Burkert Type 8630 - Manual (Page 27)

8630 - 25
S
YSTEM
D
ESCRIPTION
* Operation as a flow rate controller (option)
The flow rate controller is a special type of process controller. The process value (PV) is not measured
directly via an analog input but calculated in the device by the dp method. According to the algorithm,
the flow rate is dependent on the parameters
pressure before valve (p1), pressure after valve (p2), me-
dium temperature (T) and the kv value. For this reason, the TOP Control Continuous FMR has inputs
for 2 pressure transmitters and a temperature transmitter which can be optionally connected.
One pressure transmitter measures the pressure before the valve and a second one after the valve. The
temperature is either entered manually in the operating menu or is provided as a standard signal by a
temperature transmitter. The kv value is determined internally from the current position of the control
valve. For this purpose, a kv characteristic curve is provided in the control valve used.
The density of the medium is entered via the operating menu.
In the case of the flow rate controller, the process parameters are either the volumetric flow rate or, for
special applications, the transport velocity at the end of a pumping section.
The volumetric flow rate is represented in m 3 /h STP, i.e. referred to 0 °C (medium temperature) and a
gas pressure of 1013 mbar (abs).
There are special applications for flow rate controllers in which a pumping section is set up after the
valve, in which bulk goods enter via an airlock. These bulk goods are blown through the pumping
section by the pumping pressure that builds up behind the valve.
The transport velocity corresponds to the volumetric flow rate of the medium, referred to the piping
diameter of the pumping section. However, it is not specified for standard conditions, but reflects the
velocity of the gas particles at the existing medium temperature. The diameter is entered in the
operating menu.
Characteristics of the flow rate controller software
The flow rate controller offers the same functions as the process controller.
8630
Flow rate
controller
e.g. valve
type 2712
PV
kv value
Pressure
Temperature (optional)
T
p1 p2
Pressure
p1 p2