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18 Inspection and maintenance
The equipment is subject to pressure!
▶ Risk of severe injury or death
Depressurize the plant.
●
Completely drain the plant.
●
Use of incorrect spare parts!
▶ Damage to the GEMÜ product
▶ Manufacturer liability and guarantee will be void
Use only genuine parts from GEMÜ.
●
Exceptional maintenance work!
▶ Damage to the GEMÜ product
Any maintenance work and repairs not described in these
●
operating instructions must not be performed without
consulting the manufacturer first.
The operator must carry out regular visual examinations of
the products, depending on the operating conditions and the
potentially hazardous situations, in order to prevent leakage
and damage.
1. Have servicing and maintenance work performed by
trained personnel.
2. Wear appropriate protective gear as specified in the plant
operator's guidelines.
3. Shut off plant or plant component.
4. Secure the plant or plant component against recommis-
sioning.
5. Depressurize the plant or plant component.
6. Actuate products which are always in the same position
four times a year.
18.1 Spare parts
No spare parts are available for this product. If it is faulty,
please return it to GEMÜ for repair.
18.2 Cleaning the product
- Clean the product with a damp cloth.
- Do not clean the product with a high pressure cleaning
device.
19 Disassembly
1. Disassemble in reverse order to assembly.
2. Unscrew the electrical wiring.
3. Deactivate the control medium.
4. Disconnect the control medium line(s).
5. Disassemble the product. Observe warning notes and
safety information.
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WARNING
CAUTION
NOTICE
20 General information regarding control engineering
20 General information regarding control engineer-
ing
20.1 The control circuit
Disturbance variable z
Volume flow fluctuations
20.2 Control engineering terminology
Reference variable (see Glossary)
Controlled variable (see Glossary)
Control difference (see Glossary)
Correcting variable y (see Glossary)
Disturbance variable z (see Glossary)
20.3 Control parameters
Explanation of product parameters:
Proc P: K
p
Proc I: T
n
Proc D: K
d
Proc T: T
v
Proportional band Xp (see Glossary)
Proportional action factor Kp (see Glossary)
Derivative action time Tv (see Glossary)
Differential component (D component) (see Glossary)
Integral-action component (I component) Ki (see Glossary)
Reset time Tn (see Glossary)
20.4 Adaptation of the controller to the controlled
system
Optimisation of the controller:
In order to achieve good behaviour of the control circuit, it is
necessary to adapt the positioner to the process. Good valve
behaviour, for instance, can be quick adjustment of maximum
power for pre-shooting or non-overshooting-free adjustment
of maximum power if the adjustment of power takes longer.
The optimum control parameters must be determined "manu-
ally" by trial and error through experimentation or rule of
thumb.
Explanation of product parameters:
Proc P: K
p
67 / 76
Reference variable w
Desired volume flow
GEMÜ 1436
positioner
Controlled
variable x:
Current volume
flow
Control valve
GEMÜ 3021 flowmeter
GEMÜ
GEMÜ 1436 cPos
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