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Guidelines for the use of bactericidal lamps for disinfecting air and indoor surfaces
Guidelines prepared by a team of authors from a number of organizations: Institute of Preventive Toxicology and Disinfection (M.G. Shandala, Academician of RAMS - Head of Development, V.G. Yuzbashev, Candidate of Medical Sciences - Head of Medical Group), Institute of Zenit (A L. Wasserman, Candidate of Technical Sciences - head of the engineering group), Institute of Hygiene. F. Erisman (V.Vlodavets, doctor of medical sciences), Institute of Medical Instrument Engineering (V. Eliseev, engineer), Institute of Lighting Research (V.G. Ignatiev, candidate of technical sciences) , Research Institute of Building Physics (V.M. Karachev, Candidate of Technical Sciences), Research Institute of General and Communal Hygiene. ANSysina (Skobareva, Candidate of Medical Sciences), Information and Analytical Center of the State Committee for Sanitary and Epidemiological Surveillance of the Russian Federation (MK Nedogibchenko, San. Doctor, NE Strelyaev, epidemiologist).
INTRODUCTION
The fight against infectious diseases has always been considered an urgent task. One of the ways to successfully solve this problem is the widespread use of germicidal lamps. More than 40 years have passed since the first document on the use of germicidal lamps appeared in our country. Over the past period, the range of bactericidal lamps and irradiation devices has been significantly updated, numerous microbiological studies of the values of bactericidal exposures (doses) have been carried out to achieve the required level of bactericidal efficiency with various types of microorganisms when irradiated with radiation with a wavelength of 254 nm, and industrial designs of bactericidal irradiators have been developed.
When deciding on the release of a new version of the guidelines, the team of authors was guided by the goal of using the accumulated experience of using germicidal lamps and creating a document reflecting modern requirements and allowing them to significantly expand their use.
Of the numerous applications of bactericidal lamps, guidelines only cover the disinfection of air and indoor surfaces, as one of the most effective methods of controlling pathogens. It is important to note that the use of bactericidal lamps requires the strict implementation of safety measures that exclude the harmful effects on humans of ultraviolet radiation, ozone and mercury vapor.
Guidelines are designed for employees of medical institutions and sanitary-epidemiological surveillance bodies, as well as persons involved in the design and operation of irradiation facilities.
Guidelines are the basis for the development of job descriptions for the maintenance of germicidal installations by middle and junior medical and technical staff.
They are advisory in nature and will allow at a higher level to fulfill the requirements of existing regulatory documents governing the sanitary rules for the maintenance of various medical, children's, residential and industrial premises equipped with irradiating installations with bactericidal lamps.
Users of bactericidal irradiators should take into account that UV radiation cannot replace sanitary and anti-epidemic measures, but only supplement them as the final link in the treatment of the room.
1. BACTERICIDAL ACTION OF ULTRAVIOLET RADIATION
Ultraviolet radiation is known to have a wide range of effects on microorganisms, including bacteria, viruses, spores and fungi. However, due to the established practice, this phenomenon is called a bactericidal effect, associated with irreversible damage to the DNA of microorganisms and leading to the death of all types of microorganisms. The spectral composition of ultraviolet radiation, causing a bactericidal effect, lies in the wavelength range of 205-315 nm. Dependence of bactericidal efficacy in relative units Methodological guidelines on the use of bactericidal lamps for disinfecting air and surfaces in rooms on the wavelength of radiation
According to these data, the maximum bactericidal action occurs at a wavelength of 265 nm according to the latest publications (4, 5), and not 254 nm, as previously thought (15). In accordance with this, in the adopted system of effective units estimating the parameters of ultraviolet radiation, the radiation flux with a wavelength of 265 nm and a power of one watt, rather than a wavelength of 254 nm with a capacity of one bact. The transition coefficient between these systems of units for the maxima of the bactericidal action is equal to 0.86, i.e. 1 bact. = 0.86 Watt.
The bactericidal flux of the ultraviolet radiation source is estimated by the ratio:
Guidelines for the use of bactericidal lamps for disinfecting air and indoor surfaces, W,
where Methodical instructions on the use of bactericidal lamps for disinfecting air and indoor surfaces - spectral bactericidal efficiency in relative units;
Guidelines for the use of bactericidal lamps for disinfecting air and indoor surfaces - the spectral density of the radiation flux, W / nm;
Guidelines for the use of bactericidal lamps for disinfecting air and indoor surfaces - radiation wavelength, nm.
