Brooks Instrument 4800 Series - Manual (Page 25)

4-3
Brooks ® 4800 Series
Section 4 Maintenance and Troubleshooting Installation and Operation Manual
X-TMF-4800-MFC-eng
Part Number: 541B072AAG
September, 2013
4-2-2 Frequently Asked Questions
Q: Where is the zero button?
A: There is no zero button on the 4800 Series devices.The re-zeroing
function is handled via a PC-based software tool. Refer to "Zeroing the
MFC (Self-Zero)" in Section 3-4 for instructions on how to obtain the
software.
Q: Doesn't the use of CO
2
necessitate the use of Buna O-rings?
A: Not in this case. A material compatibility analysis performed in
cooperation with the Advanced Design Center in Columbus, Ohio,
U.S.A., concluded that there are no significant issues with the use of
Viton
® fluoroelastomers with CO
2
under 10 bar (150 psig). Most other
Brooks mass flow controllers are capable of operating at much higher
pressures. This is why Brooks typically specifies Buna for CO
2
.
Q: Does the 4800 device have a low flow setpoint cut off?
A: Yes. The low flow setpoint cut off prevents the valve from opening
whenever there is a setpoint below 1% FS. During this time the valve
drive will be zero to achieve complete valve closure.
Q: Does the 4800 device have a low flow signal cutoff?
A: Yes. When the internal flow signal is less than 1% FS, the device will
report a flow output signal of zero.
4-2-3 System Checks
The Brooks 4800 Series Flowmeters and Controllers are generally used as
a component in gas handling systems, which can be complex in nature. It
can therefore be very difficult to isolate a malfunction in the system. An
inaccurately diagnosed malfunction can cause many hours of unnecessary
downtime. If possible, perform the following system checks before
removing a suspect Mass Flow Meter or Controller for bench
troubleshooting or return to the factory (especially if the system is new):
1. Verify a low resistance common connection and that the correct power
supply voltage and signals are present of the connector of the device.
2. Verify that the process gas connections have been made correctly, and
that they have been tested for leaks.