CEA 4001 - Page 187

187
P
P.6.3
Galvanized pipes shall not be used for pipe-work filled with water foam mixture or used in foam
concentrate lines unless proof of the compatibility of the foam agent with galvanized pipes is available.
P.6.4
A filter or strainer shall be fitted upstream the foam injection device. Maintenance and cleaning of
the filter shall not affect the operation of the extinguishing system (by pass around the strainer).
Filters are not necessary if a sphere with a diameter of 8mm can pass all ways of foam through
pressurized tanks, foam injection devices,….
P.7 Calculation of the friction loss of foam agent pipes
P.7.1 The calculation shall be done for the lowest and highest viscosity (only highest viscosity for
Newtonian liquid) of the foam agent.
This calculation shall be based on the foam demand corresponding to the sprinkler design flow.
The friction loss in the foam pipes shall be calculated with the Darcy formula
)aluormf(Darcy
2
2
 ' v
d
L
p
U
O
With:
'
p
friction loss, in N/m
2
O
friction number
L pipe length, in m
d pipe diameter, in m
U fluid density, in kg/m
3
v flow velocity, in m/s
The friction number
O
shall be determined depending on the Reynolds number Re using the following
formula.
Reynolds number:
J

Y
G5H
With:
J
kinematic viscosity, in m
2
/s
For the determining of the Reynolds number the Kinematic viscosity at the lowest temperature at the
foam tank shall be used.
For Re < 2350 (laminar) is: