Fenestration, IG & Glazing Glossary
A - B - C - D
- E - F - G - H
- I - J - K - L - M
- N - O - P - Q - R
- S - T - U - V - W
- X - Y - Z
Active Solar Heat
Gain
Solar heat that passes through a material and is captured by mechanical
means.
Air Space
Refers to the space between the two lites of glass in a IG unit. Air space
is usually 1/32" greater than spacer width.
Adsorbent
A highly porous solid with the ability to concentrate and hold gasses
and vapors in contact with the solid. This includes moisture, as well
as many other organic and inorganic molecules.
Adsorption
The adhesion in an extremely thin layer of molecules (as of gases, solids,
or liquids) to the surface of solid bodies or liquids with which they
are in contact. Adsorption is the result of attractive forces that can
be likened to tiny "magnetic" microelectric charges on the surface
of the adsorbent and the adsorbed substance. Variables affecting capacity
include polarity, temperature, molecular size, adsorbate concentration,
and type of adsorbent.
Argon Gas
An inert gas used to fill IG units as a replacement for air. Argon filled
IG units have better thermal and sound insulating qualities then air filled
units.
Bed or Bedding
The bead of compound applied between a lite of glass or a panel and the
permanent stop or sight bar of the sash or frame, and usually the first
bead of compound to be applied when setting glass or panes.
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Bead
A Sealant/compound after application to a surface of the spacer.
Beveled or Cap Bead
Bead of compound applied so as to have a slanted top surface so water
will drain away from the glass or panel.
Bite
The dimension by which the edge of a glass product is engaged into the
glazing channel.
Block
Rectangular, cured sections of neoprene or other approved material, used
to position the glass product in the glazing channel.
Bow
Refers to any curve in the spacer. These could be up, down, or sideways
curves.
Breather (Tube) Units
An insulating glass unit where a tube or a hole is factory placed into
the unit's spacer to accommodate elevation of pressure differences encountered
in shipping. These tubes or holes are to be sealed on the jobsite prior
to unit installation.
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BTU
An abbreviation of British Thermal Units that defines the amount of heat
needed to raise the temperature of one pound of water one degree Fahrenheit.
Butt Glazing
The installation of glass products where the vertical glass edges are
without structural supporting mullions.
Butyl
A sealant which is used to adhere the glass to the spacer in an IG unit.
Capillary Tube Units
An insulating glass unit where a very small metal tube of specific length
and inside diameter is factory-placed into the unit's spacer to accommodate
both the pressure differences to the point of installation and also the
pressure differences encountered daily after installation. Capillary tubes
are not sealed after installation.
Cavitywall
A type of building wall construction consisting of an outer wall fastened
to an inner wall separated by an air space.
Certified IG Unit
An insulating glass unit constructed like a unit test model which has
successfully passed the ASTM E773 and E774 tests of insulating glass seal
durability performance at specific levels.
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Channel Glazing
The installation and sealing of glass products into U-shaped glazing channels
employing removable stops. Usually associated with a sealant, it is a
measure of the structural strength of the sealant material (tensile strength).
Cohesive Failure
The splitting and opening of a sealant/compound within its body, resulting
in structural damage and/or water penetration.
Condensation
The visible formation of moisture on the inside (room side) surface of
a IG unit.
Conduction
The transfer of heat through matter, whether solid, liquid, or gas.
Convection
A transfer of heat through a liquid or gas when that medium hits against
a solid surface.
Corner Flare
(As applied to a folded INTERCEPT spacer) is an increase in spacer width
at the corner bend point; caused by the corner punches on the Feeder Press
being set incorrectly (the folded spacer should have no corner flare on
any of the corners).
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Corner Gap
(As applied to a folded INTERCEPT spacer) is the space between the two
adjacent corner edges; it should be a minimum of .030".
Dead Loads
Load force due to glass weight.
Desiccant
A substance that adsorbs and holds moisture and organic and inorganic
molecules. It is used to adsorb air space moisture and prevent condensation
between the lites.
Dew Point
The temperature above 32°F at which visible water vapor or other liquid
vapor begins to deposit on the air-space glass surface of a sealed insulating
glass unit in contact with the measuring surface of the dew-point apparatus.
Double Glazed Units
Units of two lites of glass and one air space.
