Brooks Instrument 4800 Series - Manual (Page 21)

3-3
Brooks ® 4800 Series
Section 3 Operation Installation and Operation Manual
X-TMF-4800-MFC-eng
Part Number: 541B072AAG
September, 2013
Setpoint
Signal Type
Full Scale Zero Signal
0 to 5 Vdc 5 Vdc 0 V
4 to 20 mA 20 mA 4 mA
Flow Signal Output
This output is used to indicate the flow signal.
Several flow signal types are available:
Flow Signal
Type Full Scale Zero Signal Maximum Signal
0 to 5 Vdc 5 Vdc 0 V 5.5 Vdc = 110%
4 to 20 mA 20 mA 4 mA 21.6 mA = 110%
Valve Override (MFC Only)
Connector Pin 12 on the 15-pin D-Connector allows the valve to be forced
to its most closed state or its most open state, regardless of setpoint. If this
input is not electrically connected, the MFC will operate according to the
current values of the other MFC inputs. If this input is held at 0 Vdc
(<0.3 V), the valve will be forced to its most closed state. If this input is held
at +5 Vdc (>4.8 V), the valve will be forced to its open state.
The valve override function can also be accessed via RS232. An optional
software tool for ease of RS232 connection is available on the Brooks
Instrument website. See Section 3, PC-based Support Tools for
instructions on how to access this software.
Zeroing the MFC (Self-Zero)
It may be desirable to re-zero the flow sensor if it is operated at its
temperature extremes or if it is positioned in an attitude other than that
specified on the customer order.
Note: Before zeroing the instrument, zero pressure differential MUST
be established across the device. If there is pressure across the
instrument during the zero process, any detected flow through the
sensor will be misinterpreted as the zero flow reading. This will result
in calibration inaccuracy during normal operation.
The re-zero function can be accessed via RS232. An optional software tool
for ease of RS232 connection is available on the Brooks Instrument
website. See Section 3, PC-based Support Tools for instructions on how to
access this software.