Burkert Type 8750 - Manual (Page 24)

I
NSTALLATION
22 - 8750
Evaluation of the control results after commissioning of the system
After successful completion of PROCESSTUNE, the system runs with the FMR in the
automatic mode. With reference to the control results, an evaluation of the results obtained is
now made.
A) The control results correspond to the technical requirements. In this case no further
measures are required.
B) The control results deviate from expectations. In this case you should initiate measures
for improvement of the control behaviour.
Measures for improving the control behaviour
1. Carry out a linearization of the process characteristic with the routine P.Q'LIN and repeat
P.CO TUNE.
2. Correct the valve characteristic point by point, deviating from the characteristic shown in
the Kv-value table, which is stored in the program. On correction, the values originally
stored in the program memory are overwritten.
3. Select some other nominal width of valve seat from the Kv-value table or data sheet. For
this, the valve must be converted or exchanged.
Program function P.CO.LEAK (leak detection). Only for conveyor system’s
applications.
Boundary conditions for the reading-in of the leakage characteristic
For exact measurement of the leakage, the system should be started up in the normal mode.
However, the following exceptions apply:
•
The conveying pipe must be closed off behind the components causing the leak.
• The material to be transported is omitted.
Succession
• The control valve is closed.
• After 10 sec settling time, the admission pressure at the controller unit (FMR) is
registered.
• The control valve is slowly opened in a ramp time of 60 sec.
ATTENTION! • In the case of pneumatic conveying of pourable solids with a rotary
valve, the following must be observed:
• The conveying pipe must be closed off behind the rotary valve.
• The rotary valve must be empty and run at the nominal rpm.
• Measures for sealing the system (e.g. blocking air that enters from
above into the rotary valve) must be connected.
• The compressor must be switched on.
NOTE Scaling of the x-axis of the leakage characteristic is based upon this
pressure value. The upper limit is this value times a factor of 0.85.
Up to 21 reference points are determined.
Example: at an admission pressure of 2.0 bar, the characteristic curve
is obtained from 0 to 1.7 bar in 85 mbar steps
.