Brochure

92 Series, H and V Series Alternate Sizing Graph
Method of Determining Al-
ternate Grille Sizes
Extensive tests indicate that by varying dimensions of
a grille there is no appreciable effect on the air throw,
provided the same area is maintained. To change
the dimensions of a grille, place a straight edge
across the width and height scales on dimensions as
selected from charts. Place a pointer at the crossing
point on the turning line and rotate the straight edge
around this point until it crosses width and height
scale at dimensions desired.
NOTE: Grille sizes determined from this chart are the
nominal or duct dimensions.
General Conclusions on
Air Distribution
1. The throw from a straight flow grille varies with the
square root of the daylight area of the grille and
with the face velocity.
2. The ratio of the width to the height (aspect ratio) of
a grille has no appreciable effect on the distance of
air throw.
3. If the air streams from a grille are converged, it
results only in cutting down the effective area of the
grille.
4. Breaking the air stream up into jets has no effect
on either the rate of mixing or the flow.
5. Fanning out the air stream shortens the throw. The
amount depends on the degree of deflection.
6. The drop, for a given throw, of an air stream below
room temperature varies about inversely as the face
velocity and directly as the temperature differential.
7. For any given velocity neither the aspect ratio of
the grille, breaking the air stream up into jets, nor
impinging the air streams together equally have
any effect on the drop of the air stream.
Basic formulae determined through elaborate test work
and used in the compilation of the charts contained
herein are:
(1) T = Kt x CFM
√A x Vt
(2) CFM = V x Ak
(3) CFM = An x Vn
Where: T = Throw (feet)
Kt = Throw factor determined by test
CFM = Air flow rate (cubic feet per minute)
A = Core Area, sq. ft.
Vt = Terminal Velocity
Vk = Face Velocity (Feet per minute)
Ak = Effective area
Where: Vn = Neck Velocity in feet per minute
An = Neck area in square feet
For further definition see the glossary pg. 121
Listed Size 6 8 10 12
An (Round) .20 .35 .55 .79
An (Square) .25 .44 .69 1.00
Listed Size 14 16 18 20
An (Round) 1.10 1.40 1.80 2.20
An (Square) 1.40 1.80 2.30 2.80
Air Velocity (FPM) and Velocity Pressure (Pv, inches
water column) relationships:
Vel = 4005 √Pv
Pv = Vel
2
4005
CFM = BTUH
∆T x 1.085
( )
Grille Width
in Inches
Turning
Line
Grille Height
in Inches
120
Engineering Data
Engineering Data