Sierra Instruction Manual ATEX Certified Units: 640S-EEX & 780S-EEX
Page 9 of 15
6. Maintenance
6.1.
External Maintenance
The Sierra flow meters can be externally maintained with a dry clean cloth.
6.2.
Sensor Maintenance
The sensor can be maintained by switches off the power, removing the probe from the process
and cleaning the probe with a solvent compatible with 316SS. After cleaning the probe clean
and dry the sensor with compressed air before you insert it back it the process. It is not
recommended to us any Ultrasonic Bath cleaning.
6.3.
Internal Maintenance
Please make sure that the internals of the unit always stay dry and clean. There are no User
maintainable components inside the electronic compartment
7. Earthing
The Sierra Instruments units must be connected to a good quality earth. The units are provided
with internal and external earthing terminals.
7.1.
External Earthing
The external earthing connection is located on the boss on the outside of the housing and
consist of an 316SS screw (10-
24” UNC-2B tread), seal spring washer and cable shoe/crimp lug
suited for maximum 3 mm OD Ground cable connection.
When using the external earth terminal the provided or similar cable shoe/crimp lug with a seal
spring washer must be used to ensure that the cable lug is secured against loosening and
twisting.
7.2.
Internal Earthing
The internal earthing connection is located in the terminal housing and consist of an 316SS
screw (10-
24” UNC-2B tread), seal spring washer and cable shoe/crimp lug suited for maximum
3 mm OD Ground cable connection.
When using the external earth terminal the provided or similar cable shoe/crimp lug with a seal
spring washer must be used to ensure that the cable lug is secured against loosening and
twisting.
8. Warning
The electronics for EEX unit contain special Ex dedicated electronics. No customer modifications
are available and are strictly forbidden. Any modification or adjustment to the electronics can be
performed at the factory only.