Iran Occupational Health

Background and aims: The power plants, including important industry of the country in which a large number of noise sources which workers are exposed with harmful levels occupational noise. The aim of this study was designing enclosures to noise control in the feed water pumps in a power plant.

Methods: This cross-sectional study and their Interventional plants were done on the ground floor of the turbine unit of a thermal power plant on 2014. The feed water pumps in the preliminary stage of study, in the ground floor was determined the major noise sources. The Sound power level of the main sources were estimated according to the ISO 3746. To determine the distribution of the sound pressure level measuring and frequency analysis on the vertical axis for the study sources we used the SLM model TES 1358 and the measuring technique was small scale mesh networking and using the SURFER software for interpolation calculation and noise map drawing. Eventually, in order to control the noise we designed a multilayer enclosure for this pump and the effectiveness of this layer was estimated.

Results: The results of the noise analysis of this pumps showed that the dominant frequency of the noise were 2000 Hz. The results of the noise separation in the vertical axis of the sources confirms that the main pump and gearbox has the largest share in the noise distribution. The results also showed that the sound power level of the main pump is 107dB and of the gearbox is 108 dB. The design of the enclosure contains a primary layer made of steel and the inner layer made of rubber foam.In this design, including a percentage of noise leakage, the sound pressure level of the main parts of the pump will be reduced by 20 dB.

Conclusion: Enclosing technique can be reduced of noise levels for boiler feed water pumps. This result could protect the workers against harmful noise to the permissible limits.