Panametrics Sentinel LCT, Руководство пользователя

Страница: 219 / 248

Sentinel LNG User’s Manual 207
Chapter 9. Troubleshooting
9.7 Uncertainty in Flow Rate for a Non-Insulated Meter
Dimensional compensation considers the effect on the geometrical dimensions of the meter due to the material
thermal expansion or contraction. The fluid temperature inside of the meter is measured and used for this purpose.
Under severe ambient conditions, eg. –40°C in winter, the fluid temperature can be very different, by up to 10°C, from
the actual wall temperature. This will cause about a 0.04% error in the flow rate measured. The Figure 229 below
indicates that the errors increase as the temperature difference between the fluid and the ambient for both insulated
and non-insulated meters. For non-insulated meters at large temperature differences, the error is about one order
higher than that for insulated meters. Therefore for applications in severe weather conditions, it is recommended to
insulate the meter to ensure the meter accuracy.
Figure 229: Example of Flow Error at Various Temperature Differences
-0.02
-0.01
0
0.01
0.02
0.03
0.04
0.05
-40 -20 0 20 40 60 80 100 120
Temperature Difference between Fluid and Ambinent (deg C)
E
rr
o
r in
F
lo
w
R
a
te
(%
)
SS306 with insulation
SS306 without insulation
Carbon Steel A106 with insulation
Carbon Steel A106 without insulation
Meter
Meter
meter
meter