Dual Sealed Unit
Sealed insulating glass unit fabricated with an inner primary seal and
an outer secondary seal. Generally, each of the two seals has been selected
for its special performance characteristics, i.e.: adhesion and moisture
vapor transmission properties.
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Desiccant Station (stand)
The machine that applies the hot melt matrix to an Intercept spacer. It
also controls the application time delays on the Extruder.
Emittance
Heat energy radiated by the surface of a body, usually measured per second,
per unit area.
Equivalent Combined Glass load
Combination of the instant applied load of wind and the factored long
term loading of glass weight and snow accumulation.
Exterior Glazed
Glass set from the exterior of the building.
Extruder
Machine which applies the sealant to a spacer.
Extrusion
An application of sealant or matrix.
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Face Glazing
On a rabbetted sash without stops, the triangular bead of compound is
applied with a glazing knife after the bedding setting and clipping the
lite in place.
Failed IG Unit
An installed unit failure exhibits permanent material obstruction of vision
through the unit due to accumulation of dust, moisture or film on the
internal surface of the glass. Surface numbers 2 or 3 in dual-pane units;
surface numbers 2,3,4 or 5 on triple-pane units.
Feed Hold
Puts the Intercept in a pause condition, there are two types, "feed
press feed hold" and "system feed hold".
Feeder Press
The station on the Intercept Spacer Frame Machine that punches or stamps
Intercept™ spacer material to make corners, grid punches, tabs (lead
corners), gas and rivet holes. It is also referred to as the punch station,
punch press, or feed press.
Feeder Press Feed Hold
The only feed hold that deactivates the air cylinders on the feeder press.
The button is located on the feeder press itself.
Float Glass
Transparent glass with flat, parallel surfaces formed on the surface of
a pool of molten tin.
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FRL
(Filter/regulator/lubricator), Regulates the pressure of the air supply,
filters dirt and moisture from the air supply, and lubricates the air
lines and cylinders.
Flying Cut-Off
(FCO) The station on the Intercept Spacer Frame Machine that parts and
swedges the Intercept™ spacer.
Full Loop
Refers to the point at which the material strip is furthest from the loop
control sensor.
Fully Tempered Glass
Transparent or patterned glass with a surface compression of not less
than 10,000 psi or an edge compression of not less than 9,700 psi.
Gas-Filled Unit
Insulating glass unit with a gas other than air in the air space to decrease
the unit's thermal conductivity U-value and to increase the unit's sound
insulating value.
Gas Hole
A hole punched approximately 1" from the beginning of the last side
of the Intercept™ spacer. It is used to fill the unit with argon
or krypton.
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Gasket
Pre-formed shapes of rubber, or rubber-like composition, used as the weather
seal. Also, a spacer for supplemental application of a sealant.
Glazing
The installation and weather-sealing of a glass product in a prepared
sash opening.
Glazing Bead
A strip surrounding the edge of the glass in a window or door; applied
to the sash on the outside, it holds the glass in place.
Heel Bead
Compound applied at the base of channel, after setting lite or panel,
and before the removable stop is installed, its purpose being to prevent
leakage past the stop.
Heat-Absorbing Glass
Glass (usually tinted) formulated to absorb an appreciable portion of
solar energy.
Heat Strengthened Glass
Transparent or patterned glass with a surface compression of not less
than 3,500 psi or greater than 10,000 psi, or an edge compression of not
less than 5,500 psi.
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Hot Melt
Refers to any sealant or matrix that must be heated to extrude. It is
also used to describe the process of sealing units through a oven/roll
press.
Insulating Glass
(IG, Insulated Glass) Two lites of glass sealed together with an air space
between them.
Intercept
(Intercept Spacer Frame Machine) A machine which manufactures Intercept™
IG spacer frames.
Intercept™
The registered trademark for an insulating glass unit designed by PPG.
The design is based on a one-piece spacer frame that gives manufactures
the ability to make a warm edge insulating glass unit.
Interior Glazing
Glass set from the interior of the building.
Laminated Glass
Two or more lites of glass bonded together with a plastic interlayer.
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Leading Edge
(Leading corner; tab) The lead end of the Intercept™ spacer, it
inserts inside the trailing end of same spacer.
