Technical data

14
Compressed Air Applications Manual | Selection of material and pipe system
The dimensioning of polybutene pipes
under internal pressure is carried out
strictly on the basis of the strength
requirements using the compressed-air
receiver formula:
p x d x SF
s =
(20 x δB) + (p x SF)
The above formula is used for all
the pipe dimensions laid down in the
standards.
In order to be able to select pipes,
fittings and valves according to uni-
form criteria, they are divided into
standardized pressure classes. A
common method applied worldwide
is the classification on the basis of
nominal pressure (PN).
Here, the nominal pressure (PN)
indicates the permissible operating
pressure at 20 °C.
Nominal pressure PN 16 means that a
pipe of this pressure class can be sub-
jected to a pressure of 16 bar at a tem-
perature of 20 °C.
Therefore, the nominal pressure class
is not the decisive criterion. What really
counts are the demands on the material
at an operating pressure of 10 bar and
a temperature of 70 °C, assuming a 50-
year service life and including a safety
factor of 1.5.
Determination of pipe wall thickness and pressure class
s = pipe wall thick-
ness
p = operating pres-
sure at 20 °C
δB = comparative
stress
SF = safety factor
Keydata of BEKOFLOW
®
PB pipes
Inch Nominal
dia.
DN
Outside pipe
dia.
d
Pipe wall
thickness
s
Inside pipe
dia.
di
Weight per m
pipe
kg
Water volume
per m pipe
l
⅜
½
¾
12
15
20
16
20
25
2.2
2.8
2.3
11.6
14.4
20.4
0.088
0.141
0.152
0.10
0.16
0.33
1
1¼
1½
2
25
32
40
50
32
40
50
63
2.9
3.7
4.6
5.8
26.2
32.6
40.8
51.4
0.254
0.392
0.610
0.969
0.53
0.83
1.31
2.07
2½
3
4
65
80
100
75
90
110
6.8
8.2
10.0
61.4
73.6
90.0
1.354
1.960
2.920
2.96
4.25
6.36
Measurements in mm
Pipe roughness factor k = 0.007
For PB according to DIN 1988
BEKOFLOW
®
PB pipes
are manufactured to
DIN 16968 und 16969.