Then other quantities and units can be defined using the following expressions.
Bactericidal energy:
Guidelines for the use of germicidal lamps for disinfecting air and indoor surfaces, j,
where Methodical instructions on the use of bactericidal lamps for disinfecting air and indoor surfaces - the duration of radiation, p.
Bactericidal irradiance:
Guidelines for the use of bactericidal lamps for disinfecting air and surfaces in rooms, W / mMethodical instructions for using bactericidal lamps for disinfecting air and surfaces in rooms,
where Methodical instructions on the use of bactericidal lamps for disinfecting air and surfaces in rooms are the area of the irradiated surface, methodical instructions on the use of bactericidal lamps for disinfecting air and surfaces in rooms.
Bactericidal exposure (in photobiology is called the dose):
Guidelines for the use of bactericidal lamps for disinfecting air and surfaces in rooms, J / mMethodical instructions for the use of bactericidal lamps for disinfecting air and surfaces in rooms.
Bulk density of bactericidal energy:
Guidelines for the use of bactericidal lamps for disinfecting air and indoor surfaces, J / mMethodical instructions for using bactericidal lamps for disinfecting air and indoor surfaces,
where Methodical instructions on the use of bactericidal lamps for disinfecting air and surfaces in rooms are the volume of the irradiated air environment, mMethodical instructions on the use of bactericidal lamps for disinfecting air and surfaces in rooms.
Microorganisms are cumulative photobiological receivers, therefore bactericidal efficiency should be proportional to the product of irradiance by time, i.e. determined by the dose. However, the nonlinear characteristic of a photobiological receiver limits the possibility of a wide variation in the values of irradiance and time with the same bactericidal efficiency. Within the permissible error, you can change the ratio of irradiance and time in the range of 5-10-fold variations.
Quantitative assessment of bactericidal action Methodical instructions on the use of bactericidal lamps for disinfecting air and surfaces in rooms is characterized by the ratio of the number of dead microorganisms. Methodical instructions on the use of bactericidal lamps for disinfecting air and surfaces in rooms to their initial number. on the premises and estimated as a percentage.
Guidelines for the use of bactericidal lamps for disinfecting air and indoor surfaces.
Dependence of bactericidal efficacy Guidelines for the use of germicidal lamps for disinfecting air and indoor surfaces from a dose Methodical instructions for using bactericidal lamps for disinfecting air and indoor surfaces for microorganisms can be expressed using the equation
Guidelines for the use of bactericidal lamps for disinfecting air and indoor surfaces,%,
which reflects the well-known Weber-Fechner law, which establishes a link between the physical impact on a biological object and its response. This equation can be converted to
Guidelines for the use of bactericidal lamps for disinfecting air and surfaces in rooms, J / mMethodical instructions for the use of bactericidal lamps for disinfecting air and surfaces in rooms.
It allows you to determine the required dose value, if you specify the desired level of bacteri
It allows you to determine the required value of the dose, if you ask the desired level of bactericidal efficacy.
The following table 2 shows the experimental values of doses and bactericidal efficacy for some types of microorganisms when irradiated with radiation with a wavelength of 254 nm and the values of auxiliary coefficients "Guidelines for the use of germicidal lamps for disinfecting air and surfaces in rooms lamps for disinfecting air and indoor surfaces in the above equations.
2. BACTERICIDE LAMPS
Electrical sources of radiation, the spectrum of which contains the radiation of the wavelength range of 205-315 nm, intended for the purposes of disinfection, are called germicidal lamps. Due to the highly efficient conversion of electric energy, low-pressure discharge lamps have received the greatest distribution, in which during the electric discharge in the argonortuct gas-vapor mixture more than 60% is converted to the emission line 253.7 nm. High-pressure mercury lamps are not recommended for widespread use due to low efficiency, because their share of radiation in the specified range is not more than 10%, and the service life is about 10 times less than that of low-pressure mercury lamps.
