The 6 Best Ultrasonic Leak Detectors
Updated by · How we research
Built for HVAC, compressed air and seals, six ultrasonic leak detectors compared by range, accessories and specs. The Inficon Whisper leads, now as a kit. When users buy our independently chosen editorial picks, we may earn commissions to help fund the Wiki.
An ultrasonic leak detector hears what a mechanical stethoscope can't: the hiss, around 40 kilohertz, that gas makes as it escapes through a small hole, which it turns into sound you can hear. HVAC techs, plant maintenance crews and mechanics use them on refrigerant, compressed-air and vacuum lines. Most figures here come from makers or sellers.
Editor's Notes
October 19, 2026, by Ezvid Wiki Admin:
Certified for the newer, mildly flammable refrigerants, the Inficon Whisper takes the top spot, now as the kit with a transmitter and a contact probe. It's also the detector readers search for by name. Much of the 2021 list was gone. The Robinair 16455 TruTrack and the Bacharach Tru Pointe are no longer available, and Amprobe replaced its ULD-300 with the Amprobe ULD-405, which is new here. We dropped the Allsun EM410 because it's a mechanical stethoscope that hears ordinary sound, not ultrasound. The Allsun EM2280 went too, since the allsun Pro covers the same jobs with more accessories.
The AccuTrak stays, now as the AccuTrak VPE Professional kit. A gooseneck version is still sold if you want to bend the sensor around a coil.
The FOTRIC TD2e is a new idea for this list: a camera that shows you where the sound is coming from.
Evidence is thin in this category. We found no independent side-by-side tests, so we leaned on maker spec sheets, HVAC trade coverage and recall checks, and each entry says when a figure comes only from the seller.
March 02, 2021:
I’ve added some more affordable models like the Allsun EM2280 and EM410, as well as one more to the higher end of our list in the Superior Signal AccuTrak Kit. It may seem like there’s a large price gap between the likes of higher end models like Bacharach Tru Pointe and Robinair 16455 TruTrack with the rest, you’ve got to remember that these options are both more sensitive to a wide variety of leaks, and are prone to less interference. As is expected, this discrepancy in quality between high-end and budget models can make a huge difference in the professional field where experts may be on multiple jobs a day and the accuracy with which they detect leaks is paramount to their employability.
High-end professional tools always cost quite a bit more to engineer, and you’ll see the same sort of discrepancies in refrigerant leak detectors too. Note that, unlike refrigerant leak detectors, ultrasonic leak detectors do not pick up refrigerants or other gases; rather, they detect the high-pitched sound of gas escaping from a system. As such, their advantage is that they can be used to detect a wider variety of leaks, but are also prone to sound interference in a way that refrigerant leak detectors aren’t.
April 08, 2019:
While the selections on this list are all quality options, that doesn't necessarily mean that they're all equally suitable for whatever task you have at hand. For example, the Robinair 16455 TruTrack is ideal for HVAC technicians, whereas mechanics in busy garages may prefer the Amprobe ULD-300.
Some models come with their own headsets, like the Inficon Whisper, while others require you to purchase your own. Which one is preferable for you is a decision we can't make; some people will want to upgrade the basic models that come with the devices, while others will be more than happy to deal with a little less comfort and inferior sound quality in exchange for more money in their pockets. It's completely up to you, so long as you can still hear clearly, whichever one you choose.
Special Honors
UE Systems Ultraprobe 100 UE Systems builds the Ultraprobe line of ultrasonic inspection instruments used in plant maintenance programs, and it's a good place to learn ultrasound inspection beyond leaks. Its entry model, the Ultraprobe 100, is a handheld leak and steam-trap checker with an eight-step sensitivity dial and an LED bar graph that reads in decibels, powered by a single 9-volt battery. It's sold through the maker and its distributors rather than general retail sites, and it costs more than most handheld detectors. uesystems.com
How Ultrasonic Detection Works, And Where It Struggles
Gas forced through a tiny hole, or pulled into a vacuum, churns the air around the opening.
Gas forced through a tiny hole, or pulled into a vacuum, churns the air around the opening. That turbulence gives off ultrasound, mostly in the 36 to 44 kilohertz band, far above human hearing. A detector uses a microphone tuned to that band and shifts what it hears down to an audible hiss in the headphones, plus a bar graph or a number on a screen. The Inficon Whisper listens at about 40.5 kilohertz, while the Amprobe ULD-405 covers 20 to 90 kilohertz.
Because it listens instead of sniffing, an ultrasonic tool works with any gas: refrigerant, nitrogen, compressed air, steam or a vacuum. It also works on a system that's been emptied and pressurized with dry nitrogen. A field video from HVAC School shows a tech confirming a coil leak this way, hearing nitrogen rather than refrigerant.
It has limits. Wind and machinery noise make faint leaks hard to hear, and soap bubbles from an earlier check can plug a leak so it goes quiet, according to HVAC School's guide to electronic detectors. Cranking the sensitivity all the way up isn't always better; turn it down as you close in. An HVAC School podcast adds that ultrasonic works well right after shutdown, while pressures equalize, and that most misses come from inexperience rather than the tool. In a later HVAC School video, the presenter says ultrasonic worked better than he first thought after several detectors were compared side by side.
