Static electricity from flowing liquids

Section 5.4.1 described explosions in storage tanks, and Section 13.3 described explosions in tank trucks, ignited by static sparks. The static was formed by the flow of a nonconducting liquid, and the spark discharges occurred between the body of the liquid and the grounded metal containers (or filling arms). 

If a conducting liquid such as acetone or methanol flows into an ungrounded metal container, the container acquires a charge from the liquid. and a spark may occur between the container and any grounded metal that is nearby, as in the following incidents. 

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. 

Even if the bucket had been grounded, it would still have been bad practice to handle a flammable (or toxic or con osive) liquid in an open container. It should have been handled in a closed can to prevent spillages (see Sections 7.1.3 and 12.2 c). Closed cans, how- 

Note that, as in the incident described in Section 13.3, the operation had been carried out a number of times before conditions were right for an explosion to occur. 

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