Incident Overpressure: the overpressure associated with the
incoming blast pressure wave unimpeded by solid objects.
Incident overpressure is sometimes referred to as side-on or free
Insulating Glass Unit: two glass lites separated and joined by a
perimeter spacer which seals the enclosed airspace.
Interlayer: a material specifically developed for bonding glass
lites, polycarbonate lites, or glass and polycarbonate lites
Interlayer Thickness: the thickness of the plastic interlayer
(e.g., 0.030, 0.060, or 0.090 inch).
Laminate: composite unit of glass or polycarbonate and interlayer
Laminated Glass: two (or more) plies of glass bonded together
with a PVB interlayer.
Lite or Light:
a single piece of glazing material, monolithic or
a single piece of glass.
Negative Impulse: the brief period of partial vacuum which
follows the pressure increase at the beginning of the blast
pressure wave. The negative impulse is the product of the
negative pressure (vacuum) and its duration.
Negative Phase Duration: the length of time during which the
explosion creates a partial vacuum at a particular point.
Non-Symmetrical: construction of a glass-clad polycarbonate such
that the cross-section is not a symmetrical distribution of type
and thickness of glass, polycarbonate, and interlayer.
Overpressure: the increase in atmospheric pressure at a point
when the blast pressure wave arrives at that point.
layer of material in a laminated glazing construction.