water, so we knew we could be done with any further testing in the shell of the pool.

Since the equipment pad was positioned lower than the pool, in order to induce air from the high side of the plumbing we had to use one of the jet returns. When we started listening with the XLT30H there was a loud noise right above where we were inducing pressure that actually seemed to echo throughout the pool. There were two places that seemed louder and more distinct than the other areas though: the jet fitting and a place where the pipes presumably ran underneath the pool. We deduced that even though we were inducing from the high side of the plumbing, since the leak was in the blower line the air had to travel through remaining water in the jet line, creating some of and perhaps all the noise we were hearing. To confirm this suspicion, we switched and induced pressure from the other side of the plumbing. After this switch the sound in those two locations went silent. This confirmed we were hearing the sound of air traveling through remaining water in the pipe and not air escaping out of the leak into water saturated soil.

The lack of noise around the pool forced us to look closer to the equipment which would mean that the leak had to be well below where the water level stopped.  It turned out there was a Hartford Loop for the blower line, but it wasn’t high enough and thus didn’t stop water from draining back through until the water level reached the familiar point on the tile.  We suspect someone made a modification to the blower plumbing at some point for aesthetic reasons and buried the loop without understanding its purpose.

Building enough pressure for a quick sonic location was difficult and since we had easy access to the flexpipe  we used a Ridgid Micro Drain Scope and a line locator to pinpoint the exact location. About 15 feet in we saw what appeared to be a cracked pipe due to freeze damage.

To verify the crack we saw was our leak, water was induced into the blower line from the high side of the plumbing and we pulled that camera back towards the low side of the plumbing watching for the water flow to stop.  Sure enough the water was flowing into this crack.  The crack was dye tested with extension tubing from Anderson Manufacturing affixed to the end of the camera. The dye was drawn into the crack a well. The crack was about 8’ long and on both sides of the pipe – so no wonder we couldn’t build pressure!

Learnings:

  1. Just because water stops at the tile line doesn’t mean it’s the tile line that’s leaking!
  2. Inducing pressure from both ends of plumbing can be a way to verify if you’re hearing a leak noise vs air traveling through water in pipe. If noise is only audible when you induce from one end it may be standing water in the pipe not air escaping into water saturated soil.
  3. Dye Tester Extension Tubing can be taped to inspection cameras for leak verification or location.
  4. Persistence paid off, but this one was a bit misleading and ended up being time consuming. Some leaks are more tricky than others!

 

Tagged , , , , | Posted in Education

Hydrophone Tip: Attach to Pool Pole for Easy Placement

Hydrophones can be a useful too for quickly identifying if areas of a pool may be leaking without getting in the water, but they can be difficult to position in order to hear the proper noises. Some of this frustration can be avoided by attaching the hydrophone to the end of a pool pool. You can then position the microphone exactly where you want to listen instead of tossing and dragging it along the pool floor.

A pool pole also isn’t your only option. One of our customers even attached his hydrophone to a telescoping fishing pole for a more permanent solution that was easy to store and didn’t have to be removed when otherwise using the pool pole. Creativity typically pays off when it comes to leak detecting!

Tagged | Posted in Tips & Tricks

Case Study: Thin Ground Probes are Necessary for Deep Leaks

Type of Pool:

Vinyl / In-ground

Equipment Used:

Leakalyzer, XLT30H Bigfoot and Ground Probes, Hydrophone, Pressure Testing Kit, Dye

Situation

We received a call about a pool that had just had a new liner installed, but was still losing lots of water. The customer suspected the water loss was in the main drain line. When we arrived to the pool the Leakalyzer confirmed the reported water loss.

Solution

The main drain lines were plumbed separately up to the equipment, so we put an open plug in each of the main drains to see if they would draw dye. One line did, but the other did not. To confirm, we pressure tested the line that drew dye with water and it failed. In order to pinpoint the exact location of the leak, we then induced air into the line and began to listen with the hydrophone for a leak under the pool, but didn’t hear any significant noises. We then switched to using the Bigfoot microphone with the XLT30H to listen through the concrete around the pool and still didn’t hear anything that indicated the leak location. Only when we started using the XLT30H ground probes in the soil between the pool deck and the equipment were we able to get close enough to the leak to pick up a great noise and find the exact location of the leak.

Learnings

  1. Thin ground probe rods included with the XLT30H make it possible to get the probe deep into ground to absorb leak sound vibrations.
  2. Turning air pressure off and back on once hearing the leak location confirms the noise is the one we are making.
Tagged , , , , | Posted in Case Studies

What makes a top notch listening device?

When it comes those tough underground plumbing leaks, electronic listening devices are the backbone of the leak detection industry.   While there are other methods the most reliable and consistent method is to make a noise at the leak with pressurized air escaping into water saturated soil, then listen for where the noise is coming from.  This noise can sometimes be picked up by just an open ear but often a listening device is needed to help amplify the sound and filter out other noises to focus in on leak sound and pinpoint location.

