6.
MAINTENANCE
6.1
Introduction
It is important that the Mass Flow Controller/Controller is used with clean, filtered
gases only. Liquids may not be metered. Since the RTD sensor consists, in part,
of a small capillary stainless steel tube, it is prone to occlusion due to impedi-
ments or gas crystallization. Other flow passages are also easily obstructed.
Therefore, great care must be exercised to avoid the introduction of any potential
flow impediment. To protect the instrument a 50 micron (FMA Series Max. Flow 10
L/min) or 60 micron (FMA Series Max. Flow 50 and 100 L/min) filter is built into the
inlet of the flow transducer. The filter screen and the flow paths may require occa-
sional cleaning as described below. There is no other recommended maintenance
required. It is good practice, however, to keep the meter away from vibration, hot
or corrosive environments and excessive RF or magnetic interference.
If periodic calibrations are required they should be performed by qualified per-
sonnel and calibrating instruments, as described in section (7). It is recommend-
ed that units are returned to OMEGA
®
for repair service and calibration.
CAUTION: TO PROTECT SERVICING PERSONNEL IT IS
MANDATORY THAT ANY INSTRUMENT BEING SERVICED IS
COMPLETELY PURGED AND NEUTRALIZED OF TOXIC,
BACTERIOLOGICALLY INFECTED, CORROSIVE OR
RADIOACTIVE CONTENTS.
6.2
Flow Path Cleaning
Inspect visually the flow paths at the inlet and outlet ends of the meter for any
debris that may be clogging the flow through the meter. Remove debris carefully
using tweezers and blowing low pressure clean air or Nitrogen from the inlet side.
If the flow path is not unclogged, please return to Omega
7
for servicing.
Do not attempt to disassemble the sensor. Disassembly will
invalidate calibration.
6.2.1
Cleaning the Inlet Filter Screen in FMA
5400A/5500A Series Max. Flow 10
Unscrew the inlet compression fitting of meter. Note that the Restrictor Flow
Element (RFE) is connected to the inlet fitting.
The Restrictor Flow Element (RFE) is a precision flow divider inside the trans-
ducer, which splits the inlet gas flow by a fixed ratio to the sensor and main flow
paths. The particular RFE used in a given Mass Flow Controller depends on the
gas and flow range of the instrument.
Carefully disassemble the RFE from the inlet connection. The 50 micron filter
screen will now become visible. Push the screen out through the inlet fitting. Clean
or replace each of the removed parts as necessary.
15
