Geberit Silent-db20 - Deflection Leg - Guidance on Use

40
Geberit Drainage Systems
System installation
Compensating thermal expansion by deflection leg.
Determining the length of the deflection leg by calculationDetermining the change in length
A deflection leg is a length/section of pipe specified within the system to accommodate the movement as a result of
thermal movement. Deflection legs for pipe lengths of greater than 15m are not recommended as the bending leg will
be larger than the maximum bracket spacing.
Length of the deflection leg (DL) in mm according
totheformula:
The change in length is determined with the
followingformula:
ΔL:Changeinlength
L:Pipelength[m]
ΔT:Temperaturedifferential(operatingtemperature–
ambienttemperatureatimeofinstallation)[K]
α:Coefficientofthermalexpansion0.17mm/[m·K]
Example:• α =0.17mm/(m·K)
• L=6m
• ΔT=50K
ΔL=6x0.17x50=51mm
5.2.2 Deflection Leg - Guidance on use
+70ºC
+51 -41
6m
G
G
A
DL
Guide bracket
Anchor bracket
Deflection leg
GA
A
DL
+20
ºC -20ºC
10x
∆L x Ø
Example:DL=10x51x110=749
DL = 10 x 41 x 110 = 672
ΔL = L · α · ΔT