Choosing the right listening device for your company is an important decision. When researching a product purchase, similar to listening for a leak, there can be a lot of “noise” to sift through.  Here at Anderson Manufacturing we have combined research and testing with the experience of hundreds of pool leak detection professionals to find and keep the best option for a swimming pool leak listening device.

While there are many factors to think about such as cost, dependability and service after the sale. There are also some more technical criteria to consider when looking at purchasing a swimming pool leak listening device.   Since listening devices range from your standard geophones to sophisticated technology here are some tips for what criteria to look at.

Important criteria to consider when comparing listening devices:

Sensitivity – how well the device amplifies sounds from the transmitting material 

Frequency Range – how broadly the device can hear all the sounds created by a leak

Filtering – how effectively the device can filter out background noise enabling  you to focus on a leak sound

The Bigfoot microphone for the XLT30H reduces outside noise interference.
The Bigfoot microphone for the XLT30H reduces outside noise interference.
Sensitivity

The standard ground microphones that come with Fisher’s XLT17 and the XLT30H listening devices, use piezoelectric microphones because these are known to be the best type of microphone to use in situations where sounds are being picked up from liquids or solids.  Virtually every company that makes serious equipment for locating underground plumbing leaks for municipal work incorporates piezoelectric technology. Accessing the technological knowledge of those who have experience in this area is one reason we have chosen to work with Fisher and utilize their products.  This type of equipment requires more specialized expertise than standard microphone amplification (that used for music/voice etc.).

In practice you will find that sensitivity by itself however is not the only important performance criteria.  Most any device will be able to amplify a sound to the point that it will hurt your ears.  What’s more important is hearing the right sound and distinguishing it from background noise.  That’s where the other two important criteria come into play.

 

Frequency Range

Both pressurized underground plumbing leaks and static shell leaks in the pool make noises in a wide range of frequencies depending on a variety of conditions.   We like to think of the sounds a leak makes in the same way we do instruments in an orchestra.  You want to be able to hear everything from the shrillest piccolo to the deepest tuba.  Although every leak is different, as general rule underground plumbing leaks make sounds in the lower frequency ranges while static leaks in the shell of the pool are in the higher range.  If your listening device doesn’t pick up sounds at the top or bottom of this range you will be missing the fullness of the sound a leak makes or you may miss it altogether.  Both the Fisher XLT17 and XLT30H pick up sounds in a frequency range of 20Hz to 6000Hz.  In addition, the XLT30H includes a switch that enables the unit to work effectively both when sounds are in the low range (for underground leaks picked up by the Bigfoot microphone) and the higher ranges (for underwater leaks picked up by the hydrophone).

 

Filtering Capability

The final performance criteria, and what we consider to be the most important for swimming pool applications, is an area where Fisher devices particularly shine over all others we have researched.  A listening devices filter allows you to specifically highlight (or eliminate) a specific range of sounds.  Consider for instance that we only wanted to hear the violins in the orchestra of leak sounds we imagined above.  Filtering is important because the devices are so sensitive that we will likely hear other sounds around the pool (it always seems as though the next door neighbor want to mow their grass when you’re trying to find a leak!).  The filter helps us zero in on the leak sound without being distracted by the background noise.  Additionally, different ranges of sound behave differently underground or underwater.  Low frequency sounds travel much further than high frequency sounds.  By selecting high frequency sounds once a leak sound has been identified the frequency filter can help in pinpointing leaks to a small area.

 

Fisher devices provide a wide range of filtering options to address most any scenario. The Band Pass filter allows selection of a narrow band of frequency anywhere in the range of sound.  The Hi Pass filter focuses high frequency sounds providing adjustment of the low end of this range.  The Low Pass filter does the opposite – focusing on the low end and providing an adjustable high end..  The XLT30H also includes a Notch Filter that allows the elimination of a specific frequency range (for instance to minimize the “hum” of a nearby air-conditioner) and can be used at the same time as the other filters.

 

Another noise minimizing feature available on Fisher devices is especially important when the unit is used for listening to pipes in the ground.  The Bigfoot muffler utilized by Fisher to minimize outside noises transmitted through the air is the best we’ve seen.  This rubber boot deadens outside noises preventing them from reaching the sensitive piezoelectric microphone which makes direct contact with the pool deck or ground through a heavy aluminum foot.

 

Conclusion

Ultimately, we are convinced, that Fisher Listening Devices as sold by Anderson Manufacturing Co. are the most technologically advanced, well rounded tool for all types of swimming pool acoustical leak location   They have been continually improved through the years and currently represent the best package for addressing pool leak problems in both the plumbing and shell.  We back our belief with the evidence of thousands of successful customers and a satisfaction guarantee that promises your money back if you are not satisfied with their performance.

If you have made it this far through this you have taken in a lot of information, hopefully it has been helpful in making decisions that will affect your leak detection success.  Remember you can always call and talk through the buying process or for technical help regarding a leak or leak detection equipment. Thanks for reading!

 

Tagged , | Posted in Education

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