Wohler UL 23 Ultrasonic Leak Detector with Ultrasonic Transmitter User Manual

: June 4, 2024
: WOHLER

Table of Contents

UL 23 Ultrasonic Leak Detector
1. Specifications
- 1.1. Important information
- 1.2. Application
2. Principle of Operation
3. Operation
- 3.1. Operational Elements
- 3.2. Operation
- 3.3. Background Noise
  - 3.3.1. Methods of reducing background noise interference
- 3.4. Tipps on use
4. Applications
- 4.1. Systems under pressure
- 4.2. Unpressurized Systems
- 4.3. Machines and components
5. Troubleshooting Guide
6. Battery installation
7. Care and maintenance
8. Calibration
9. Accessories, options
10. Ultrasonic sound generator US 23
- 10.1. Operational elements
11. Technical Data
- 11.1. Battery installation
12. Care and maintenance
13. Headset
14. Touchprobe
15. EG – Conformity Statement
16. Guarantee and Service
- 16.1. Guarantee
- 16.2. Service
- 16.3. Information on disposal
- Points of sale and service
References
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UL 23 Ultrasonic Leak Detector

with Ultrasonic sound Generator US 23

The Measure of Technology

Wöhler UL 23 / US 23

1. Specifications

1.1. Important information

– Carefully study and observe all items of these operating instructions before commissioning the unit.
– In principle, the Wöhler UL 23 and US 23 Ultrasonic Leak Detection should only be used by skilled personnel for its intended purpose and within the specified range of data. Any liability or warranty for results established or for defects caused when using the unit is excluded by all means.
– Be careful, and use common sense around electrical currents! Use the plastic waveguide, and keep at a safe distance!
– Warning: Ultrasonic detectors will not indicate a leak if there is no turbulent flow producing sound when you check it. If you suspect a toxic gas, natural gas or other combustible gas leak, and do not detect it with the UL 23, do not assume that it does not exist as it may be turbulent. Use another method as verification that there is no leaking gas present.

1.2. Application

The UL 23 Ultrasonic Leak Detection is a non-invasive leak detector that is capable of detecting both pressure and vacuum leaks at e.g.:
– gas conduits
– supplies of portable water
– refrigerating sets of air conditioning installations
– LNG-tankers
– pneumatic systems
– hydraulic systems
– vacuum systems
– electrical systems: switches, relays and other contacts
The Ultrasonic sound generator US 23 is used to detect leaks in enclosures which are not under pressure. It is ideal for the leak detection at
– buildings: doors, windows and other leakages (support of the leak detection with the BlowerCheck BC 21)
– automotives: panes, doors etc
– containers
– freezers

As the device is able to detect leaks in different types of medium (gas, liquid), there is a great number of different applications, especially in the sectors heating, air-conditioning, buildings. So the UL 23 is an effective and cost saving device that helps the workman and the ingenieur to resolve many leakage-problems.

2. Principle of Operation

A leak is any unwanted flow of a substance out of a system, or in a vacuum into the system. Friction in flow generates sound, water in pipes creates sound as well as air out of a tire. The sound we can hear is less than a third of the total sprectrum of frequencies generated. The sound in small leaks is mostly ultrasonic. Humans cannot hear this because it is above the human hearing range. In order for a leak to generate ultrasound, the flow through the leak path must be turbulent. For this to happen the velocity that a gas is moving through the leak point must be high in relation to the orifice. The UL 23 receives the ultrasonic sound that escapes from a leak point, processes it, and displays its strength. The larger the leak, the higher the indication. In addition to the display, it produces an audio reproduction of the leak sound. The intensity of the audio will change proportionally to the display.

The principle of operation of the UL 23 is based on the turbulent flow of fluids and gases, turbulent flow has a high content of ultrasound. This is sound which is above the human hearing range, but can be heard with the UL 23, and traced to its source. Imagine air leaking from a tire. Because this is such a large leak, your ear can detect this sound, however your ear hears only about 1/3 of the actual spectrum of sound which exists. The sound of small leaks is mostly ultrasonic so that your ear cannot detect it.

