Merits and demerits of the fluorescent lamp
The fluorescent lamp (the mercury lamp of low pressure, further in the text – LL) is the gas-discharge light source. Structurally it represents the glass tube with the phosphor layer applied on the internal surface. In end faces of the tube spiral electrodes are established. In the lamp there are rarefied vapors of mercury and inert gas. Under the influence of the voltage (field) attached to electrodes in the lamp there is the discharge through gases. At the same time the current passing through mercury vapors causes ultra-violet radiation.
Ultra-violet radiation, influencing the phosphor, forces it to shine, i.e. the phosphor will transform the ultra-violet radiation of the discharge through gases to visible light. Glass of which LL is executed interferes with the ultrafioletovogoizlucheniye exit from the lamp, that protecting our eyes from the radiation, harmful to them.
Exception are bactericidal lamps, at their production the uviol or quartz glass which is passing ultraviolet is applied. For today LL with In amalgams are widely adopted. Cd and other elements. More low pressure of vapors of mercury over amalgam gives the chance to expand the temperature range of optimum light returns to 600C instead of 18-250C for pure mercury.
At temperature increase of the environment over admissible norm (25oc for pure mercury and 60oc for amalgams) temperature of walls and the vapor pressure of mercury increases, and the luminous flux decreases.
Even more noticeable reduction of the luminous flux is observed at fall of temperature, so, and the mercury vapor pressure. At the same time also ignition of lamps sharply worsens that does complicated their use at temperatures lower - 10oc, without the warming devices. In this regard bezrtutny LL, with discharge of low pressure in inert gases are of interest.
In this case the phosphor is excited by radiation with the wavelength from 58.4 to 147 nanometers. As gas pressure in bezrtutny LL practically does not depend on surrounding temperature, invariable are also their light characteristics. Today the problem of work of LL at low temperatures is solved by use of LL of new generation, so-called lamps of T5 (with diameter of tube of 16 mm), compact fluorescent lamps and application for the power supply of LL of high-frequency electronic puskoreguliruyushchy devices (PRA).
Light return of LL increases at increase in the sizes (length) due to decrease in the share of the anode and cathode losses in the general luminous flux. Therefore it is more rational to use one lamp on 36 W, than two po18 W. Service life of LL is limited to deactivation and spraying (exhaustion) of cathodes. Also fluctuations of tension of the power line and frequent inclusions and switching off of lamps have an adverse effect for service life. When using EPRA these factors are minimized. Wide use of LL is connected with the fact that they have the number of considerable advantages in front of classical glow lamps:
- High performance: Efficiency - 20-25% (at glow lamps about 7%) and luminous efficiency in 10 times more.
- Long service life – 15000-20000 h (at glow lamps - 1000 h, strongly depend on tension) the power supply.
Have LL and some shortcomings:
- As a rule, all discharge lamps for normal work demand inclusion in network together with ballast. Ballast, it is the puskoreguliruyushchy device (PRA), - the electrotechnical device providing the modes of ignition and normal work of LL.
- Dependence of steady work and ignition of the lamp on ambient temperature (admissible range 55oc, optimum is considered 20oc). Though this range constantly extends with the advent of lamps of new generation and use of electronic ballasts (EPRA).
Let's dwell upon LL merits and demerits. It is known that optical radiation (ultra-violet, visible, infrared) renders on the person (its endocrine, vegetative, nervous systems and all organism in general) considerable physiological and psychological influence, generally salutary.
Daylight - the most useful. It influences many vital processes, the metabolism in the organism, physical development and health. But vigorous activity of the person continues and when the sun disappears for the horizons. The daylight is succeeded by artificial lighting. For many years for artificial lighting of housing only glow lamps – the warm light source which range differs from day in dominance of yellow and red radiation and total absence of ultraviolet were used (and are used).
Besides, glow lamps as it was already mentioned, are inefficient, koeffitsit them useful effect - 6-8%, and service life is very small – no more than 1000 h. The high technological level of lighting with these lamps is impossible.
That is why quite natural was the emergence of LL – the digit light source having 5-10 times big light return than the glow lamp, and at 8-15 times bigger service life. Having overcome different technical difficulties, scientists and engineers created special LL for housing – the compact, almost completely copying usual appearances and the sizes of glow lamps and combining at the same time its advantages (the comfortable color rendition, simplicity of service) with profitability of standard LL.
