Eurotubi Pressfitting System - Technical Guide ... - Damstahl

12. PIPE CALCULATION
12.1. Pressure drops
Water or gas, which flow in the pipes, gradually lose their own pressure, because of the different resistances
they meet on the course. These resistances are due both to straight pipe resistance or to single casual
conditions as direction changes, section reductions, etc. Therefore the whole of pressure drops for a pipe
system is calculated according to the following formula:
where:
∆p= ∆p1 + ∆p2
∆p
∆p1
∆p2
is the total pressure drop;
is the pressure drop due to straight lengths;
is the pressure drop due to single localized resistances.
12.2. Pressure drops of a straight pipe
The following formula is used to calculate pressure drops, due to straights lengths
where:
∆p1 =ΣR • l
ΣR is the result of R1 • I 1 + R 2 • I 2 + ... + R n • I n ;
R is the unitary pressure drop expressed in mbar o in Pa/m;
l is the straight pipe length in m.
As well, the following formula is used to calculate the unitary pressure drop:
where:
R = λ • ρ • v 2 /(2 • d)
λ is the pipe friction coefficient;
ρ is the fluid density expressed in kg/m 3;
v is the fluid speed expressed in m/s;
d is the internal pipe diameter in mm.
For a practical calculation of pressure drops it is possible to refer to the following tables.
12.3. Pressure drops of single localized resistances
The following formula is used to calculate pressure drops due to single localized resistances.
∆p2 = ΣZ