Bronkhorst®
Instruction Manual mini CORI-FLOW™ M1x
9.17.050O
27
The following factors can affect the zero-stability error (in order of importance):
·
fluid temperature
·
ambient temperature
·
mounting orientation
·
(inlet) pressure
·
fluid density
·
fluid viscosity
·
vibrations from the environment
·
pressure fluctuations
The table below shows some typical worst case values for different mini CORI-FLOW models. In practice, zero stability will
turn out to be better.
Model
DN (mm)
Zero stability
error
Nominal flow
M12
0.25
< 0.02 g/h
100 g/h
M13
0.5
< 0.2 g/h
1 kg/h
M14
1.3
< 6 g/h
10 kg/h
M15
3.12
< 50 g/h
100 kg/h
Prerequisites
Zeroing an instrument requires that:
·
the ambient conditions (temperature, pressure) match those of the operating environment of the instrument
·
the instrument is filled homogeneously and pressurized with the operational media, according to the typical process
conditions
·
there is absolutely no flow through the instrument; preferably, this is achieved by closing a valve immediately after the
outlet of the instrument (control valve, shut-off valve)
Blocking the flow through the instrument is essential; zeroing an instrument while there is still a flow will lead to
measurement errors.
Methods
Adjusting the zero point of an instrument can be done by the following methods:
·
manually (by using the multifunctional switch)
·
digitally (via RS-232 or fieldbus)
·
with the autozero function of a Bronkhorst® readout and control unit (E-8000, BRIGHT)
Regardless of the preferred method, the procedure takes approximately 60 seconds to complete (longer if the output signal
is unstable).
3.10.1 Manual procedure
To start the autozero function with the multifunctional switch, follow these instructions:
1. Change the setpoint of the instrument to 0 (zero)
2. Press and hold the multifunctional switch. After 4 seconds, the red LED
l
starts glowing for 4 seconds, after which the
green LED
l
starts glowing
3. At that moment (which is after 8 to 12 seconds), release the switch
The green LED starts to blink fast, indicating that the autozero function is being performed. On (successful) completion, the
green LED starts to glow continuously, while the output signal is 0% (parameter
Measure
= 0).
