HOOD

From Big Medical Encyclopedia

HOOD — the device for work with volatile substances, and also for their storage, attached to system of the exhaust ventilation for the purpose of prevention of intake of these substances in a workroom. To V. Highway carry also boxes for work with radioactive materials.

Fig. 1. The hood for hygienic and chemical laboratories.

In the figure 1 it is shown to V. Highway, to-ry it is used in hygienic, chemical and other laboratories. Speed of the movement of air in working apertures of B. highway shall be that more, than the volatility and toxicity of the emitted gases and vapors and than above their temperature are more. For low-toxic gases it makes 0,25 m/s, for more toxic — 1,5 m of sec. On a front wall of V. Highway there are lifting doors with latches for their installation at any height. Not glazed surface of V. Highway outside is painted by an oil paint or a varnish, inner surfaces are covered with an oil paint or ceramic tiles. In V. Highway the sink with water taps for a hot and cold water is mounted, the gas burner and heating devices are established. V. Highway shall have an eyeliner of compressed air. Air from V. Highway is removed on the special exhaust channel connected to an exhaust system of the building. In a back wall of V. Highway arrange exhaust openings: lower — for devolatilization at the time of their education, upper — for removal of lighter gases. In operating time under a door it is necessary to establish a crack in 50 — 100 mm since at densely closed doors air circulation is insufficient.

Boxes for work with radioactive materials

Fig. 2. Protective universal boxing of 2UKZ: at the left — glove, on the right — protective in which all operations are carried out by means of manipulators.

Tight boxes for work with a large amount of beta and gamma-active substances have more difficult design and management (see. Radiological laboratories, Radiological protective processing equipment). E.g., boxing protective universal 2UKZ (fig. 2), it is possible to carry out works with drugs of cobalt-60 as activity to 50 mkyura to Krom, consists of two sections connected by a reducing flange: left — glove boxing on one workplace 1 KA-NZH, right — protective boxing of KSh. All operations in boxing of KSh of 0,6 m 3 are carried out by means of manipulators. The boxing of KSh consists of two departments: the left department — reception, is intended for receiving and delivery of radioactive materials and their distribution on sections, and also for their temporary storage; the right department — working, is intended for work with radioactive materials. The case of boxing is made of stainless steel, revetted with protective pig-iron or steel plates and installed on a support from carbon steel. The boxing is equipped with the lamp of daylight, the ventilating device (stitched and exhaust the filters placed in the protection cover and an air duct), containers collections for liquid and solid waste, spring savories sprayers for deactivation of an inner surface of boxing. The working area of each filter makes 0,25 m 2 , normal depression in boxing — 20 mm w.g., frequency rate of air exchange up to 30 volumes an hour, the most admissible temperature in boxing 60 °. In a support communications for supply of reagents, cold and hot water, compressed air, household gas, power supply, the device for discharge of effluent (in the special sewerage or in a container for effluent), and also a container collection for solid radioactive waste are placed.

Fig. 3. The round box 9B-OS on two workplaces. Fig. 4. The ZSh-NZh hood on three workplaces.

The round box (fig. 3) 9B-OS on two workplaces is intended for works with the radioactive and chemically aggressive substances (except organic solvents) which are in various aggregate states. Work in boxing is carried out under depression, controlled by a tyagonaporomer.

In boxing of 0,15 m 3 it is possible to carry out works with cobalt-60 as activity to 0,1 mkyur. All operations with alpha and beta active agents are carried out in the rubber gloves fixed on holders of a wall of boxing. For performance of operations with gamma-active isotopes in addition use adaptation of distance steering. The case of boxing cylindrical, is installed on the metal support covered with chemically resistant enamel. The boxing has a removable spherical cover, edges is a glory-hole. I will eat windows (to dia. 20 cm) serves as the charging door. The boxing is equipped by one work, forkamery for receiving and delivery of objects, and the replaceable equipment. In a cylindrical wall of boxing the exhaust branch pipe and three cranes for input to the box of liquids and gases are located. At deactivation the hose for supply of reagents, and from the inside — a spring savory outside joins one of cranes. To a table-top of boxing the funnel for discharge of effluent and the collection for solid waste fastens. The boxing is equipped with stitched and exhaust filters of 0,1 m 2 everyone. Normal depression in boxing makes 20 mm w.g., frequency rate of air exchange up to 30 volumes an hour, the most admissible temperature no more than 50 °.

During the works with radioactive materials, with evaporation of solutions, using konts. acids, volatile or emaniruyushchy compounds use special V. Highway, e.g. ZSh-NZh on three jobs (fig. 4). In a case it is possible to carry out works with cobalt-60 as activity to 0,1 mkyur. The case of a case is made of stainless steel and installed on a support from carbon steel. An outer surface of the case, and at a support outside and inner surfaces are covered with chemically resistant enamel. On a front wall of a case three apertures of a rectangular shape closed by mobile blinds from organic glass are had. Each blind rises manually and is fixed by locks. The case is equipped with lamps of daylight, the ventilating device (two stitched and two exhaust filters of 9 sq.m everyone with air ducts), a spring savory sprayer for deactivation of an inner surface of a case. In a support communications for supply of reagents, a hot and cold water, compressed air, household gas, the electric power, the container KZhO-10 are placed. Management of electrical supply, waters, air is etc. carried out outside by manual cranes. It agrees the basic a dignity. settlement depression not less than 20 mm w.g. shall be provided to rules of work with radioactive materials and other sources of ionizing radiation (OSP-72) in tight cameras and boxes at the closed apertures. The camera and boxes shall be supplied with devices of control of depression. Air ducts of the exhaust ventilation and filters are calculated on a possibility of ensuring speed of the movement of air in periodically opened apertures of boxes and cameras, equal 1 m/s. At presentation of special production requirements and in the presence of warm, moisture allocations in boxes and cameras necessary air exchanges are defined by calculation. Temporary decrease in size of depression in cameras and boxes within production characteristic of filters is in use allowed, but it is not lower than 10 mm w.g., and also of the speed of air in the opened apertures of V. Highway, but it is not lower than 0,5 m/s on condition of preservation of purity of the air environment of workrooms within annual average admissible concentration. In the presence of more than three boxes total quantity of the deleted air is determined by number of the apertures which are at the same time opened in use by production schedules with degree of safety 1,5 and the accounting of possible thinnesses of all system. The fans servicing V. Highway, boxes and cameras it is necessary to have in special certain rooms. All fans shall have the light alarm system at actuators of engines.

See also Ventilation .


Bibliography: Voskresensky P. I. Technology of laboratory works, M., 1973; Ground health regulations of work with radioactive materials and other sources of ionizing radiation (OSP-72), M., 1972.

Yu. V. Novikov.

Яндекс.Метрика