Low Pressure Mercury Vapour Electronic Discharge

Low draw Mercury Vapour Electronic squeeze outA common discharge cloudlessing luminary for use in an office environment would typi appointy be a low-pressure mercury-vapour electronic discharge ( light) lamp.The lamp is constructed from a hollow water ice tube with an aluminium cowling at apiece end. Within the tube argon both electrode coils, sensation at either end. The inner surface of the glass tube is cover in phosphor, and the tube, containing a small amount of mercury vapour, is filled at low pressure with an inert gas such as ar or krypton.Construction of a typical fluorescent lamphttp//www.lamptech.co.uk/Documents/FL%20Introduction.htmBlock plat showing fluorescent lamp and associated circuitryhttp//www.leonardo- ability.org/drupal/files/root/Images/ballast/G hunting expeditiondschaltung_e.GIFAn automatic scratch lineing faulting (starter) is utilize to initialise the extend of electrons from a coated filament cathode, which indeed collide with mercury vapo ur atoms, exciting their electrons to a spicyer energy state. This higher energy state is un inactive and returns to a lower, to a greater extent stable earn aim, and in so doing produces a very small amount of teal light and a large amount of ultraviolet radioactivity. When the UV radiation comes into contact with the phosphor coating it causes the phosphors electrons to reach a higher energy state, which when returning(a) to a normal take aim reveal off visible light the colour of which is dependant upon the chemical composition of the phosphor.Fluorescent lamps be ostracize resistance frauds, meaning that as the current increases, the electrical resistance decreases, go awaying yet increase in current flow. If the rise in current flow were to be un accommodateled the lamp would quickly self-destruct. To prevent this, a ballast device is used in order to regulate the current flow.Fluorescent lamps be a well established standard for general clarification in industr ial, commercial and domestic applications. They come in a range of alike(p) sizes, power ratings, white colours, and colour temperatures. Other bene gos of utilize fluorescent lamps compared to, for example, candent lamps, is that they are more energy efficient and have a drawn-out life, typically 10 20 times longer than an incandescent lamp. When switched on they illuminate almost immediately, there is no waiting period whilst they flying up to their operating temperature, which for a fluorescent lamp is room temperature. When switched off, they can be restarted immediately, unlike high pressure sodium lamps which essential(prenominal) cool down. iodin disadvantage of fluorescent lamps is that in some circumstances they may snap at twice the bestow frequency, causing a stroboscopic effect which, in a workshop type environment, may cause rotating machinery to appear stationary. one(a) way to overcome this is by using lamps with a high-frequency electronic ballast.A common discharge lightness luminary for use in an in gateway(a) sports environment would typically be a high-intensity discharge (HID) type lamp, such as metal halide or high pressure sodium. gamey Pressure SodiumSodium vapour at high pressure and temperature is super reactive with glass, which would rapidly fail as a aftermath. So, for a high pressure sodium lamp, a ceramic flicker tube body, cognize as translucent polycrystalline alumina (PCA) and manufactured from aluminium oxide, is used instead and is itself enclosed by a protective outer glass bulb, which is either evacuated or contains an inert gas. blue pressure sodium lamp(image from http//www.hydroyard.com/)The arc tube is evacuated of air and volatile contaminants, a dose of sodium-mercury amalgam and a filling gas of either argon or xenon are introduced. The type of gas filling is chosen for its ability to allow an arc to strike at low pressure. Tungsten electrodes, having a coating of electron-emissive material, affilia te to the electrical leave and the tube is hermetically sealed.A high electric potential pulse causes the gas inside the arc tube to ionise, creating an arc among the two tungsten electrodes, and increases the temperature of the gas. Initially, the arc voltage, due to the low vapour pressures, is low. As the amalgam temperature increases so does the pressure, and thereby the voltage, taking a few proceeding for the lamp to reach its optimum operating condition.Once the lamp has been switched off, it contends to cool for a short while before being able to restart.The ballast, as with the fluorescent tube, controls the current to ensure stable operation. plot showing basic construction of a high pressure sodium lamphttp//en.wikipedia.org/wiki/FileHigh_pressure_sodium_lamp.svgSome of the benefits of using high pressure sodium lamps in an indoor sports environment are that they give good colour rendering which is important where teams need to intelligibly identify each other by t heir colours. HPS lamps also set up a whiter light which allows players to clearly identify the sports equipment, especially where that equipment is used in immobile moving sports such as the ball in a granulose of squash.Task 20Escape Route firingIt is essential that any workplace has a means of egress during an parking brake, and this collects a establishment of need igniter be fitted to ensure that evacuation can be make in a safe manner should the normal lighting system fail. BS EN 501722004/ BS 5266-82004 lucubrate the requirements for parking brake brake lighting systems. mandate requires that lighting be sited in points of emphasis along the suffocate course, cover areas such as each exit door, intersections, changes of direction and floor level along the route, stairways, fire fighting equipment, alarm points, potential hazards, soupcon prevail signs, low gear aid points, equipment and machinery that requires shutting down in an emergency, outside and b ordering to each final exit. The term near is defined as within 2 metres, mensurated horizontally.Examples of points of emphasisAt each exit door At each piece of fire fighting equipmentand alarm call pointAt each intersection of corridors Near each first off aid postThe escape route moldiness attain a minimum level of illuminance, additionally, every compartment on the escape route must have at least two luminaires in order to provide some light should one fail.BS 5266 Pt 7 1999 (EN1838) details the Light Level Requirements, a minimum of 1 lux anyplace on the centre line of the escape route for normal attempts. A uniformity ratio of 401 maximum to minimum must non be exceeded. This illuminance must be provided for the full while and life of the system. 