Owing to the physical features LL have one more very important advantage in front of glow lamps: the opportunity to create light of different spectral distribution – warm, natural, white, day that can significantly enrich the color palette of the house situation. Not accidentally there are special recommendations about the choice like LL (chromaticity of light) for different scopes. Availability of controlled ultraviolet in special lighting and irradiating LL allows to solve the prevention problem of "light starvation" for the city dwellers spending up to 80% of time in the enclosed space.
So, the lamps released by BIOLUX, range OSRAM LL of radiation of which it is approximate to solar and saturated with strictly dosed near ultraviolet, are successfully used at the same time both for lighting, and for radiation of inhabited, administration, school premises, especially at insufficiency of natural light.
Also special agar CLEO (PHILIPS) LL intended for acceptance of "solar" bathtubs in the room and for other cosmetic purposes are issued. When using these lamps it is necessary to remember that for safety it is necessary to observe instructions of the manufacturer of the irradiating equipment strictly. And now we will stop on shortcomings of luminescent lighting as which many rank its notorious "harm for health".
The discharge through gases nature such is that as it was already told above, any LL have the small share of near ultraviolet in the range. It is known that at overdose even of natural sunlight there can be unpleasant phenomena, in the particular excess ultra-violet radiation can lead to skin diseases, injury of eyes. However, having compared impact on the person during life of natural solar and artificial luminescent emission, the assumption of harm of radiation of LL becomes clear, how unreasonable.
It was proved that work within the year (240 working days) at artificial lighting of LL of cold this world with very high level of illumination of 1000 lx (it by 5 times exceeds optimum level of illumination in housing) corresponds to stay in the open air to Davos (Switzerland) within 12 days on 1 hour a day (at noon). It is necessary to notice that real conditions in premises happen in tens of times more sparing, than in the given example.
Therefore, it is not necessary to speak about harm of normal luminescent lighting. The physicians, hygienists and lighting technicians who took part in the unrolled scientific discussion held in Munich on the subject "Influence of Illumination of LL on Health of the Person" came to similar conclusions. All participants of the discussion were unanimous: adherence of rules of the competent device of lighting which include restriction of the straight line and the reflected brightness, restriction of the pulsation of the luminous flux, ensuring favorable distribution of brightness and the correct svetoperedacha completely will eliminate the existing complaints to luminescent lighting.
In the stated above list the important place is taken by the question of restriction of the pulsation of the luminous flux. The matter is that the traditional linear tubular LL connected to network by means of the electromagnetic puskoreguliruyushchy device (most often applied in lamps), create light non-constant in time, and "micropulsing", t.е. with the alternating-current frequency of 50 Hz which is available in network the pulsation of the luminous flux of the lamp occurs 100 times a second.
And though this frequency is higher critical for the eye and, therefore, the flashing brightness of the lit objects is not caught by the eye, the lighting pulsation at long influence can negatively influence the person, causing increased fatigue, decrease in working capacity, especially when performing hard visual works: reading, work at the computer, needlework, etc.
That is why the lamps which appeared for a long time with electromagnetic low-frequency PRA are recommended to be used in so-called "non-working" zones (utility rooms, povala, garages, etc.). In lamps with electronic high-frequency PRA the specified feature of work of LL is completely eliminated, but even such lamps with linear LL are rather bulky and are not always convenient for local (worker) lighting. Therefore chandeliers, wall, floor, table lamps it is reasonable to use the compact fluorescent lamps mentioned above to traditional lighting of housing.
And, at last, the last small note connected with operation of lamps with LL. For its work the mercury drop – 30-40 mg, and compact 2-3 mg is entered into the lamp If it frightens you, remember that the thermometer which is available in each family contains 2 g of this liquid metal. Certainly, if the lamp breaks, it is necessary to arrive the same as we arrive when we break the thermometer, – to carefully collect and remove mercury. LL in housing is not only more economic, than the glow lamp, the light source.
Competent illumination of LL has the set of advantages before traditional: profitability, abundance and beauty of light, uniformity of distribution of the luminous flux, especially in cases of highlighting of extended objects linear lamps, the smaller brightness of lamps smaller heat production is also considerable.
Today the most qualitative products and the wide range at our market are presented by world lighting brands:
- German firm OSRAM.
- The Dutch PHILIPS and some other which offer the broadest choice of high-quality LL for every taste and color.