It is important to remember this example: A piece of straight tubing connected to a gas supply and left free to exhaust into the atmosphere will not generate sound, if the volume of gas through it is such that turbulence does not take place. Yet for that same flow, an opening as small as 0.005 of an inch could generate enough sound to be heard several feet away.

For a leak to happen there must be an opening in the system that carries a gas or fluid. Normally, these openings are not clean smooth holes, but passages through cracks with many jegged edges and internal chambers. Fluid or gas escaping through an orifice like this, is forced into turbulence, random circular-like motions. Inside a tube where a gas may be flowing, the flow is normally laminar which means that a given layer of gas does not mix with layers above it or below it. This condition happens in a straight long tube, when the velocity of the fluid is not high. A gas leak out of a straight and long tube will not generate as much sound as if it were leaking out of a small crack because the flow is not turbulent.

The intensity of sound generated at a leak is a very complex function of the viscosity, the temperature, the speed the fluid is moving, the Raynolds number, the pressure differential across the leak, and the physical dimensions and characteristics of the orifice. This is why it is possible for a smaller leak to generate more sound than a larger one.

The UL 23 detects ultrasound, not refrigerant or the presence of a specific gas. It is not a sniffer. Because of this fact, the UL 23 can function in areas where heavy wind or a concentration of fumes renders other detectors useless.

3. Operation

3.1. Operational Elements

Wohler UL 23 Ultrasonic Leak Detector with Ultrasonic Transmitter
B

Figure 3.1: Operational elements

On/Off-button: hold the ON/OFF button during the operation
LED-display: shows the intensity of the received ultrasonic signal
Sensitivity adjustment: upper position corresponds to full sensitivity
Headphone-jack

3.2. Operation

To use the system, plug the headphone into the jack located on the right side of the instrument. Slide the sensitivity adjustment all the way forward, towards the sensor. The UL 23 is now set at full sensitivity. Depress and hold the ,,ON/OFF” button to turn the instrument on. The button does not require much pressure. You can use your left thumb to hold this button, and your left index finger to adjust the sensitivity level. Always start at full sensitivity, then if necessary, gradually reduce the sensitivity to reduce background noise. Note, once the ,,ON/OFF” button is released, the power is turned off. This will conserve battery power.

The UL 23 is capable of hearing leaks from over forty feet away, but it is best to hold the instrument as close to the test area as safely possible. Check around fittings and piping using a zigzag motion, carefully covering all suspected areas. If there is no ultrasonic sound present, the display should not have any lights on. When an ultrasonic signal generated from a leak is detected, it will be indicated by an increase in the LED meter, and a rushing sound will be hard in the headset. This sound will become more intense, and the meter reading will increase as the instrument is drawn closer to the leak point.

If there is noise in the area and the display is at maximum, reduce the sensitivity until the lights disappear. The display reading is only for relative measurements (comparisons). Two lights versus ten can mean two things. Either you are far from a given leak, or the leak is smaller than the one that produces ten lights. Use the sound intensity in the headset and the varying lights to guide you toward the leak point. Reducing the sensitivity as you approach the leak will verify that you are on the right path since the indications will increase in the direction of the leak.

3.3. Background Noise

The UL 23 detects a narrow band of ultrasonic sound, therefore although there may appear to be overwhelming background noise, the sound may not be within the detection range of the instrument. Notice that you can yell directly into the sensor and your voice will not be translated in the headset.

The UL 23’s patented circuitry is capable of reproducing the sound signature of the signal it detects. This means that the sound you hear is closely related to the actual sound. It is an actual translation, not an electronically synthesized tone, or ,,beep”.

Leaks sound like a ,,hiss” or rushing sound, while compressors ,,chatter” a rhythmical mechanical pattern. Fans should not produce wind noise to interfere with leak detection, the fan motor may produce a ,,buzz” or ,,hum” which is a different sound than that of a leak.

Mechanical vibrations sound very different from leak sounds. Shake a set of keys, then take a short quick breath through your nose. Listening to both sounds through the UL 23 is a good example of how the direct translation process of the UL 23 helps you to distinguish the difference between the two signals.