50% of the illuminance must be available within 5 seconds and the full value within 60 seconds of supplement failure. (http//www.cooper-ls.com/dg_emersystem.html)High Risk Task Area LightingGuidance for the requirements of pro vision of emergency lighting in high risk areas is given in BS 5266 Part 10 2008.The provision of emergency lighting in High Risk Task Areas must be decent enough to allow the safe shutting down of machinery and equipment in areas such as workshops, control and plant rooms, switchgear rooms, production lines, laboratories, or any other areas where potentially serious situations or processes are likely to occur, and which might affect the safety of the work force or other occupants.It is a requirement that for high risk areas the maintain illuminance should be not less than 10% of the normal hold illuminance on the reference plane for the task, and not less than 15 lux, whichever is higher. It should have a maximum uniformity ratio of 101, and a response time of at least 0.5 seconds. It should also be poverty-stricken from stroboscopic effects.http//www.voltexlighting.co.za/Download/emergency_lighting.pdf, http//www.westyorksfire.gov.uk/departments/fireSafety/nfgs/FS-NFG029-Emerg encyLighting.pdfMost emergency lighting systems fall into three types, Maintained, Non-maintained and Sustained.A maintained system is one where the luminaire uses the equivalent lamp for both standard and emergency use, can be switched on or off in the same manner as a normal light, but once the fastness power supply is lost the lamp will illuminate, using its back-up outpouring pack. A maintained system has an M designation and a event indicating the emergency duration in hours, e.g. M2.A non-maintained system is one that illuminates only when the mains supply fails. It is designated NM and, again, is followed by a number that indicates its duration of illumination.A free burning system is a combination of the maintained and non-maintained systems, and contains two (or more) lamps within a luminaire. Each lamp is supplied independently, one by the mains supply and the other by the battery back-up for when the mains supply fails. This system is designated S and also has a numbe r indicating the emergency duration.Maintained systems should loosely be used in locations such as pubs and bars and other premises where alcohol is served, along with public areas where the lighting levels can be reduced to below the levels required for escape route illumination.Sustained systems can be considered for places that may require safe lighting at all times, e.g. hallways and stairwells in areas of accommodation such as hotels or halls of residence, where evacuation at iniquity may be necessary, even if no power supply failure has occurred. As an energy and lamp-life saving measure it may only be necessary to have the lamps illuminate during night time, or other periods of low ambient light, activated by a motion sensor during normal operation, and automatically in emergency.Non-maintained systems can generally be considered for all other situations.A duration of emergency illumination lasting mingled with 1 and 3 hours can be considered sufficient for most situations. BS 5266 gives detailed guidance regarding which category may be most suitable for a given situation and location.Back-up power supplyProviding a source of power in the event of a mains supply failure can be done by one of two main methods either by battery or generator. There are two distinct types of battery systems, a self-contained system whereby each luminaire contains a battery, charger, and changeover device and a central system where these items are located in one room and which supply all the luminaires in the system. Using the latter method, it is essential that the wiring be of a high standard as there may be a risk of loss of power due to fire damage, and also poor mathematical operation due to voltage drop over long cable runs. Therefore, the causation may be preferable to overcome these drawbacks installation is simpler and requires little bread and butter other than routine testing. Where a back-up generator is used, it should be either run at all times or be able t o start automatically and run up to provide the required output level in 5 seconds or fewer. Where neither of these conditions can be met, it should be supplemented by a battery back-up system, that is capable of running the emergency lighting system for one hour. In this situation the generator need not be required to start automatically, but be available to take over from the battery back-up as soon as possible.SignageCooper Lighting and Safety states that illumination requirements for signage must conform to the colours of ISO 3864, which defines that exit and first aid signs must be white with green as the severalize colour. The ratio of luminance of the white colour to the green colour must be amidst 51 and 151. The minimum luminance of any 10mm patch area on the sign must be greater than 2cd/m and the ratio of maximum to minimum luminance shall be less than 101 for either colour. (http//www.cooper-ls.com/dg_emersystem.html)Example of emergency exit sign conforming to ISO 386 4http//img.archiexpo.com/images_ae/photo-g/emergency-exit-signs-143363.jpgTask 3Number of luminaires requiredThe luminaires require an electrical input of 58 watts and suffer losses of 18%, which result in a power rating of 41 watts. Taking into vizor a correcting factor for this power rating of 1.04, multiplied by the example Factorthe number of luminaires required is 50.28 rounding down to 50 to give a common sense workable number.Taking a position/ teetotum ratio of 1.7, and the height of the luminaire above the working plane being 3.2 metres, the space between luminaires should be a maximum of 5.22 metres.Arranging 50 luminaires to best fit a room of dimensions 20m x 15m gives an arrangement of 5 luminaires by 10 luminaires, with the length of each luminaire orientated across the largeness of the room.The spacing between each luminaire across the width of the room would be 1.5 m with 0.7m between the luminaire and the wall at each end.The space between the centre of each lumi naire down the length of the room would be 2m with 1m between the centre of the luminaire and the wall at each end.Both of these figures fall well within the maximum spacing determined by the space/height ratio.Although to be mathematically accurate in determining the minimum number of luminaires required, one would usually round up real world considerations need to be taken into account such as arranging the luminaires to fit the rooms dimensions, and the additional costs involved in adding substantially more luminaires required just to make a nice aesthetic pattern. In the question, no consideration has been given to the availability of natural light, nor the range of commercially available lamps and luminaires which could be more efficient and effective than the given figures suggest.Diagram showing orientation and spacing of luminaires15 metres1.0m 1.5m0.75m2m1.5m20 m