plasma LOW-TEMPERATURE, professional harm

From Big Medical Encyclopedia

Tekhnol, the processes based on the plasma-arc heating widely are used at plasma drawing coverings (metallization), cutting, welding, plasma machining of metals etc.

The major adverse factors at tekhnol, P.'s use N are an intensive high-frequency noise in a combination with ultrasound, the dust (aerosol) containing toxicants, gases, electromagnetic radiations of broad range, high concentration of aeroions. At the induction or arc category there is a danger of defeat by electric current. Feature noise (see) consists in a wide range of fluctuations (from 31 to 40 000 Hz) with placement of the main energy in the range of 2 — 20 kHz. Similar distribution of fluctuations is characteristic of work of plasmatrons of different function. The general noise level during the works manually makes more than 100 dB And. The formed aerosol represents complex parogazopylevy mixture which solid phase consists of compounds of metals (oxides, double oxides). The gas component is made ozone (see) and oxides nitrogen (see). Formation of an aerosol of high dispersion (generally particles up to 1 micron in size) with active sorption properties promotes deep penetration of such aerosol into respiratory tract and defines its all-toxic properties.

The range of electromagnetic oscillations of P. of N includes ultraviolet, infrared light radiation. Prevails ultraviolet radiation (see) which power depends on power characteristics of plasma and the processed materials. Influence of short-wave ultraviolet radiation is resulted by ionization of air with formation of ozone and nitric oxides at considerable distance from a source. In operating time of plasmatrons the maintenance of average and heavy ions in air increases up to considerable concentration. Intensity of infrared radiation (see) at metallization — 0,4 — 1 kal/cm 2 in a minute, during the cutting 1,5 — 2 kal/cm 2 in a minute, from heated metal during the cutting can reach 4 kal/cm 2 in a minute. Use as generators of plasma of high-frequency plasmatrons is followed by electromagnetic radiations of high-frequency range, to-rye are not indifferent for an organism (see. Electromagnetic field ).

Changes in the state of health of workers owing to the combined influence of all harmful production factors are shown by vegetovascular dysfunction which consequence arterial hypertension or hypotension (can be see. arterial hypertension , Hypotension arterial ), coronary heart disease (see). Workers with an experience have more than 5 years, especially during the work manually, can be observed the progressing decrease in auditory acuity up to development of cochlear neuritis (see. Relative deafness , Deafness ), atrophic changes of a mucous membrane of upper respiratory tracts.

Automation tekhnol, process — fundamentals of occupational health. At distance steering noise level in a workplace decreases by 10 — 15 dB, and concentration of harmful substances do not exceed maximum allowable concentration. Design effective local and all-exchange is important ventilation (see). Feature of the local exhaust ventilation in productions where P. is applied by N, is the suction of air from the lower zone with a speed in the working section of the shelter not less than 1,5 m/s, at other tekhnol, processes types of suctions are defined by options of the processed designs. At design of plasma sites it is necessary to provide such finishing materials which coefficient of a sound absorption is expected a high-frequency range of noise for rooms, cabins, cameras. Protection against electromagnetic radiations is provided with shielding of plasma in all cases of its use. Operators of plasma installations shall apply individual protection equipment from noise, UF-i light radiation. During the works manually, and also in the closed or half-closed spaces use of individual means of protection of a respiratory organs is obligatory. In a complex medical - a dignity. preventive actions the important place is taken preliminary, at revenues to work, and periodic medical examinations of workers (see. Medical examination , Professional selection ). Frequency and content of surveys, and also the list of contraindications to employment in contact with P. of N are regulated by the relevant orders M3 of the USSR.

Bibliography: Ilnitskaya A. V. Hygienic value of professional factors at plasma cutting, the Gigabyte. work and the prof. having got sick., No. 11, page 14, 1970; Ilnitskaya A. V. and d river. Hygienic assessment of new installations for plasma cutting, in the same place, No. 3, page 22, 1980; Levin A. I., etc. The state of health of operators of plasma installations, in book: Clinic and vopr, examinations of working capacity at zabol., caused by influence fizich. factors, page 136, M., 1972; H i with k i s h D. E. a. With h a 1 1 e n J. R. A preliminary study of some health hazards in the plasma jet process, Brit. J. industr. Med., v. 20, p. 95, 1963; M£lek B. Problematica ochrany zdravi pri praci s plazmovymi horaky, Zvaranie, sv. 19, s 56, 1970.

A. V. Ilnitskaya.