LEFM 3xxCi User Manual
IB1406 Rev 12
Section 2
Page 19
August 2017
Inlet piping configuration No. 1: 10D
o
Measuring installations using the LEFM 340Ci with 10 diameters or more of straight pipe
upstream (without a flow conditioner) and 3 diameters downstream are suitable for accuracy
class 0.5 and accuracy class 1.0 in piping arrangements that cause only mild disturbances
excluding expanders where the upstream pipe is smaller than the meter diameter. Examples of
permitted pipe arrangements upstream of the 10 diameters are bends, tees and reducers,
including single bends and out-of-plane combinations.
Inlet piping configuration No. 2: 15D (with flow conditioner)
o
Measuring installations using the LEFM 340Ci with 15 diameters or more of straight pipe
upstream inclusive of a flow conditioner with its inlet located 10 diameters from the meter, and
with 3 diameters downstream are suitable for accuracy class 0.5 and accuracy class 1.0 in piping
arrangements that cause severe disturbances including combinations of out-of-plane bends in
combination with partial blockage of the pipe. An example of a severe disturbance would be a
50% open gate valve installed between out-of-plane bends.
For all above configurations, the internal diameter of the pipe sections must be the same as the inlet and
outlet diameter of the meter. The pipe sections shall be considered identical if their diameters differ by no
more than 3%. For unidirectional flow, the temperature sensor well should be installed downstream of the
meter. The distance from the downstream flange face to the temperature sensor well should be between 2
and 5 internal diameters. For bi-directional flow installations, temperature sensor well should be located at
between 3 and 5 diameters from the flange of the meter.
Uncalibrated Meters
Some customers may request to have a meter delivered without calibration. In these instances, it is
expected that the general performance requirements of AGA 9 and ISO17089 (Class 1) will apply as per
Table 2. below.
Table 2.3 Uncalibrated Meter Performance
Pipe Sizes
Flows between Q
t
and Q
max
Flows between Q
min
and Q
t
Maximum
(Permissible) Error
Max Peak-to-Peak
Error
Maximum
(Permissible) Error
Max Peak-to-Peak
Error
4 to 10 NPS
+/-1.0%
1.0%
+/-1.4%
1.4%
12 and larger
+/-0.7%
0.7%
+/-1.4%
1.4%
