Datasheet

12
463
Cv
f kv Kv
S
CQ
n
18
270
5
S
mm
2
kv
dm
3
/min
Kv
m
3
/h
Cv
USG/min
f
gal/min
Q
n
l
n
/min
S 1 0.794 0.048 0.055 0.046 54.53
kv 1.259 1 0.06 0.07 0.058 68.65
Kv 20.979 16.667 1 1.166 1.035 1 144
Cv 18 14.3 0.858 1 0.829 981.5
f 21.7 17.243 0.967 1.206 1 1 184
0.055
16.67
0.06
0.015
68.65
0.2
54.53
0.07
14.3
0.018
0.001
981.5
0.794
1.259
1.206
0.829
0.0037
Subject to change
SI UNITS, SYMBOLS AND DIMENSIONING
I
n order to determine if a valve has sufcient output for
a given application, requires more than knowing the
maximum ow. You must also know how a value is
measured in order to use it in the actual case.
A valve ow performance depends not only on the
dimensions and geometry of the valve body. The follow-
ing variables are signicant:
■ The pressure at the output port
■ The pressure drop across the valve
■ The relationship between this pressure
and the primary pressure
■ The temperature
In all cases, based on a data ow performance on the
so-called normal volume. It is the volume of air occu-
pied at atmospheric pressure, 20 °C and relative humid-
ity of 65% (normal air). This volume is frequently given in
l
n
resp Nm
3
. Since newton (N) has been introduced as a
unit of force, this writing is no longer correct. Since liter
is not an SI unit, volume should be given in dm
3
n
, and
since that unit is unnecessarily complicated, we have
chosen l
n
for simplicity.
In the adjacent chart is shown the international use of
the units and their interrelationships. The arrows point-
ing to another unit states the conversion factor.
Q
n
– normal ow rate
To roughly indicate ow, volume is currently used, i.e.
the ow that the valve is performing at a primary pres-
sure of 6 bar and 1 bar pressure drop across the valve.
It is only a rough indication, because the measurement
methods and conditions may vary from make to make.
S – equivalent ow area
The value of S in mm
2
is the ow area (holes) in a meas-
uring instrument that provides the same pressure drop
as a valve or a system of components at the same out-
put. SMC species this value for each component. It is
measured with air as a medium and can be converted to
other units, such as kv or Cv factor.
Units for ow
Comparison and conversion between
different international ow units.