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 18.104.22.168 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?