The integrated diaphragm unit (pos. 1a) maintains the diffe-
rential pressure "p1" - "p2" at a constant level not only across
the regulating unit (pos. 2) activated by the actuator but also
across the nominal value unit which can be set to a maximum
flow value (pos. 1b).
Even were high differential pressure variations "p1" - "p3" oc-
cur, e.g. if sections of the system are activated or inactivated,
the differential pressure "p1" - "p2" is kept at a constant level.
This way, the valve authority of the "Cocon QFC/QGC" valves
amounts to (a=1). Even during low demand periods with stea-
dy control (e.g. in conjunction with 0-10 V actuators), the valve
authority within the effective valve lift amounts to 100% (a=1).
2.9
Differential pressure p1 - p 3 [psi]
Illus. 7 Flow characteristic line for different presetting
.
The maximum flow rate (V) within the control range (2.9 -
58 psi) is set with the help of the handwheel. During low
demand periods, the flow rate is regulated to the required
valve by the lift position of the regulating valve.
The combined control and regulating valve "Cocon QFC/
QGC" has a linear characteristic line within the active valve
lift. This is advantageous when using actuators which also ha-
ve a linear stroke behaviour.
100
0
Flow volume V [l/h]
Illus. 8 Characteristic line of the valve "Cocon QFC/QGC"
5.2 Markings
Details of the CE marking on the valve handwheel
CE marking
Information on the valve body:
OV
Manufacturer
DN
Nominal size
PN
Nominal pressure
GJL250 / GG25
Valve body material
D in mm
outer diameter D of groove connection
5.3 Application
Oventrop combined control and regulating valves "Cocon
QFC/QGC" are used for flow control in central heating and
chilled ceiling systems with circulation pump. Room tempera-
ture control can e.g. be carried out by use of room thermost-
ats and actuators.
4
Lift position of the
Position of the
58
regulating valve
handwheel
max
.
6 Installation
Before installing the valve, the pipework has to be flushed
thoroughly. Installation is possible in any position (horizontal,
oblique or vertical, in ascending or descending sections; elec-
tric actuators may not be installed vertically downwards – the
installation instructions of the actuator are to be observed). It
is important to note that the direction of flow must conform to
the arrow on the valve body and that the valve must be instal-
led with L = 3 x Ø of straight pipe in the upstream side and
with L = 2 x Ø in the downstream pipe. Any tension which
could be transferred through the pipework must be avoided.
After installation, the handwheel and measuring connection
must be easily accessible.
Once installation is completed, check all installation points for
leaks.
7 Operation
7.1 Deaeration of the system
Before initial operation, the system has to be filled and bled
with due consideration of the permissible working pressures.
7.2 Setting of the flow rate
The max. flow volume can be set with the help of the protec-
ted presetting at the handwheel (see illus. 3).
7.3 Control by use of actuators
To control the heating/cooling system during part load condi-
tions, actuators must be mounted onto the "Cocon
QFC/QGC" valves, which will vary the flow rate depending on
the controlled variable (e.g. room temperature).
7.4 Isolation
The valve can be isolated manually by turning the presetting
to the right until stop.
7.5 Correction factors for mixtures of water and glycol
The correction factors of the antifreeze liquid manufacturers
have to be taken into consideration when setting the flow rate.
8 Accessories
To determine if the valve operates within the control range,
Oventrop offers two measuring gauges:
Oventrop measuring system "OV-DMC 2"
Oventrop measuring system "OV-DMPC"
The combined control and regulating valves "Cocon QFC/
QGC" can be used with the following Oventrop actuators:
1158010 Actuator with squeeze connection
24V, steady 0 - 10V
1158030 Actuator with squeeze connection
24V, steady 0 - 10V and 4 - 20mA
1158031 Actuator with squeeze connection
24V, steady 0 - 10V and 4 - 20 mA,
with additional spring return
The accessories can be found in the catalogue.
9 Maintenance
The valve has to be serviced if it malfunctions.
10 Warranty
Oventrops warranty conditions valid at the time of supply are
applicable.