BRONKHORST HIGH-TECH B.V.
page 14
9.17.044
3.3 Start-up
Turn on fluid supply gently. Avoid pressure shocks, and bring the instrument gradually up to the level of the
actual operating conditions. Also switch off fluid supply gently.
3.4 Operating
conditions
Each instrument has been calibrated and adjusted for customer process conditions.
Controllers or valves may not operate correctly, if process conditions vary too much, because of the
restriction of the orifice in the valve.
3.5 Instrument performance
3.5.1 Meters
Assuming that the transfer function of a system is an exponential shaped curve, the time constant is defined
as follows:
time constant = time for the signal to reach 63.2 % of its final output value. Approx. five time constants is the
time to reach the final value.
For the LIQUI-FLOW L30 meters the actual response depends on model and flow rate.
3.5.2 Controllers
The dynamic response of a controller is factory set. Standard settling-time is defined as the time to reach the
setpoint (and stay) within
±
2% of the initial setpoint. The settling time depends on the properties of the flow,
the system pressure and the valve type used.
The control mode is factory set in such a way that after a stepwise change in the flow, there will be little
overshoot.
3.6 Manual
operation
By means of manual operation of the push-button switch (#) some important actions for the instrument can
be selected/started. These options are available in both analog and BUS/digital operation modes.
(See also manual operation in document number 9.17.023)
These functions are:
- Reset (instrument firmware-program reset)
- Restore factory settings (in case of unintentionally change of the settings)
for FLOW-BUS only:
- Automatic installation to FLOW-BUS (installs instrument to free address)
- Remote installation to FLOW-BUS (instruments will be installed by E-7000 or PC-software)