Practice listening to different components of your system, this will help you to identify the sound of a leak from other normal operational sounds.

3.3.1. Methods of reducing background noise interference

Placing the flexible wave guide into the sensor port makes the reception of the UL 23 more directional. This shields the sensor from competing sounds entering from other directions. You can further shield background noise by using something as simpple as a clipboard or piece of foam from inside the carrying case. Your angle of approach also effects results in loud areas. If possible, always aim the instrument away from the source of background noise and toward the suspected leak area.

Reducing the sensitivity suppresses the effect background noise has on the display and headset. This helps make the leak sound more identificable.

The most difficult background sounds come from areas of high turbulence within a pipe. This can be where high velocity flow changes direction, or is restricted such as within a partially closed valve. These situations naturally produce high frequency sound which is very similar to the sound of the leak. Use the standard methods for reducing background noise. If you are still unsuccessful, shut the system down. Although the pressure may be somewhat reduced, it should still be sufficient for leak testing.

3.4. Tipps on use

If you are trying to find a leak in a tight area, use the flex tube in the front of the VPE. You can use any lenght of tube (it is standard 1/4 in.) but remember the sensitivity is slightly reduced the longer you go.
When leak testing, use as much pressure as permissible for the system. Increasing the pressure can double the flow through the same orifice, therefore increasing the ultrasound created by the leak.
If the system permits it, spray distilled water on the suspect area. Before the water runs off, scan with the UL 23. Water on a pressurized leak can increase the amount of sound created.
When searching for vacuum leaks remember, the majority of the sound created by a leak is internal. If the system seals permit, you may need to pressurizes the system with dry nitrogen in order to increase the sound of the leak.

4. Applications

The UL 23 is a very versatile test instrument. Ultrasonic sound is generally produced by friction, arcing, and turbulence. Therefore any pressurized gas, moving machine, or electrical system can be tested. With the optional Ultrasonic Sound Generator you can also find easily leaks in non-invasive enclosures, such as building.

4.1. Systems under pressure

4.1.1. Ductwork

Leaking ducts can be a sinificant source of energy loss. The UL 23 can be used to identify the sound of air leaking from a pressurized duct system.

4.1.2. Refrigerating sets of air conditioning instalations

Especially in areas where heavy wind or a concentration of fumes render other detectors useless, the UL 23 still will function. It does not ,,sniff” the turbulent medium, but it ,,hears” it, independently of the wind.

4.1.3. Pneumatics and Hydraulics

Leaks are quite common in pneumatic systems (controls, hoses, tools, fittings): Listen for the rushing sound of the leak! Large hydraulic leaks are obviously easy to see, but small ones can often be difficult. The UL 23 will allow you to hear these leaks with ease! When testing for hydraulic leaks use the yellow waveguide to protect any fluid from entering the sensor.

4.1.4. Leaks behind walls or under Insulation

These are difficult to find by any method, and are also difficult with UL 23 because the drywall or insulation drastically reduces the amount of sound present on the opposite side. Although the UL 23 was not designed to find theses types of leaks, it has been somewhat successful finding large leaks in these situations.

4.1.5. Electrical Arcing

A jump in electrical current or Arc, will make a popping, frying, or buzzing noise in the ultrasonic range. The AccuTrak can be used to locate electrical failures which are causing a decline in power quality. Use to test circuit breakers, buss bars, relays, corrosion in contacts, or poor insulation.

Warning: Be careful, and use common sense around electrical currents! Use the plastic waveguide, and keep at a safe distance!

4.2. Unpressurized Systems

Leaks at unpressurized systems like buildings, automobiles etc. will be detected with the additional help of the Ultrasonic Sound Generator US 23 (see chapter 8).

The US 23 is used to fill rooms with sound that is above the human hearing range, and cannot be heard. It can penetrate through minute cracks, even ones that are not directly behind the leak point, and exit through it. It can thus trace the path air, or water, will take to cause a leak.

