Acoustical equipment

Echo sounding is carried out with acoustic equipment normally mounted underneath a ship. The two kinds of systems widely used in bathymetrical measurements are ... 

The stack manu cturing cost includes fibrication and design by an acoustic equipment manufacturer. 

The application of Acoustic Emission Examination (AE) during the inspection of pressure equipments, P Tscheliesnig - presented at the 3. Hungarian Conference on Safety Budapest, 1997... 

Tile new Pressure Equipment Directive (P.E.D.) established by the European Commission recognize acoustic emission as a complementary method which can be used to monitored pneumatic test when hydraulic test could not be perform. 

At present time is the acoustic emission laboratory of the Institute of Design already equipped with modem analysers processing 4 and 16 AE sensors (each enables to sense up to 256 levels). All analysers have at disposal powerful computing technique and corresponding software. 

As any conventional probe, acoustic beam pattern of ultrasound array probes can be characterized either in water tank with reflector tip, hydrophone receiver, or using steel blocks with side-drilled holes or spherical holes, etc. Nevertheless, in case of longitudinal waves probes, we prefer acoustic beam evaluation in water tank because of the great versatility of equipment. Also, the use of an hydrophone receiver, when it is possible, yields a great sensitivity and a large signal to noise ratio. 

The acoustical device component is placed in water and is configured like a conventional impulse echo equipment. The ultrasound wave passed the delay path and enters the specimen container through a very thin plastic window. The backside of the container is a steel plate and will also be used as a reference reflector to measure pn. 

It should be specially pointed out, that modem equipment for remote acoustics sounding gives the possibility to solve the most part of issues related to the water basin and river bottoms monitoring. 

The Institute has many-year experience of investigations and developments in the field of NDT. These are, mainly, developments which allowed creation of a series of eddy current flaw detectors for various applications. The Institute has traditionally studied the physico-mechanical properties of materials, their stressed-strained state, fracture mechanics and developed on this basis the procedures and instruments which measure the properties and predict the behaviour of materials. Quite important are also developments of technologies and equipment for control of thickness and adhesion of thin protective coatings on various bases, corrosion control of underground pipelines by indirect method, acoustic emission control of hydrogen and corrosion cracking in structural materials, etc. 

This aspect is not included here, but is related to optical flow diagnostics. It is based again on the principle of the optical Doppler effect. Multifunctional equipment is available for noncontact measurements of flow-induced vibration on surfaces of structural elements, for acoustic measurements, and for calibration of accelerometers and vibration transducers. 

As the measuring distance for such equipment can be up to about. 50 m, this technique is advantageous in cases when conventional acoustic or vibro-meter devices are difficult or even impossible to use, such as high-frequency vibration measurements on the walls of high-level air ducts. 

This requirement hides an important provision. It not only applies to inspection, measuring, and test equipment but to the measurements that are performed with that equipment. Anywhere you intend performing product verification or monitoring processes you need to ensure that the environmental conditions are suitable. By environmental conditions is meant the temperature, pressure, humidity, vibration, lighting, cleanliness, dust, acoustic noise, etc. of the area in which such measurements are carried out. To avoid having to specify the conditions each time, you need to establish the ambient conditions and write this into your procedures. If anything other than ambient conditions prevail, you may need to assess whether the measuring devices will perform adequately in these conditions. If you need to discriminate between types of equipment, the ones most suitable should be specified in the verification procedures. 

The ultrasonic cleaning bath is the most common source of ultrasound in the laboratory and was the equipment used in most of our investigations. The acoustic intensity is far less than the immersion horn but the low price, less than 200 for a 4" x 9 bath that holds flasks up to 1 liter in size, compared to nearly 2000 for a modest horn setup probably accounts for the difference in popularity. 

Moderate (attenuation and limitation of effects) Use vacuum to reduce boiling point Reduce process temperatures and pressures Refrigerate storage vessels Dissolve hazardous material in safe solvent Operate at conditions where reactor runaway is not possible Place control rooms away from operations Separate pump rooms from other rooms Acoustically insulate noisy lines and equipment Barricade control rooms and tanks... 

Turbines and gas compressors are normally provided as a complete assembly in an acoustical enclosure. Because the equipment is enclosed and handles gas supplies, it is a prime candidate for the possibility of a gas explosion and fire. 

The reaction is performed in the bath itself and is therefore subjected to direct sonication. The acoustic field is more regular throughout the reacting system as a single flat emitting face is used. The vessel itself is enclosed and can be equipped with the... 

Acoustic chemometrics has its greatest benefits in cases where haditional sensors and measurement techniques, such as flow, temperature and pressure transmitters cannot be used. In many processes it is preferable to use noninvasive sensors because invasive sensors may cause disturbances, for example fouling and clogging inside the process equipment such as pipelines, reactors cyclones, etc. In this chapter we concentrate mainly on new industrial applications for acoustic chemomehics, and only discuss the necessary elements of the more technical aspects of the enabling technology below - details can be found in the extensive background literature [3-5],... 

The acoustic sensor used for capturing process vibrations is often a standard accelerometer, covering a frequency range 0-50 kHz - or a so-called acoustic emission sensor (AE) often covering higher frequencies from 50 kHz up to several MHz. The 4396 and ATEX 5874 accelerometers from Briiel Kjaer are shown in Figure 9.2. The 4396 accelerometer is a standard accelerometer for industrial use and the ATEX 5874 is a certified accelerometer for use where explosion proof equipment is needed (EX certified). 

---