Light Reducing Glass
Glass formulated to reduce the transmission of visible light.
Lip
The top portion of the Intercept™ spacer; measured from the side
of the spacer in. The lip should measure from .070" to .083".
Lite
A piece of glass that is used in making a IG unit (two or more lites per
IG unit).
Live Load
Load force due to weight of non-permanent attachments; people, glazing
rigs, washing rigs.
Low Emissivity Glass
Glass with a transparent metallic or metallic oxide coating applied onto
or into a glass surface which reflects long-wave intrared energy and thus
improves the "U" value.
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Matrix
Is a mixture of hot melt adhesive and powder desiccant. Called holt melt
matrix, it's the form of desiccant used in the Intercept™ spacer.
Metal Spacers
Roll-formed metal shapes used at the edges of an insulating glass unit
to provide the desired spacing of the glass. Metal spacers allow areas
for sealant applications and contain desiccants.
Multiple-Glazed Units
Units of three glass lites (triple glazed) or four glass lites (quadruple
glazed) with two and three air spaces respectively.
Muntins
(Grids) Bars used to divide IG units into geometric lites, they are permanently
mounted between two lites. Similar to mullions but smaller in dimensions
and weight.
Mullion
A horizontal or vertical member that holds together two adjacent lites
of glass or sashes, or curtain wall sections.
MVT
Moisture vapor transfer; is the rate at which moisture passes through
the seal of an IG unit.
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Needle Glazing
Application of a small bead of sealant/compound at the site line by a
nozzle gun.
Passive Solar Heat
Gain
Solar heat that passes through a material and is captured naturally, not
by mechanical means.
Patterned Glass
Rolled glass having a distinct pattern on one or both surfaces.
Permeability
The time rate of water vapor or gas transmission through a unit area of
the material unit thickness induced by unit vapor pressure difference
between two specific surfaces under specific temperature and humidity
conditions.
Permeance
The time rate of water vapor or gas transmission through a unit area of
a body, normal to specific parallel surfaces, under specific temperature
and humidity conditions.
PIB
(Polyisobutylene) A substance normally used as the primary seal of a dual
seal unit.
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Pre-Shimming
A preformed tape continuing a built-in continuous elastomer rod to eliminate
use of individual shims which can be inadvertently omitted.
Primary Sealant
A sealant applied to the inner shoulders of a spacer with its principle
purpose to minimize moisture, gas and solvent migration into the unit's
air space.
Profile
Refers to the height of the spacer material; standard, low or ultra low
are most common.
Purlins
Structural members, generally horizontal, in slope glazing frames.
R-value
The overall resistance to heat transfer. The R-value is the reciprocal
of the U-value.
Rabbet
A two-sided L-shaped recess in a sash frame to receive glass products.
Addition of a removable stop will convert it to a glazing channel.
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Racking
Movement and distortion of sash or frame because of lack of rigidity,
or can be caused by adjustment of ventilator sections. Puts excessive
strain on the sealant and may result in joint failure.
Rectangle Spacer
(Box) Spacer material used in the linear process; utilizes folding corner
keys.
Reflective Coated Glass
Glass with metallic or metallic oxide coating applied onto or into the
glass surface to provide reduction of solar radiant energy, conductive
heat energy and visible light transmission.
Rivet Hole
Holes located at the tab and the end of the Intercept spacer; they align
when the tab is inserted in the opposite end.
Roll Former
The station on the Intercept Spacer Frame Machine that forms the U shape
spacer out of the flat coil stock.
Sealant
Refers to material that joins the two lites of glass to a spacer forming
a IG unit.
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Sealant Spacer
A permanent adhesive sealant extrusion which may contain a structural
metal insert and a precompounded desiccant.
Sealed Insulating Glass Units
Units constructed of two or more lites of glass separated and hermetically
sealed to spacer frames at the glass edges with the enclosed air chamber(s)
dehydrated at the plant's atmospheric pressure.
Secondary Sealant
A sealant applied into the exterior glass-spacer cavity to provide elastic,
structural bonding of the assembly. In single-sealed units, this sealant
also has low gas and moisture vapor transmission property to achieve effective
unit performance.
Setting Blocks
Rectangular, cured extrusions of neoprene rubber or other approved material
on which the glass product bottom edge is placed on glazing to effectively
support the glass weight.
