Instructions There are 3 different practical in the environmental management file with all the readings taken during lab practical. (diagrams and fonts in red are the readings and calculations) Student has chosen practical 2 so you need to write a lab report on it. requirements of the lab report attached The required number of words for the report is 2000 words, +/- 10%/n MDIS Management Development Institute of Singapore Where lifelong learning begins LEEDS BECKETT UNIVERSITY Bachelor of Science (Honours) Safety, Health and Environmental Management Module: Environmental Management Name: Student ID: Batch: Page 1 of 2 Table of Contents • 1 Practical Investigations into Acoustics and Noise control ○ 1.1 A noise reducing enclosure 1.2 Workplace noise exposure assessment ○ 1.3 Predicting and controlling environmental noise 2 Practical investigations into air and water pollution .................... 4.1 Analysis of a detergent for phosphate and other constituents using visible spectroscopy 4.2 Introduction to gas measurement 4.3 Dust monitoring ○ ○ 4.4 Dispersion of air pollutants Page 2 of 2 LEEDS BECKETT UNIVERSITY BSc (Hons) Safety, Health and Environmental Management Environmental Management Laboratory Manual Practical Investigations into Acoustics and Noise Control Name: Student ID: Batch ID: Leeds Beckett University Practical 1; A noise reducing enclosure Introduction 11 The reduction of noise at source can involve a variety of different approaches, none of which on its own is capable of solving the problem. For example disposing of a noisy machine and replacing it with a quieter one may be the most effective way of reducing noise levels to an acceptable level, but even the quietest machine available may need further silencing. This practical looks at some of the considerations involved in enclosing a noisy machine. These can be summarised in three words; enclose, isolate and absorb. • The more complete the enclosure round a source, the more effective it will be. This can be checked by comparing levels from a complete enclosure with those found when it has a small hole. • When airborne sound has been reduced by ensuring a complete enclosure, the main contribution to sound emission will probably be energy transferred from the source to the enclosure itself, and to the surface it is mounted on and then radiated as sound. The effect of isolation can be tested by introducing a foam pad between the source and the enclosure. • Rather than increasing the mass of the enclosure materials, it may be more effective to line the enclosure with sound absorbing material. This does not impede the passage of sound energy to any appreciable extent, but it does tend to significantly reduce radiated sound energy by lowering sound levels inside the enclosure. One of the main problems to be overcome is that most machinery needs to be connected in some way to the outside world; materials must be fed in and finished work removed, power, ventilation and water supply may be needed, and access must be provided for maintenance. All these can reduce the effect of an enclosure by providing paths for structure-borne sound to escape. You are provided with a noise source, and with a simulated enclosure, which can be completed by a number of different panels. You are asked to investigate the effect of each possible configuration by measuring the noise reduction it provides. The effect of an enclosure varies with the frequency of the noise. The noise source used produces white noise, which contains all the audible frequencies. You will be measuring sound pressure levels using a frequency analyzer, which will give you a level for each octave band. Environmental Managements Acoustics Laboratory Manual MDIS-2024 Leeds Beckett University 12 Method The noise source can be powered by connecting an amplifier to the 4mm sockets on the outside of the enclosure. The front panels can be attached with butterfly nuts. The frequency analyzer provided is able to measure a complete noise spectrum, including the A and C weighted values, and print the results out in one go. The relevant controls are shown in the table below for the Norsonic 118 analysers. To start a measurement To finish a measurement To read out the results To start measurement a Press "start" Press "stop" Use and to move the cursor across the screen. The frequency band and sound pressure level are displayed for the current cursor position. The A and C weighted values are shown at the extreme right of the display new No need to reset; the instrument will over- write the previous measurement The microphone position should be recorded. Choose an (arbitrary) measuring position and measure the octave-band sound pressure levels under each of the conditions listed below. Measure under the following conditions; Enclosure front Enclosure lining etc # Noise 1 Off N/A None 2 On None None 3 On With hole None 4 On No hole None 5 On With hole 6 On No hole 7 On 8 On With hole No hole Stand the loudspeaker on a foam pad Stand the loudspeaker on a foam pad Line the enclosure with foam Line the enclosure with foam - Measurement 1 is there to establish the background noise in the room due to sources other than the one in the enclosure. So long as all your subsequent measurements are at least 10 dB above measurement 1, these other sources of noise have not influenced the result. If they are within 10 dB of measurement 1, then they would normally be regarded as unreliable. Check that all subsequent noise measurements with the noise source on (arrangements 2-8) are at least 10db higher at each octave band than the background measurement (measurement 1) at the corresponding octave band. Measurement 2 is the baseline measurement with no effective enclosure in place. By comparing your later measurements with this you will get an indication of how much difference each of the enclosures made. Environmental Managements Acoustics Laboratory Manual MDIS-2024/n

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