Emerson Process Management MICRO MOTION T-SERIES - Manual (Page 17)

• If the purge gas is heavier than air (such as argon), locate the inlet lower than the
outlet, so that the purge gas will displace air from bottom to top.
• If the purge gas is lighter than air (such as nitrogen), locate the inlet higher than
the outlet, so that the purge gas will displace air from top to bottom.
5. Make sure that there is a tight seal between the inlet connection and sensor case, so
that air cannot be drawn by suction into the case or purge line during the purging
process.
6. Run purge gas through the sensor.
The purge time is the amount of time required for full exchange of atmosphere to
inert gas. The larger the line size, the greater amount of time is required to purge
the case. See
Table 5-1 . If purge lines are being used, increase the purge time to fill
the additional volume of the purge line.
Note
Keep the purge gas pressure below 30 psig (2 bar).
Purge time Table 5-1:
Sensor model Purge rate, in ft 3 /hr (l/h) Time, in minutes
T025 20 (566) 1
T050 20 (566) 1
T075 20 (566) 3
T100 20 (566) 5
T150 20 (566) 10
7. At the appropriate time, shut off the gas supply, then immediately seal the purge
outlet and inlet connections with the purge plugs.
Note
Avoid pressurizing the sensor case. If pressure inside the case elevates above atmospheric
pressure during operation, the flowmeter density calibration will be inaccurate.
8. Make sure that the purge fitting seals are tight so that air cannot be drawn by
suction into the sensor case.
Supplementary information
Installation Manual 13