Gracey & Associates Hire

Bruel & Kjaer 2250

All 2250 meters come with the SLM module enabled, making the instrument fully capable of performing broadband measurements at the workplace and outdoors. It complies with the latest international standard [IEC 61672-1] as well as the previous international and national standards. All quantities are measured at the same time. For example, A and C frequency weighted levels are measured simultaneously, and at the same time F, S and I time weightings are applied in parallel. In addition, Peak levels are measured. Full statistics are also computed on-the-fly. Combine this with the dynamic range exceeding 120 dB and you will never miss a beat! You get all the parameters in one attempt, under-range is non-existent and you will have difficulties provoking an overload. The detailed list of available parameters can be found in the specifications section. You choose what you want on the display, but all other parameters can be inspected and reported, at any time. The standard package allows you to document your measurements with written notes and voice annotations. This is precision measurements made simple, which is further enhanced by the ability to save and recall setups, making it fast and easy to ensure that the right setup is used (frequency weightings, duration, and so on). Voice annotations are recorded using a separate commentary microphone when the commentary push button is pushed and held. Voice annotations and notes can be attached before, during and after the measurement. Spoken comments during the measurement should, of course, be made during a pause or with the microphone placed at a distance using an extension cable. These unique features allows you to document your measurement (where, when, how, etc.,) and always have this information attached to the measurement. Notes and voice annotations can be reviewed on the instrument itself or after the data has been transferred to a PC. If Sound Recording Option BZ 7226 is also enabled, you can record all or part of the measured signal. This recording is safely stored with the measurement. Thus it is easy to document that measured levels are indeed related to a particular noise source under investigation.

Type 2250's optional frequency analysis software allows real-time measurements in 1/1- and 1/3-octave bands, making it a simple matter to obtain spectra in order to, for example, select hearing protection, qualify heat and ventilation systems, and assess tonality. The following frequency ranges are available: 1/1-octave spectra (centre frequencies 8 Hz to 16 kHz) 1/3-octave spectra (centre frequencies 6.3 Hz to 20 kHz) In each band you have a full and unrivalled dynamic range from the noise floor in that particular band to 140 dB. That is a dynamic range generally in excess of 135 dB. Spectra can be A-, C- or Z-weighted. Five spectra and full spectral statistics are measured and stored and, in addition, seven different LN spectra and instantaneous values are available for display. Two spectra, for example, a minimum and maximum spectrum, can be superimposed on the display. As a matter of course, all the broadband quantities measured by Sound Level Meter Software BZ 7222 are computed in parallel with the frequency analysis. Spectral analyses can be documented using notes and voice annotations. If Sound Recording Option BZ 7226 is also enabled, you can record all or part of the investigated signal. This recording is safely stored with the measurement, allowing you to produce convincing documentation that the high levels in the 4 kHz band, are in fact related to a hiss from a particular piece of machinery.

With the optional Logging Software enabled, Type 2250 becomes a versatile instrument for obtaining time histories. The Logging Software allows you to select freely among the broadband parameters and log them at intervals from 1 s to 24 h. At the same time LAeq and/or LAF can be logged at 100ms intervals. If Frequency Analysis Software BZ 7223 is enabled, the Logging Software additionally lets you log spectra at the same 1 s to 24 h periods. Logging Software BZ 7224 incorporates a number of features designed to make difficult field work as manageable as possible. Among the most salient of these features are the following: Five user-definable markers can be set on-the-fly in the profile. Use these, for example, to clearly indicate specific noise sources Markers can be set directly on the profile display using the stylus and the touch screen. Simply 'tap and drag' on the part of the profile you want to mark and select a marker from the drop-down list Markers can even be set 'after the fact'. The display covers the latest 100 samples (that is, 100 s of profile when logging at 1 s intervals, otherwise more) meaning that in most cases you can wait for the event (or disturbance) to stop before placing your marker. Alternatively, scroll back in the profile and set your marker The profile display can be 'frozen' at any time (this happens automatically when you tap the screen), allowing you to work at ease Voice annotations, using the commentary microphone, are attached to the exact point on the profile where the annotation is made. With the microphone on an extension cable, comments can be associated with particular parts of the profile without interfering with the measurement

All markers and annotations are saved with the measurement, see Fig. 8 and Fig. 9. No further bookkeeping is required. When exporting data to, for example, 7820 Evaluator software for further analyses, markers, as well annotations, are directly accessible on the profile. Data are stored directly on SD or CF cards. BZ 7224 includes a suitable SD card. Data can be directly read from the SD card by the included PC software BZ 5503 (see page 11). This means that even large amounts of data can be quickly transferred to a PC. In order to give an indication of the amount of memory required, some examples have been listed in the following section. Values should be compared to the standard size of the SD cards used, which start at 128Mbyte. For convenience, values for 1 s logging periods during 24 h are given. Other values easily compute from these: Five broadband parameters, no statistics: 1Mbyte All broadband parameters, one 100ms parameter: 3Mbyte All broadband parameters, no statistics: 4Mbyte All broadband parameters, one 100ms parameter, all 1/3-octave spectra: 30Mbyte All broadband parameters with full statistics: 51Mbyte All broadband parameters, one 100ms parameter, all 1/3-octave spectra, full statistics: 80Mbyte Space needed for annotations and recordings must, of course be added to this. As a guideline, 10 s of voice annotation requires approx. 312 kB. If Sound Recording Option BZ 7226 (see following section) is also enabled, Logging Software BZ 7224 becomes even more versatile. In this case the actual signal can be recorded during, for example, a noise event. Recordings can be controlled manually, or automatically by a level trigger. BZ 7226 includes a pre-recording of sound (size of buffer dependent upon sample rate, see specifications), which means that sound recorded prior to the identification of an event is also included in the recording. The combination of recording the actual signal and making voice annotations on a separate channel provides exceptional documentation capabilities.