6 Supplementary information
6.1 Purge the sensor case
Prerequisites
Make sure the following are available before beginning the purge procedure:
• Teflon
™
tape
• Argon or nitrogen gas sufficient to purge the sensor case
Whenever a purge plug is removed from the sensor case, you must purge the case again.
Procedure
1. Shut down the process, or set control devices for manual operation.
NOTICE
Before performing the case purging procedure, shut down the process or set the
control devices for manual operation. Performing the purge procedure while the
flowmeter is operating could affect measurement accuracy, resulting in inaccurate
flow signals.
2. Remove both purge plugs from the sensor case. If purge lines are being used, open
the valve in the purge lines.
WARNING
• If a rupture disk has been installed on the purge fitting, stay clear of the
rupture disk pressure relief area. High-pressure fluid escaping from the sensor
can cause severe injury or death. Orient the sensor so that personnel and
equipment will not be exposed to any discharge along the pressure relief path.
• Take all necessary precautions when removing purge plugs. Removing a purge
plug compromises the secondary containment of the sensor and could expose
the user to process fluid.
• Improper pressurization of the sensor case could result in injury.
NOTICE
If a rupture disk has been installed on the purge fitting, use thread protectors when
removing the purge fitting so as not to damage the disk membrane surrounding
the rupture disk.
3. Prepare the purge plugs for reinstallation by wrapping them with 2–3 turns of
Teflon tape.
4. Connect the supply of nitrogen or argon gas to the inlet purge connection or open
inlet purge line. Leave the outlet connection open.
NOTICE
• Exercise caution to avoid introducing dirt, moisture, rust, or other contaminants
into the sensor case.
Installation Manual Supplementary information
20002298 April 2020
Installation Manual 21
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