The problem of refinery noise has received increasing attention of late in three aspects; conservation of employee's hearing, speech interference and nuisance to neighbours. Air-borne sound is a variation in normal atmospheric pressure measured in "decibels" with reference to a sound pressure 0.0002 microbar. The other important sound variable is frequency. Tentative "Damage Risk Criteria" have been advanced, relating potential impairment of hearing to the intensity and frequency of sound to which the ear is continuously exposed. A large modern refinery will contain many sources of high intensity sounds which are potentially injurious. Personnel working in pumphouses or close to furnaces or turbo-blowers are particularly liable to hearing impairment owing to continuous exposure to sound pressure levels in excess of 100 db. Simple furnace burner muffling can give 10 db, that is threefold, sound pressure reduction without adversely affecting performance. Alternatively, as with pumphouses, operations ean be protected from noise by the construction df sound absorbing walls around control panel areas. As a last resort, operating crews can be provided with ear plugs whieh can give attenuations up to 30 db. Refinerim have been receiving increasing numbers of complaints from neighbours about noise nuisance. In general, the offending noise is from furnaces and stacks. The former can be muffled in the same way as for hearing conservation. Owing to the height from which it i3 radiated, the sound from the regenerator vent stacks of Cat. Crackers and Hydroformers can be a serious source of annoyance. Reductions of up to 30 db in sound level are being achieved by the installation of sound absorbing baffles in the stacks. Future work includes the establishment of hearing conservation programmes, involving periodic checks of hearing ability, for refinery personnel. This will enable the deterioration of hearing ability to be detected before it becomes serious and will give an indication of the effectiveness of sound reduction measures.
Le problème du bruit de raffinerie a récemment fait l'objet d'un redoublement d'attention portant sur trois points principaux: conservation de l'ouïe du personnel, entrave à la eonversation et atteinte aux droits des voisins. Le son porté par l'air consiste en une variation dans la pression atmosphérique normale mesurée en "décibels" par rapport à une pression sonore de 0.0002 microbar. L'autre variable sonore importante est la fréquence. A titre d'essai, on a stipulé des "critères de risques de dégâts" rapportant l'altération éventuelle de l'ouïe à l'intensité et à la fréquence sonore auxquelles l'oreille est continuellement exposée. Une grande raffinerie moderne comporte de nombreuses sources de sons à haute intensité éventuellement nocifs. Le personnel travaillant dans les
