Observation of Discharges

For a pipe C = 2jtIe e0 /lnOyVj) where / = length and r r2 = inner and outer radii. 

It is recommended that flammability always be assessed first, since it is inherently safer to avoid flammable atmospheres than to avoid sources of ignition such as static electricity. If a flammable atmosphere cannot be avoided at all times, the system should be designed to minimize both the probability and consequences of ignition. In this chapter it is assumed that static electricity is the only source of ignition however, in practical situations all sources of ignition such as those described in [ 157] should be evaluated. 

The potential to form a flammable atmosphere is addressed using methods discussed in Chapters 5 and 6. 

Decision trees are not used in this book since they are most useful when targeted to a specific process attempts to generate comprehensive matrices rapidly lead to extremely complex schemes. Instead, the book should be used to help generate suitable matrices or to supplement the decision-making steps in published matrices such as [ 199 ]. Many of the decision steps, such as the conditions under which discharges of some specified effective energy may occur, are not properly understood and continue to be controversial. 

Conductive objects may accumulate charge via conduction, induction, ion collection or contact-separation in relation to a nonconductor. In general, charge accumulation on conductive objects can be completely prevented by bonding and grounding. The only decisions to be made are how small the resistance to ground must be (4-1.3) and how small a conductive object needs to be before it can be neglected. The latter depends on the results of 

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