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Series 820 Instruction Manual Chapter 4 Maintenance & Repair
IM-82-C 4-5
Flow Path Cleaning Model 822-S/824-S
Laminar Flow Element
The laminar flow element (LFE) is a precision flow divider which
diverts a preset amount of flow through the sensor tube. The LFE is
made of precision machined 316 stainless steel. The particular LFE
used depends on the gas and flow range of the instrument. Should
the LFE require cleaning or inspection due to deposition, use the ap-
propriate cleaning procedure which is specific to flow body size.
Figure 4-4. Low Flow Transducer LFE Cleaning
Low Flow Transducers:
The LFE is accessed by unscrewing the main inlet fitting and re-
moving it from the flow body. The LFE is screwed into the inlet fit-
ting, which has been specially machined for this purpose. To access
the components:
1. Remove the transducer from the system.
1. The inlet filter screen is held in place in the inlet fitting by the
LFE. Disassemble by holding the fitting steady with a wrench
and unscrewing the LFE with a medium flat-tipped screwdriver.
2. Remove the LFE assembly taking care not to bend the inlet
screen. Inspect the sealing O-ring and replace if necessary. In-
spect the inlet screen and replace if corroded or damaged. Light
to medium particulate contamination can be cleaned by back
washing with a suitable solvent. Air dry thoroughly.
3. Inspect the LFE for damage and replace if necessary. Replacement
of the LFE or inlet screen requires transducer re-calibration.
4. Re-assemble components. When the transducer is installed in the
system, leak test the connection. Re-zero the transducer (see
Chapter 3).
Caution!
When using toxic or cor-
rosive gases, purge the
unit thoroughly with inert
dry gas before disconnect-
ing from the gas line.