Shear
Strain put on a compound between two surfaces when there is a slipping
movement of the two surfaces, parallel to and in opposite directions along
the length of the joint, such as occurs when an aluminum channel expands
to a greater length than a glass panel when both are subjected to the
same pronounced rise in temperature. This kind of strain tends to rub
or knead the compound in opposite directions along the joint, as contrasted
to other forms of strains which may try to pull the compound apart, by
reason of the strain being at a right angle to the joint.
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Shore A Hardness
Measurement of the hardness of a cured elastomeric material by means of
a durometer hardness gauge. Range of 20-25 is about the firmness of an
art gum eraser. Range of 40-50 is about the firmness of a rubbr heel.
Sight Line
Imaginary line around the perimeter of a glazed glass product defined
by the top edge of stationary and removable stops, or the line where the
glazing sealant or gasket contacts the glass.
Single-Sealed Unit
Sealed insulating glass unit where the structural bonding and moisture
sealing is accomplished by a single substance (sealant).
Sloped Glazing
Any installation of glass that is at a slope of 15 degrees or more from
vertical.
Spacer Corners
Specific methods used in joining the spacer lengths into spacer frames
including interlocking keys, bending, soldering, or welding.
Spacer Frame
The component that separates the lites of glass in an IG unit.
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Spacers (Shims)
Small blocks of neoprene, or other approved material, placed on each side
of the glass product to provide glass centering, maintain uniform width
of sealant bead, and prevent excessive sealant distortion.
Spandrel
That portion of the exterior wall of a multi-story commercial building
that covers the area below the sill of the vision glass installation and
above the head of the glass installation below.
Splay
The difference in spacer width comparing the width at the top of the spacer
to the width at the bottom of the spacer; it should not exceed .015"
total.
Stops
The stationary lip of the back of the glazing channel and removable molding
(retainer) at the front of the glazing channel.
Structural Glazing Gaskets
Cured elastomeric channel-shaped extrusions used in place of a conventional
sash to install glass products onto structurally supporting sub-frames
with the pressure of sealing exerted by the insert of separate lock-strip
wedging splines.
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Structural silicone Glazing
A system in which the glass product is bonded to the framing members of
a curtain wall utilizing a structural silicone adhesive/sealant without
the presence of outdoor retainers or stops.
Suspended Film Insulating Glass
IG unit manufactured with a light and energy controlling film suspended
within the air space.
Swedge
Preformed at the flying cutoff, it slightly reduces the tab width, which
makes the tab small enough to fit into the end of the spacer without forcing
the spacer to flare; it should measure .025" to .030" less than
the finished spacer width.
System Feed Hold
Puts the Intercept machine into a pause condition, continuing when feed
the hold button is pulled out. It can be initiated from all machine feed
hold buttons except the feeder press feed hold button. It can also be
activated from the flying cutoff guards and the semi-auto mode proximity
switch. A system feed hold does not deactivate the air cylinders on the
feeder press.
"T" Bar
Spacer type used in polysulfide and hand gunned hot melt applications.
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Tight Loop
Refers to the point at which the material strip is closest to the loop
control sensor.
Time Delay
Is the time between sensor activation and extrusion application. It is
set with the time delay switches on the desiccant stand.
Tin Plate
Refers to the plating on the steel. Tin plated steel is used for manufacturing
Intercept™ spacer frames.
Transducer
An electrical device used on loop controls to maintain the proper material
distance from the floor. It works by transmitting and receiving sound
waves, then emitting a signal to the uncoiler motor.
Twist
Deformation of the spacer. Both ends of the spacer turned in opposing
directions.
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U-Value
The amount of conductive heat energy (BTU's) transferred through a one-square-foot
area of a specific insulating glass unit for each degree Fahrenheit temperature
difference between the indoor and outdoor air. It is the inverse of the
R-value; U=1/R.
Warm Edge Technology
Is used to define thermal characteristics for the edge of glass region
of the IG unit in relation to heat loss as well as to condensation potential.
Weep Holes
Slots or holes in the sill (bottom) member of the sash frame to provide
outdoor release of infiltrated water.
Wet-Out
The area of seal created by the butyl to glass press after the butyl/glass
is heated and pressed. This is also called seal width or MVT path.
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