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Back in the olden days, fuel trucks had a chain suspended from the axle to the ground to dissipate the explosive static charging fuel will buildup from sloshing around inside a tanker.

I remember them being banned, but what replaced the chains?

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    \$\begingroup\$ I'm voting to close this question as off-topic because it has nothing to do with the design of electronics circuits as supported at this site. \$\endgroup\$ – Michael Karas Apr 28 '15 at 5:57
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    \$\begingroup\$ I am apposed closing this. The question revolves around dissipating static charge and how it is accomplished in fuel tankers , specifically in transit( or that is what I understand). \$\endgroup\$ – Password Apr 28 '15 at 6:51
  • \$\begingroup\$ The question can be rewritten as: "How do they design the static charge dissipation circuit in modern fuel carrying trucks and how did they do it in the past"? Joking aside, I think it is related to electrical engineering, as a question about grounding. \$\endgroup\$ – WalyKu Apr 28 '15 at 7:25
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    \$\begingroup\$ @MichaelKaras It says "Electrical engineering" at the top of the page, not "design of electronic circuits." \$\endgroup\$ – David Richerby Apr 28 '15 at 8:48
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    \$\begingroup\$ This is relevant to "electrical installations in hazardous areas", a dedicated sub-field of electrical engineering. The engineering company I work for does a lot of this (There are about a dozen drawings on my senior engineer's desk, right now, detailing earthing arrangements for petrol stations.) Question is on-topic. \$\endgroup\$ – Li-aung Yip Apr 28 '15 at 9:08
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The process of grounding the tanker is still carried out. The first thing they do before unloading the fuel is ground the tanker to earth in order to discharge all the static charge through a safe path. This process of governed by various standards of operation. An example of the grounding setup looks like the following:

enter image description here

Source: http://www.newson-gale.com/knowledgebase/ettg22/tank_truck_grounding_1.asp

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    \$\begingroup\$ Note that the grey device is most likely a surveillance unit that sounds an alarm if earthing is not properly done. When working with cereals these devices are mandatory in certain legislations, not sure about gas tanks (given that in a lot of countries not even fume extractors are mandatory...) \$\endgroup\$ – PlasmaHH Apr 28 '15 at 9:04
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    \$\begingroup\$ Interesting. Still doesn't address completely what the OP asked. In particular it doesn't explain why there seems to be no need to discharge the tanker while it is moving, as the chain supposedly was there for. BTW, I don't know the answer for this. \$\endgroup\$ – Lorenzo Donati supports Monica Apr 28 '15 at 13:06
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    \$\begingroup\$ I dont know why the were doing it in the first place, logically it makes no sense. The tanker is insulated from the ground because of its tires and hence cant discharge. Furthermore the charge distribution should only be on the outside acting like a Faraday cage, so the only risk of an ignition is when the fuel is being unloaded. (The only time it may discharge is if the potential is large enough to lead to the dielectric breakdown of air which is a lot of charge (30KV/cm). \$\endgroup\$ – Sada93 Apr 28 '15 at 13:11
  • \$\begingroup\$ @PlasmaHH Good point, a flour or grain dust explosion can wreck one's day quite easily... \$\endgroup\$ – Reinstate Monica Apr 30 '15 at 15:12
  • \$\begingroup\$ @Sada93: they made it because it was the cheapest solution, and regulations didn't demand anything more sophisticated. And as long as they are still there, you can not forget to put them on or do it in a wrong way. \$\endgroup\$ – PlasmaHH Apr 30 '15 at 15:17

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