The UL 23 receives the ultrasonic sound that escapes from the leak point, processes it and displays its strength. The bigger the leak is, the higher the volume in the headset.

To test an enclosure, turn the US 23 on and place it on one side of the item to be tested. Close the door, window, etc., or seal the enclosure being tested. Using the UL 23 start from a low sensitivity and check if you can hear any sound. If you can, check the area of interest and note the points where the intensity is high. If you cannot hear any sound, increase the sensitivity and repeat the previous step. The points where the sound is greatest are most likely leaks.

If the sound from the generator is too loud, and seems to be coming from everywhere, you should place the unit in a towel, or use another method to muffle the sound.

Pressing the ,,Mode Select” button will change the output of the generator from continuous tone to ,,Burst Tone”. If the background noise is extremely loud in a particular area, using Burst Tone will make the output of the US 23 much easier to hear.

4.2.1. Buildings

Weatherizing buildings requires finding the points where the weather elements can enter the building.

With the UL 23 and the US 23 the task becomes very simple. Place the US 23 in the room to be leak-tested and turn it on. Go outside with the UL 23 and start a systematic search to find the leaks. Of course you also have the possibility to place the US 23 outside and to check inside with the UL 23.

Start around the perimeters of the doors and windows, using tape and a marker pen to register the volume levels at the locations they are discovered. After you have finished, read the numbers on your tape and try to determine the cause of the problem. Using tape saves you from repeating the checks.

4.2.2. Automobiles

Windshields and trunk seals can be tested by placing the sound generator on the inside of the automobile and testing on the outside. Be sure the area to be tested is dry as the capillary tension in the water may block the passage of sound.

4.2.3. Other Containers

Freezer boxes and refrigerated truck bodies can be tested for tightness like any other enclosure. Depending on the size, it may be necessary to move the US 23 every ten feet inside the trailer to maximize its effectiveness.

4.3. Machines and components

Using the flexible touchprobe (see chapter 8) you can detect bad valves seats and steam traps. Other applications include the detection of friction, lack of lubrication and worn bearings, motors and gears.

Being careful not the cross thread, simply unscrew the existing nose piece and replace with metal probe. Place the tip of the probe on the item being tested with enough force to hold it in place. Be careful around moving equipment.

5. Troubleshooting Guide

Humming sound:
Certain electrical products such as computer terminals emit a high frequency ,,humming” sound. This is not an electrical field interfering with the operation of the UL 23, it is an actual sound that the unit is ,,hearing”. To confirm this place your finger over the sensor hole, and the sound will disappear. In almost all cases, this sound is not severe enough to interfere with leak detection.

Hissing noise:
There is a certain amount of hiss which is normal for ultrasonic detectors. You should expect to hear some hissing, however if it is so loud that you can not hear anything else, it is a problem which deserves attention.
The signal in the head set cuts in and out:

There are two reasons this can happen. First a low battery will cause this problem. Secondly, a bad headset connector can do the same. If you have another headset available, such as that from a portable radio (with a 3,5 mm plug), try it. If you determine that the headset is defective, return it to Superior Signal or your wholesaler for replacement.
Not sure unit is working
Can the unit hear the blink of your eyes? If it can, chances are it is working fine. The leak you are trying to hear may not be turbulent.

6. Battery installation

There is a sliding battery door located on the back of the UL 23.

Turn the unit over so that the controls are facing the floor, and the sensor is facing away from your body.

At the opposite end from the sensors (the end closest to you) there is a sliding panel.

Apply minimal pressure to the center of the panel and slide it towards you exposing the battery compartment.

Install a new 9 volt battery noting the (+) and (-) positions which are indicated on the inner label.

If you plan to store the instrument for an extended period of time, remove the battery.

7. Care and maintenance

The UL 23 can be cleaned with a towel using dish soap and damp cloth. Remove the batteries and close the door before cleaning. Do not allow water to enter the unit, especially the front where the sensor is located. After cleaning, dry the units with a paper towel. The same procedure can be used on the carrying case.

8. Calibration

The UL 23 is designed in a way to minimize the need for regular calibrations. They are constructed with components of very tight tolerances and do not age rapidly.

