Tuesday, October 18, 2011

Death of Armed Police in Nepal due to Blast of Computer

CRT Monitor Health Hazard
i am quite socked seeing the news about the blasting of computer leading to death of police officer at Birgunj, Nepal. especially CRT (Cathode Ray Tube) monitor operates at high voltage and is the energy reservoir. CRT system retains the high voltage energy for a long period of time even if it is shutdown. May be the following literature helps find out the cause of computer blast in Birgunj.

CRT Monitor Health Hazard
Have you ever walked across a carpeted floor and gotten a shock when you touched a doorknob, table, counter, or even another person? that little shock you got was a result of static electricity. It was also many times what is needed to destroy some computer components.
You see, humans can't feel a static shock until it is several thousand volts strong, but it takes less than 30 volts to damage a sensitive computer component, such as a stick of RAM or a processor.
That's why computer technicians and home computer builders have to guard their computers against the deadly ravages of static electricity, as well as take steps to avoid injury to yourself. A shock that you can't even feel can seriously damage your homebuilt computer before you're even finished building it.
Electromagnetics: Some believe the electromagnetic fields emitted by CRT monitors constitute a health danger to the functioning of living cells. Exposure to these fields diminishes by the inverse square law which describes the propagation of all electromagnetic radiation: double the distance, quarter the power. Likewise, the EM energy is also less intense for the display's user than for a person located behind it because the deflection yoke is behind the display's screen and therefore closer to the rear. It is well-known that electromagnetic waves of sufficient intensity can harm human cells (see ionizing radiation) but it is not currently well-established that the weaker radiation commonly emitted by electronic devices such as a CRT has long-term health effects (see Electromagnetic radiation hazard and Bio-electromagnetics).

Ionizing Radiation: CRTs also emit very small amounts of X-rays as a result of the electron beam's bombardment of the shadow mask/aperture grille and phosphors. Almost all of this radiation is blocked by the thick leaded glass in the screen so the amount of radiation escaping the front of the monitor is mostly harmless. The Food and Drug Administration regulations in 21 CFR 1020 are used to strictly limit, for instance, television receivers to 0.5 milliroentgens per hour (mR/h) (0.13 ┬ÁC/(kg·h) (at a distance of 5 cm from any external surface and as mentioned above, most CRT emissions fall well below this limit. Early color television receivers (many of which are now highly collectable, see CT-100) were especially vulnerable due to primitive high voltage regulation systems. X-ray production is generally negligible in black-and-white sets (due to low acceleration voltage and beam current) and virtually every color display since the late 1960s when systems were added to shut down the horizontal deflection system (and therefore high voltage supply) should regulation of the acceleration voltage fail.