ULTRASONIC LEAK DETECTION 2

Heat Exchangers, Boilers, Condensers

DESCRIPTION

Leak Detection of heat exchangers, boilers and condensers most often involves inspection of three generic areas: tubes, tube sheets and housings. The Ultraprobe can be used to detect leaks three ways: pressure leaks, vacuum leaks or by utilizing a unique UltratoneTM Ultrasonic Tone transmission method.

While it may be necessary to take a unit off-line to inspect for leaks, with ultrasound, it is often possible to perform an inspection while on-line or at partial load.

How Ultrasonic Leak Detection Works

During a leak, the fluid will flow from high pressure to low pressure producing a turbulent flow at the leak site. This turbulence has strong ultrasonic components which are sensed by the Ultraprobe and translated (via heterodyning) into the audible range where they are heard in headphones and seen as intensity increments on a meter.

Leak Detection Method

Most often leak detection is concerned with tube leaks. In heat exchangers and condensers, there are situation where the end plates (headers) are removed or water boxes are isolated while the unit is still on-line or at partial load. The tube sheet are scanned while listening for a distinct "hissing" or "rushing" sound of a leak. By adjusting the sensitivity of the instrument to help discriminate direction, move in the direction of the tube with the loudest sound.

Should the unit require off-line inspection, it is possible to use the Ultratoneô Ultrasonic Tone transmission method. Using ultrasonic transmitters such as UE Systems' patented Warble Tone Generators, the heat exchanger is flooded with intense ultrasonic sound waves on the shell side and the tube sheet is scanned for a distinct high pitched warbling sound coming from the leak. As above, adjust the sensitivity to discriminate direction and follow the sound to the loudest point which will be the leaking tube.

While under pressure or vacuum, fittings and casings may also be checked for leakage in a similar manner.

ULTRASONIC LEAK DETECTION

DESCRIPTION

Ultrasonic leak detection is extremely broad based. Sensing ultrasounds generated by a leak, the ULTRAPROBE can be used to locate leaks in pressurized systems regardless of the type of gas used. This is especially beneficial in areas where there is a saturation of gases or where a wide variety of gases, pressurized vessels and vacuum processes exist.

Time and convenience are also improved with ultrasonic detection since equipment may be tested while on-line.

How Ultrasonic Leak Detection Works

During a leak, a fluid (liquid or gas) moves from a high pressure to a low pressure. As it passes through the leak site, a turbulent flow is generated. This turbulence has strong ultrasonic components which are heard through headphones and seen as intensity increments on the meter. It can be generally noted that the larger the leak, the greater the ultrasound level.

Leak Detection Method

Ultrasound is a high frequency, short wave signal. The intensity of the ultrasound produced by a leak drops off rapidly as the sound moves away from its source. For this reason, the leak sound will be loudest at the leak site. Ultrasound is considered fairly "directional" and therefore, locating the source (i.e. the location) of the leak is quite simple.

For detection, scan the general area of a suspected leak and listen for a hissing sound (similar to the sound you hear when you fill a tire with air). Move in the direction of the loudest sound. If it is hard to determine the direction of the noise, reduce the sensitivity until direction can be established. Follow the sound and continue to reduce the sensitivity to determine the direction of the leak. In order to confirm the leak site, move the scanner back and forth over the suspect area. The sound level should increase as you pass over the leak. In some loud factory environments, frequency tuning may be required.