There was additionally confusion because of the contradictory instructions coming from the emergency communication system, the fire alarm instructing students to evacuate while the PA system instructed them to lock down and stay the place they had b Underground set up is often straight and in line, whereas above-ground installation allows for a more compact set up to save space. A DCVA, unlike a PVB, does not need to be positioned no much less than a foot above the best downstream level w...