Ultrasonic, Heated Diode Or Infrared: Picking A Tool For The Job
Refrigerant sniffers, with heated-diode or infrared sensors, pull in air and react to the gas itself. They can be very sensitive to small refrigerant leaks, but heated-diode sensors wear out and can react to other chemicals, and infrared sensors need slow, steady movement (HVAC School; an Inficon interview covers the trade-offs). An ultrasonic detector has no sensor to wear out and doesn't care what the gas is, but it takes practice. Many HVAC techs carry both and use one to confirm the other.
Match the tool to the work. For refrigerant and gas lines in noisy mechanical rooms, look for adjustable sensitivity, a focusing tip, and closed-back headphones. Superior Signal's AccuTrak VPE is sold in several kits, from a basic detector and headset to gooseneck and hard-hat versions. For compressed-air audits, range matters, so a parabola or long waveguide helps. For door, window, hatch and vehicle seals, you need a transmitter: it fills the closed space with ultrasound so the detector can find where it gets out.
Acoustic cameras take a different approach. They use dozens of microphones to place the sound on a camera image, which speeds up surveys of long pipe runs. Industrial models, such as Fluke's ii905, cost about as much as a used car, while a handheld wand can find the same leaks if you have the time to sweep.
Safety, Refrigerant Rules And Care
An ultrasonic leak detector isn't a gas alarm. It can't warn you about natural gas, propane, carbon monoxide or low oxygen, so use a proper gas detector around fuel lines and appliances. If you work on systems with mildly flammable A2L refrigerants such as R-32 or R-454B, check that any electronic tool you bring is rated for it; Inficon's datasheet lists the Whisper as A2L certified.
Pressure-test refrigeration lines with dry nitrogen, never with shop compressed air, and never above the system's rated test pressure. Over-pressurizing can create the very leaks you're hunting (HVAC School). When you use a detector to find electrical arcing or corona, keep your body and the tool clear of live parts and follow your site's lockout rules. Set the headphone volume just above the background noise.
Buying a detector needs no license, but handling refrigerant does: EPA Section 608 certification in the U.S. The EPA also sets leak-rate limits for appliances with 50 pounds or more of ozone-depleting refrigerant, at 10% a year for comfort cooling, 20% for commercial refrigeration and 30% for industrial process systems, with 30 days to repair. For care, take the batteries out before storage, keep the sensor tip clean and dry, and read the manual's notes on sensitivity settings before your first job.
How we researched this
We compared 16 ultrasonic leak detectors, acoustic cameras and look-alike tools, and studied six in depth. We read makers' spec pages and datasheets where they exist (Inficon, Superior Signal, Amprobe and UE Systems), trade coverage from HVAC School, the EPA's refrigerant leak-repair rules and the sellers' own listings, and we searched the U.S. Consumer Product Safety Commission's recall database for each brand. No leak-detector recalls turned up, though the search failed for some smaller brands. We found no independent side-by-side tests.
Sources (12)
- Inficon: Whisper ultrasonic leak detector
- Inficon: Whisper datasheet
- Superior Signal: AccuTrak VPE
- Amprobe: ULD-405
- UE Systems: Ultraprobe 100
- HVAC School: Callback prevention, electronic leak detection
- HVAC School podcast: Is ultrasonic leak detection best?
- HVAC School video: finding a leak with an AccuTrak ultrasonic
- HVAC School podcast: Understanding leak detectors with Inficon
- HVAC School video: I changed my mind about ultrasonic leak detection
- U.S. EPA: Stationary refrigeration leak repair requirements
- U.S. CPSC: SaferProducts.gov
Frequently asked questions
What does an ultrasonic leak detector actually detect?
It hears the high-frequency hiss, roughly 36 to 44 kilohertz, that gas makes as it rushes through a small opening. It doesn't sense the gas itself, so it works with refrigerant, nitrogen, compressed air, steam or a vacuum.
Is an ultrasonic leak detector good for HVAC refrigerant leaks?
Yes, if the system is under pressure so gas is moving through the leak. It also works on a system pressurized with nitrogen. Very small leaks in windy or noisy spots are hard to hear, so many techs pair it with a heated-diode or infrared sniffer.
Can an ultrasonic leak detector find water leaks?
Generally no. These tools are made for gas and vacuum leaks, and several sellers say outright that theirs isn't meant for water pipes, pools or tires. For plumbing, look at moisture meters or a plumber's acoustic leak locator.
Do I need a transmitter?
Only for spaces with no pressure in them, like a car cabin, a cooler lid or a door seal. You put the transmitter inside, close it up, and listen outside for where the sound escapes. For pressurized lines you don't need one.
Is the Inficon Whisper worth it?
On paper it's the best-documented wand here: a laser pointer, about 165 hours on two D cells, A2L certification and a two-year replacement warranty. We found no independent lab test of it. If you don't need a transmitter or contact probe, the bare wand costs much less than the kit.
Do I need a license to use one?
No license is needed to buy or use the detector. In the U.S., anyone who opens a refrigerant circuit or handles refrigerant needs EPA Section 608 certification.
