Bronkhorst®
Instruction Manual EL-FLOW® Prestige
9.17.084N
15
3
Basic operation
3.1
Mass flow measurement and control
After correct installation of the
EL-FLOW® Prestige
Mass Flow Meter (MFM) or Mass Flow Controller (MFC) and when all
safety precautions have been taken into account the instrument can immediately be used for measuring/ controlling the
required flow rate in the system by means of the selected communication interface(s).
Here are some general guidelines for mass flow measurement/control:
EL-FLOW® Prestige
MFMs/MFCs are most accurate at the specified inlet/outlet pressure, temperature and process gas
conditions, however the instrument will function properly in a wide range of varying conditions. It is strongly advised to use
the FlowTune™ software available with the instrument to set the correct process conditions if the actual process conditions
differ from the conditions for which the instrument is set (see further).
Although
EL-FLOW® Prestige
MFMs/MFCs have excellent temperature stability, the best accuracy is achieved when
temperature differences across the instruments are avoided; make sure that the gas temperature equals the ambient
temperature and mount the instruments on a rigid (heat conducting) surface.
Regular
EL-FLOW® Prestige
MFCs handle pressure shocks in the system well, but are not insensitive to pressure
fluctuations. For optimum control stability, provide a stable (pressure controlled) inlet pressure with sufficient buffer
volume between the pressure regulator and the MFC and avoid installing multiple MFCs or other control valves in close
proximity to another with small volume piping in between.
EL-FLOW® Prestige PI
instruments (see
) and instruments with
I/O option H1P
enabled (see
Customized I/O options (pin 5)
) automatically and continuously adjust the flow rate, based on the actual pressure
measured by the built-in or external pressure sensor respectively.
When an MFC (either with normally closed (NC) or normally
open (NO) valve) is hooked-up, the control valve stays closed
when no setpoint is given. When the MFC receives a setpoint
from the active setpoint source, the internal PID controller will
immediately open the control valve until the required flow
rate is achieved and it will maintain that flow rate until
another setpoint is given.
3.1.1
Changing fluid set, range or operating conditions
EL-FLOW® Prestige
instruments provide Multi Fluid/Multi Range functionality (MFMR). With this functionality, the properties
of a selection of 100 pre-installed gases or any mixture thereof can be used to reconfigure the instrument.
