Dwyer GFC - Manual (Page 18)

Note: Over tightening will deform and render the RFE defective.
It is advisable that at least one calibration point be checked after re installing the
inlet fitting - see section (7).
6.2.2 Cleaning the inlet Filter screen in GFC-113/114 Models
Unscrew the four socket head cap screws (two 10-24 and two 6-32) at the inlet
side of the meter. This will release the short square block containing the inlet
compression fitting.
The 60 micron filter screen will now become visible. Remove the screen DO NOT
remove the RFE inside the flow transducer! Clean or replace each of the removed
parts as necessary. If alcohol is used for cleaning, allow time for drying.
Inspect the flow path inside the transducer for any visible signs of contaminants.
If necessary, flush the flow path through with alcohol. Thoroughly dry the flow
paths by flowing clean dry gas through.
Re-install the inlet parts and filter screen. Be sure that no dust has collected on
the O-ring seal.
It is not recommended to attempt to disassemble, or repair GFC-113,
GFC-114, GFC-1143, GFC-1144 and GFC-1145 models.
Disassembly necessitates re-calibration.
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6.2.1 Cleaning the Inlet Filter Screen in GFC-110/111 Models
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 preset amount 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. If alcohol is used for clean-
ing, allow time for drying before re-assembling.
Inspect the flow path inside the transducer for any visible signs of contaminants.
If necessary, flush the flow path through with alcohol. Thoroughly dry the flow
paths by flowing clean dry gas through.
Carefully re-install the RFE and inlet fitting, avoiding any twisting and deforming
the RFE. Be sure that no dust has collected on the O-ring seal.
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