9. Accessories, options

Ultrasonic leak detector article-no. 3620
Ultrasonic sound generator article-no. 3221
Contact probe article-no. 3622
Flexible wave guide article-no. 3623
Transport case article-no. 7278

10. Ultrasonic sound generator US 23

For the detection of leaks at non-pressurized rooms and enclosures the ultrasonic sound generator US 23 generates ultrasound with 115 dB that cannot be heard (see chapter 3).

10.1. Operational elements

Figure 10.1: Operational elements US 23

On/Off: Switches the advice on/off
Mode-Select: Changes the output of the generator from continuous tone to ,”Burst Tone”.
Mode: shows the selected mode
Battery (green: full batteries, red: low or empty batteries)

11. Technical Data

Frequency Control Precision Crystal Oscillator
Output Frequency 40 kHz (+/-2.5 Hz)
Frequenzy Accuracy +/- 50 parts per million
Precision Voltage Regulator 1% Regulation
Output Intensity 115 db at 30 cm. (nominal)
Dual Mode Output Continuous or Burst Tone
Power 9 Volt Cell
Battery Life (approx.) 70 hrs. continuous, 90 hrs. Burst

11.1. Battery installation

There is a sliding battery door located on the back of the Ultrasonic Sound Generator.

Turn the unit over so that the controls are facing the floor, and the sensor is facing away form your body.

At the opposite end from the sensors (the end closest to you) there is a sliding panel.

Apply minimal pressure to the center of the panel and slide it towards you exposing the battery compartment.

Install a new 9 volt battery noting the (+) and (-) positions which are indicated on the inner label.

If you plan to store the instrument for an extended period of time, remove the battery.

12. Care and maintenance

The Ultrasonic Sound Generator can be cleaned with a towel using dish soap and damp cloth. Remove the batteries and close the door before cleaning. Do not allow water to enter the unit, especially the front where the sensor is located. After cleaning, dry the units with a paper towel. The same procedure can be used on the carrying case.

13. Headset

To use the system, plug the headphone into the jack located on the right side of the instrument. The loudness can be controlled by a sensitivity adjustment which is integrated in the cable.

Figure 13.1 : complete case with headset and contact probe

14. Touchprobe

Ultrasound not only travels through air but solid materials as well. The patent pending contact probe is used to detect sound which is internally generated, see chapter 3.

15. EG – Conformity Statement

For the following product:

UL 23 Ultrasonic Leak Detector
US 23 Ultrasonic Sound Generator

the importeur confirms that it complies with the essential protection requirements of Council Directive 89/336/EEC on the approximation of the laws of the Member States relating to electromagnetic compability.

Assessment of compliance of the product with the requirements relating to electromagnetic compability was based on the following standards:

EN 50082-1/1997 resistance to jamming
EN 50081-1/1993 emission
FCC 15.109: emission

This declaration is based on third party measurements.

Bad Wünnenberg, 10.08.2022

Johannes Lötfering, Geschäftsführer/Managing Director

16. Guarantee and Service

16.1. Guarantee

The guarantee period for the meter is 12 months from the sales date, provided that it is used correctly.
This guarantee does not include the costs for transport and packing material in case of repair. It will expire, if third persons, who are not authorized, repair or change the device.

16.2. Service

We see SERVICE as a very important element in our business. That is why we are still available to you even after the guarantee period has expired.

An immediate repair will be carried out if you bring your meter to one of our approved service centers listed below.
You can obtain immediate help from our engineers by telephone.

16.3. Information on disposal

You may hand in any defective batteries taken out of the unit to our company as well as to recycling places of public disposal systems or to selling points of new batteries or storage batteries.

In the European Union, electronic equipment does not belong into domestic waste but – in accordance with Directive 2002/96/EC of the European Parliament and of the Council of 27 January 2003 on Waste Electrical and Electronic Equipment – must be disposed of in an expert manner. If you do no longer need this unit, please dispose of it in accordance with the applicable statutory provisions.

e-Mail: [email protected] www.woehler.de