Siemens SITRANS FC410 Operating Instructions Manual page 37

The selection of pressure guard solution is the responsibility of the user, however Siemens
recommends the following forms of pressure guard:
● A pressure switch screwed directly or piped into one of the purge ports and connected to
an automatic shut-off valve will disable pressurized supply to the meter.
● A relief valve or bursting disc screwed directly or piped to one of the purge ports to carry
any spilt fluid to drain after opening.
The pressure switch and relief valve set point should be 2-3 bar gauge. The pressure switch
should be rated to withstand the full process pressure and temperature for a short time
without rupture.
Drain flow
Ensure the drain flow is safely contained away from personnel and other plant or
equipment.
Mounting of pressure guard
Moisture, liquids or particles getting into the sensor enclosure
All sensors are filled with argon to avoid condensation. Ingress of moisture, liquids or
particles into the sensor may influence the measurement and in worst case inhibit the
measuring function.
• Avoid moisture, liquids or particles getting into the sensor enclosure
Install a pressure guard as follows:
1. Place the sensor in a dry, clean place and leave it to acclimatize until it reaches ambient
temperature, preferred 20°C (68°F) with low humidity (at least below 50% RH).
2. Orient the sensor with the purge ports uppermost to minimize loss of the argon gas filling.
3. Carefully remove the plug and mount the pressure guard.
Use replacement soft metal sealing rings for proper sealing.
FC410 with Modbus
Operating Instructions, 02/2016, A5E33120874-AC
CAUTION
CAUTION
CAUTION
Lack of proper sealing
Soft metal sealing rings only maintain a hermetic seal within the enclosure with single
use.
• Ensure that soft metal sealing rings are not reused.
Installing/Mounting
4.1 Flowmeter installation
35