Sound level measurement data

When the unit was initially plaeed in serviee, sound level measurement data were eolleeted. Within 3 ft of the expander ease, sound levels were measured at 92-99 dBA. At the property line 25 ft away from the ease, the levels were 68-85 dBA. At the time of installation, there were no stmetures near enough to the faeility to be impaeted by any noise. However, as the surrounding area eontinues to develop, it may be neeessary to install sound attenuation equipment. 

Table 5.8 shows a summary of the results of the sound of explosions measured at the mock storage shed. Data is shown at the impulse level, and data from the fast level is usually 3.5-5.5dB lower than the impulse level data. Impulse levels were used for the dB values. The frequencies used for a linear response were l-90Hz for the special linear characteristic and 10-20Hz for the special flat characteristic. In many cases the explosive sound was measured over 100Hz to include the main components. One must pay close attention to methodology when comparing and analyzing measured values of sounds. 

Noise emissions are becoming increasingly important. With some refineries located near populated areas, it is important to keep noise to a minimum. Burner testing is usually conducted on a single burner and noise emissions are usually measured at a distance of approximately three feet from the burner air inlet. Data collected during the test includes an overall A-weighted sound pressure level and the sound level at each octave... 

The duration of the measurements, the microphones to be used, the type of data recorded, and the type of spectrum analyzers are among the numerous measurement conditions that can be varied before and after taking the smmd measurements. An example of the sound pressure record from two microphones at different locations, for a typical flare test, is shown in Figure 28.15. The spike at 0 seconds and again at about 10 seconds are from a safety horn alerting everyone in the area of an impending flare test. In this particular example, there was a rapid rise in the sound level at the start of the test followed by a steady decline as the fuel flow rate was reduced as dictated by the given test plan. 

The other type of survey has the purpose of finding out if conditions could create excessive exposures. In this kind of survey, measurements taken at various locations help determine noise sources or potential noise exposures at locations where people may be. During a survey, a user takes readings with a sound level meter in a grid pattern or at specific worker locations. The survey data then help with decisions on reducing noise exposures. 

Sound volume is a subjective perception which has no relationship to the actual noise intensity levels. Reference data between subjectively perceived sound volume and measured sound-level difference are as follows 1-2 dB difference is not yet registered, 8-10 dB difference in level is perceived as a doubling or halving of the sound volume. The acoustical environment perceived by man as agreeable is a sound level, devoid of any information, of from 15 to 20 dB (A). Lesser sound levels as well as essentially higher ones are perceived as a form of molestation. Any sound perceived by man as a subjective molestation or disturbance is called noise. 

The new OHD/Cirrus Research Optimus RTA Sound Level Meter measures all data in one measurement this includes the entire 120dB dynamic range. Just press three buttons, and you re done. Voice tag allows you to audibly notate the measurement, which means no need for keeping track of a log sheet. Tbe Optimus is small, lightweight and incredibly easy to use. Occupational Health Dynamics, www.ohdusacom/products/ sound level meters/optimus.php. Cnvfe 307... 

Sound level meters measure noise only at a given point at the time of observation. If the noise being measured is constant in both space and time, meters will give an accurate representation of the situation. However, if the sound level changes with time and location (for instance, as an operator moves around), it will be necessary to record either the sound level manually using short time intervals (5 to 10 s) or the noise data for later analysis of the time history of the noise. The second approach is preferable when a worker s noise exposure is related to duty cycles or product flow. In this case, extrapolations can be made on the basis of total day production to determine the noise exposure of an employee over a full day. 

Figures 11.11 and 11.12 present Uft-off characteristics of a hydrogen diffusion flame. The diagram in Fig. 11.11 was plotted using data from [23]. It is seen that liftoff occurs at a flow rate exceeding 600 m/s. The flame lift-off height grows linearly with increasing flow rate and can exceed the sound speed. Close results have been obtained in [30-32]. To evaluate the data discrepancy level, the line approximating the measured data from [23] is plotted with the experimental points obtained in [30-32].

A laboratory QA/QC program is an essential part of a sound management system. It should be used to prevent, detect, and correct problems in the measurement process and/or demonstrate attainment of statistical control through QC samples. The objective of QA/QC programs is to control analytical measurement errors at levels acceptable to the data user and to assure that the analytical results have a high probability of acceptable quality. 

Certain additional measurements are clearly needed in the Sound. An array of current meters and water level recorders should be operated on a cross section so that the lateral variation of the power flux can be reliably determined. Longer data runs for h and v are needed to adequately define the mean tidal dissipation. Simultaneous measurements of sediment resuspension and transport and of the tidal dissipation could be used to test the hypothesized interrelation between these quantities. 

Sound power level calculated from measured noise data, plotted versus heat release rate for different types of industrial flares... 

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