Along with the line of 253.7 nm, which has a bactericidal effect, the emission spectrum of a low-pressure mercury discharge contains a line of 185 nm, which, as a result of interaction with oxygen molecules, forms ozone in air. In existing bactericidal lamps, the flask is made of UV glass, which reduces, but does not completely exclude, the output of the 185 nm line, which is accompanied by the formation of ozone. The presence of ozone in the air can lead, at high concentrations, to dangerous effects on human health or even fatal poisoning.
Recently developed the so-called bactericidal "bezosonny" lamp. For such lamps, due to the manufacture of a bulb made of a special material (quartz glass with a coating) or its design, the radiation output of the 185 nm line is excluded.
Structurally, bactericidal lamps are an extended cylindrical tube made of quartz or uviol glass. At both ends of the tube, the legs are soldered with electrodes mounted on them, which are pinned on both sides by two-pin bases.
Germicidal lamps are powered from a 220 V electrical network, with an alternating current frequency of 50 Hz. The inclusion of lamps in the network is made through a control gear (PRA), providing the necessary modes of ignition, ignition and normal operation of the lamp and suppressing high-frequency electromagnetic oscillations created by the lamp, which could have adverse effects on sensitive electronic devices.
The control gears are a separate unit mounted inside the illuminator.
The main technical and operational parameters of bactericidal lamps: spectral distribution of the radiation flux in the wavelength range of 205-315 nm; bactericidal flow Methodical instructions on the use of bactericidal lamps for disinfecting air and indoor surfaces, W; bactericidal recoil equal to the ratio of bactericidal flow to lamp power.
- lamp power Methodical instructions on the use of bactericidal lamps for disinfecting air and indoor surfaces, W;
- lamp current Methodical instructions on the use of bactericidal lamps for disinfecting air and indoor surfaces, A;
- voltage on the lamp Methodical instructions on the use of bactericidal lamps for disinfecting air and indoor surfaces, V;
- rated voltage of the network. Methodical instructions on the use of bactericidal lamps for disinfecting air and surfaces in rooms, V and frequency of alternating current. Methodical instructions on the use of bactericidal lamps for disinfecting air and surfaces in rooms, Hz;
- useful service life (total burning time in hours before the main parameters that determine the feasibility of using the lamp, go beyond the established limits, for example, the radiation flux drops to a level below the normalized value (indicated in the DUT).
A feature of germicidal lamps is the substantial dependence of their electrical and radiative parameters on the voltage fluctuations of the network. Figure 2 shows this dependence.
Fig.2. The dependence of lamp power P (l) and radiation flux Φ (l) on the mains voltage U (c)
Fig.2. Lamp power dependence Guidelines for using germicidal lamps for disinfecting air and indoor surfaces and radiation flux Guidelines for using bactericidal lamps for disinfecting air and indoor surfaces from mains voltage Guidelines for using bactericidal lamps for disinfecting air and indoor surfaces
With increasing voltage network, the service life of germicidal lamps decreases. So, with an increase in voltage of 20%, the service life is reduced to 50%. When the mains voltage drops by more than 20%, the lamps begin to burn unstably and may even go out.
In the process of lamp operation, the radiation flux decreases. A particularly rapid drop in the radiation flux is observed in the first tens of hours of combustion, which can reach 10%. With further combustion, the rate of decay of the radiation flux slows down. This process is illustrated by the graph in Fig.3. The lamp life is affected by the number of inclusions. Each switch reduces the overall lamp life by approximately 2 hours.
The temperature of the ambient air and its movement affect the value of the flux of the lamps. Such dependence is shown in Fig.4. It should be noted that "bezosonny" lamps are practically not sensitive to changes in ambient temperature. As the ambient temperature decreases, the ignition of the lamps becomes difficult, and the sputtering of the electrodes also increases, which leads to a shortened service life. At temperatures below 10 ° C, a significant number of lamps may not light up. This effect is enhanced at lower network voltage.
3 BACTERICIDE TREATMENTS
A bactericidal irradiator (BO) is a device containing a bactericidal lamp as a radiation source and intended to disinfect air or surfaces in a room.
