System Description; General Description; Lfc, Liquid Flow Controller; Lfm, Liquid Flow Meter - Burkert 8718 Manuel D'utilisation

Type 8718, 8719 / 8708, 8709

System Description

5. sysTeM descripTiOn
5.1. general description
The LFC / LFM Types 8718, 8719 / 8708, 8709 are devices for controlling or measuring the flow-rate of liquids
in process technology.
The devices are specified for the control and measurement of low flow-rates.
5.1.1. lfc, liquid flow controller
The actual flow-rate value supplied by the integrated sensor is compared in the digital control electronics with the
set-point flow-rate value specified, via a standard signal or field bus. The actual flow-rate value is also available as
an output, via a standard signal or field bus.
If there is a control deviation, the actuating variable output to the proportional valve is modified via a control
algorithm. As a result, the actual flow-rate is adjusted to the set-point value and the flow-rate can be held on a
fixed value or follow a predefined profile sequence, irrespective of pressure changes or other disturbances in the
system.
A low-friction proportional valve with a high response sensitivity is used as an actuating element.
5.1.2. lfM, liquid flow Meter
The actual flow-rate value supplied by the integrated sensor is available as an output, via a standard signal or field
bus.
5.2.

functions

5.2.1. function of the lfc, liquid flow controller
The LFC Types 8718 and 8719 are compact devices for controlling the flow-rate of liquids.
They correct a stipulated set-point flow-rate value independently of disturbance variables, such as pressure fluc-
tuations or fluctuating flow resistance, e.g. due to filter soiling.
The Liquid Flow Controller consists of the following components:
• Flow sensor (Q sensor),
• Control electronics (with signal processing, control and valve actuation functions),
• Proportional solenoid valve as an actuating element.
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