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Lightning Arrestor installation / Vapor area

Question asked by lsh0215 on Dec 10, 2018
Latest reply on Dec 10, 2018 by chriscarlson

Greetings,

 

In our facility, there is loading/unloading rack where thousands of trucks are coming per day to fill hydrocarbon product to their tanker. the rack has canopy with thickness is greater than 4.8mm (3/16 in). on top of the rack, there is a vent system to release pressurized vapor inside of the truck tanker before they fill the hydrocarbon.

 

According to NFPA 780 (ver 2017) para 7.2.1.1 openings where flammable concentrations of vapor or gas escape to the atmosphere shall be closed or otherwise protected against the entrance of flame. and para 7.2.2 inherent protection will allow when the structure is tightly sealed.

 

My question is that what if we install lightning arrestor close to the this vent pipe where the arrestor height is one meter higher than the vent pipe (see attached). If lightning strike hit this area, is this safe against lightning? or should we install flame arrestor on the vent regardless of lightning arrestor installation?

 

If vapor is exist at the vent pipe, lightning arrestor is able to protect the facility?

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