BO consists of a body on which a bactericidal lamp, gear, reflector, fixtures and mounting devices are installed. The design of the BO must ensure compliance with the conditions of electrical, fire and mechanical safety, as well as other requirements that exclude harmful effects on the environment or humans. Under the terms of placement, bactericidal irradiators are divided into irradiators intended for use in stationary premises and installed on vehicles, for example, in ambulance cars. BO at the location are divided into ceiling, suspended, wall and mobile. By design, they can be open type, closed type and combined. Open type BOs are intended for the irradiation of air and surfaces in rooms with direct bactericidal flow in the absence of people by redistributing the lamp radiation inside large solid angles up to 4Methodical instructions on the use of bactericidal lamps for disinfecting air and surfaces in rooms. Closed-type bactericidal irradiators are intended for irradiating air and surfaces in rooms by direct and reflected bactericidal flow both in the absence and in the presence of people, the reflector of which must direct the bactericidal lamp flow into the upper hemisphere so that no rays either directly from the lamp or reflected from the parts of the irradiator, not directed at an angle of less than 5 ° upward from the horizontal plane passing through the lamp. Bactericidal irradiators of the combined type combine the functions of BO of the open and closed types. They have different separately switched-on lamps for direct and reflected radiation, or a movable reflector that allows the use of a bactericidal stream for direct (in the absence of people) or for reflected (in the presence of people) irradiation of a room.
One of the types of closed BO are recirculators designed to disinfect air by passing it through a closed chamber, the internal volume of which is irradiated by the radiation of germicidal lamps.
The speed of the air flow is provided either by natural convection, or by force using a fan.
Mobile BO, as a rule, are open-type irradiators.
Bactericidal irradiators have a number of parameters and characteristics that allow to evaluate their consumer properties and determine the most effective field of application. These include:
- type of feed, purpose and design;
- type of germicidal lamp and the number of lamps;
- network voltage Methodological guidelines on the use of bactericidal lamps for disinfecting air and surfaces in rooms (V) and frequency of alternating current Methodical instructions on the use of bactericidal lamps for disinfecting air and surfaces in rooms, (Hz);
- consumed volt-ampere power Methodical instructions on the use of bactericidal lamps for disinfecting air and surfaces in rooms (V · A), equal to the product of the network current Methodical instructions on the use of bactericidal lamps for disinfecting air and surfaces in rooms (A) on the network voltage Methodological guidelines for use bactericidal lamps for disinfecting air and indoor surfaces (B);
- consumed active power Methodical instructions on the use of bactericidal lamps for disinfecting air and indoor surfaces (W), equal to the total lamp power and losses in the control gear;
- bactericidal flux Methodical instructions on the use of bactericidal lamps for disinfecting air and indoor surfaces (W) emitted by an irradiator in space;
- coefficient of performance (EFFICIENCY) Methodical instructions on the use of bactericidal lamps for disinfecting air and surfaces in rooms, equal to the ratio of the bactericidal flow, irradiator to the total bactericidal flux of lamps.
Guidelines for the use of bactericidal lamps for disinfecting air and indoor surfaces
- bactericidal irradiation Methodical instructions on the use of bactericidal lamps for disinfecting air and surfaces in rooms (W / mMethodical instructions on the use of bactericidal lamps for disinfecting air and surfaces in rooms) at a distance of 1 m from the irradiator;
- productivity Methodical instructions on the use of bactericidal lamps for disinfecting air and surfaces in rooms (methodical instructions on the use of bactericidal lamps for disinfecting air and surfaces in rooms / h), equal to the ratio of the volume of air environment Guidelines for the use of bactericidal lamps for disinfecting air and surfaces premises (mMethodical instructions on the use of bactericidal lamps for disinfecting air and indoor surfaces) to the time of exposure etodicheskie instructions for use germicidal lamps for disinfecting air and surfaces in the area (h) required to achieve a given level of efficiency of bactericidal Guidelines for the use of germicidal lamps for disinfecting air and surfaces smokers (%) for a certain kind of microorganisms;
Guidelines for the use of bactericidal lamps for disinfecting air and indoor surfaces, mMethodical instructions for using bactericidal lamps for disinfecting air and indoor surfaces / hour.
Table 4 shows the main technical parameters and characteristics of industrial bactericidal irradiators, and table 5 shows the radiative and economic parameters.
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