136 SensyMaster FMT430, FMT450 THERMAL MASS FLOWMETER | OI/FMT430/450-EN REV. B
… 11 Maintenance
Sensor
The flowmeter sensor is largely maintenance-free.
The following items should be checked annually:
• Ambient conditions (air circulation, humidity).
• Tightness of the process connections.
• Cable entries, cover gaskets and cover screws.
• Operational reliability of power supply, lightning
protection and grounding.
Cleaning
When cleaning the exterior of meters, make sure that the
cleaning agent used does not corrode the housing surface and
the seals.
To avoid static charge, a damp cloth must be used for cleaning.
Cleaning the sensor element
It can be necessary to clean the thermal measuring element
when measuring gases with damp contamination.
The cleaning interval depends on the degree of contamination of
the measuring element and must be individually defined.
Damage to the sensor due to improper cleaning!
• Do not clean the sensor element with hard objects
(screwdrivers, tweezers or wire brushes).
• Do not clean the sensor element in an ultrasonic bath.
• Do not clean or dry the measuring element with
1. Switch off the power supply.
2. Disconnect electrical connections.
3. Disassemble the sensor from the pipe component or hot tap
fitting, as described in Assembly of the pipe component on
page 32 and Installation / Disassembly in connection with
the hot tap fitting on page 44.
4. Carefully clean the measuring element with warm water or an
alcohol solution using a soft brush or cotton swab.
5. Allow the sensor to dry or carefully dry with warm air.
6. Check that the gasket between the sensor and pipe
component or welding adapter is clean and in good
condition; if necessary replace it with a new gasket (O-Ring
Ø 55 mm × 3 mm (2.16 in × 0.12 in).
7. Install the sensor in the pipe component or hot tap fitting, as
described in chapter Assembly of the pipe component on
page 32 and Installation / Disassembly in connection with
the hot tap fitting on page 44.
8. Perform electrical connection (see Electrical connections on
page 54).
9. Perform commissioning (see Commissioning on page 72).
Integrated hot tap fitting
Replace the O-ring gaskets
Danger of injury due to improper maintenance!
Danger of injury due to leaking measuring medium during
disassembly of the changing device with piping under
pressure.
• Before starting maintenance, depressurize the piping and
Risk of fire!
Risk of fire due to the use of non-permissible grease for
oxygen applications.
• Only use permissible fitting grease for oxygen
applications (e.g. Krytox GPL-226).
After approx. 100 sensor installation and disassembly
procedures, the O-ring gaskets on the changing device must be
replaced. If you are working with dusty, abrasive or aggressive
measuring media, it may be necessary to replace these more
frequently.
O-ring gaskets may only be replaced by the manufacturer's
service department or by qualified personnel employed by the
operator.
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