Dometic 39726.501, 39726.506, 39626.501, 39626.506 installation instructions Rr = R, CR = R a

INSTALLATION INSTRUCTIONS

PREFERREDFAIR (Standard)

POOR NOT ACCEPTABLE

Various Elbows Showing Radius Ratios

FIG. 2.3

E D D I E S
ITEM 1	ITEM 4
Sharp Angle	Long Radius Bend

E D D I E S
ITEM 2	ITEM 5
Rounded	Splitters, or turning vanes
Outer	installed in sharp angle
Corner	bend

R

D

RR = R

WW

Radius Ratio (RR)

or RR = 1.5

FIG. 2.4

R b

			D
	R a	CR = R a
W			R b
	Curve Ration (CR)
	Optimum Reading CR = .05
	FIG.	2.5
		CR =	Ra
			Rb
	R1	R1 = 2 Ra
		CR = .25
R b	R a
		CR =	Ra
			Rb
	R1	R1 = 2 Ra
			(Rb - R1)
		R2 =
R2			2	+ Ra
R b		CR = .15

R a

FIG. 2.6Using Splitters to reduce resistance.

	ITEM 6
ITEM 3	Splitters in rounded
Rounded	corner bend
Corners

FIG. 2.7

Different ways of making a 90 degree bend. Some

involve greater pressure losses than others.

LARGE DUCT	ABRUPT
	CONTRACTION

E D D YSMALL

LOSSES D U C T

FIG. 2.8

Pressure losses occur with abrupt reducing fittings.

ABRUPT EXPAN-

S I O NLARGE D U C T

SMALL

D U C T

E D D Y

LOSSES

FIG. 2.9

Abrupt expansion results in excessive pressure losses.

6