Charge accumulation

In order for static electricity to be a source of ignition, four conditions must be fulfilled 

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As metal ion concentration increases in the crevice, a net positive charge accumulates in the crevice electrolyte. This attracts negatively charged ions dissolved in the water. Chloride, sulfate, and other anions spontaneously concentrate in the crevice (Figs. 2.4 and 2.5). Hydrolysis produces acids in the crevice, accelerating attack (Reactions 2.5 and 2.6). Studies have shown that the crevice pH can decrease to 2 or less in salt solutions having a neutral pH. 

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... 

NFPA 30 also fails to recommend flow rate restrictions except a slow start until the downspout is submerged. Section 5-4 of this book provides for restricted flow rates throughout filling this should be applied wherever charge accumulation is possible due to low liquid conductivity and where flammable mixtures involving gas, mist or froth may be formed. 

Nonconductive plastic pipe should not be used for transfer of ignitable powder or for any powder transfer through electrically classified areas. Hazards comprise brush discharges, PBDs and external sparks due to induction. Charge accumulation is discussed in 5-3.2.1. 

The total energy, E, is obtained from the total charge accumulated in both sections of the anode. The second part of the ionization chamber, which measures the energy E - AE, can be replaced by an SBD [3.167], and the first part, which measures the energy loss AE, by a transmission SBD [3.168, 3.169]. When SBDs are used to measure heavy ions, radiation damage of the detector by the ions must be taken into account. 

Substituent constants calculated in this way are in good agreement with empirical Of values. The same system was used to calculate values by determining charge accumulation or depletion on the a and p carbons of substituted ethylenes using the 4-3IG method. 

The handle of the bucket was covered with plastic. When acetone was drained into the bucket, a static charge accumulated on the acetone and on the bucket. The plastic prevented the charge from flowing to earth via the drain pipe, which was grounded. Finally a spark passed between the bucket and the drain valve, and the acetone caught fire. 

As with tanks (Section 5.4.1), explosions can also occur in grounded drums containing liquids of low conductivity if a static charge accumulates on the liquid and passes to a grounded conductor, such as a filling pipe. Reference 4 describes some incidents that have occurred. They are most likely when ... 

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