Where might eletrostatic charge be a hazard?

Answer 1

[Electrostatics generated by what is called triboelectric effect, occur all the time around us every day. We just don't notice most of the time. Anyone taking a piece of pastic wrap off a roll is generating static electic charges; that individual is actually separating charges to create voltage. In that case, the voltages are small, but in other cases, the voltages can become significant - and dangerous in the exteme!] The discharge of electrostatic buildup can be a major problem around volatile chemicals such as gasoline or other fuels. The spark created by the equalization of charge can ignite them. Worse, if vapors are present in a sufficient concentration, the combustion will be so rapid that there will actually be an explosion! Even dense dust clouds can combust when exposed to electrostatic discharge, as any workers around grain elevators are constantly trained to be aware of. One example involves fueling cars at a gas station in winter. Passengers who leave the vehicle may deposit a strong charge on the vehicle, and if the metal gas nozzle then touches the car body, the spark can ignite the fuel vapors. During refuelling of aeroplanes, friction between the fuel and the hose causes static electricity. A wire can be used to discharge it safely, much like a lightning conductor, and the use of this grounding wire is mandated on fuel trucks at airports.

Also there are two safety hazards involving electrostatic generators used in science classrooms.

The first involves heart fibrillation caused by capacitors or "Leyden Jars" being discharged across a victim's chest. If a VandeGraaff or Wimshurst machine is used to charge up a Leyden Jar with capacitance larger than about 100 picofarads, and if the victim touches the terminals with two opposite hands (so the current path is through arms and chest,) the large current can trigger a heart attack. This happens rarely, but the danger is always there.

The second involves heart fibrillation caused by discharging of a "human chain." If a large group of students holds hands while one student touches an electrostatic generator, the chain of students becomes charged. If one student then touches a grounded water pipe or electric outlet, the current through that student's chest can be more than enough to trigger a heart attack.

Also, there are solid state (semiconductor) devices, such as CMOS components, that are particularly vulnerable to electrostatic discharge. This can involve humans in that any persons with implanted medical devices which extend through the skin (such as Cochlear Implants) and which use CMOS electronic components, might destroy their expensive devices by causing an arc from their body to a metal object. 2. One of the most hazardous places electrostatic charge can be is in the fireworks, munition factories and solid space rocket booster factories. Before the final products are produced there is mixing of firing explosives in motors for fireworks rockets. Gun powder can also be ignited by a spark from an electrostatic discharge. These factories are extremely dangerous in that there is a large amount of these explosives stored on location.