Dwyer UXF3 - Manual (Page 18)

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3.2.1. Length of straight pipe
The length of upstream and downstream straight pipe of the ultrasonic detector should be long enough to ensure accurate
measurements.
(D is nominal diameter for a pipe)
Type Length of upstream straight pipe Length of downstream straight pipe
90° vending
L ≥10D
10D or more
L ≥5D
Tee
L ≥50D
10D or more
10D or more
L ≥10D
Extension pipe
L ≥30D
1.5D or more
D
0.5D or more
L ≥5D
Contraction pipe
L ≥10D
L ≥5D
Individual valves
L ≥30D
When adjusting flow rate by the valve on the
upstream side
L ≥10D
When adjusting flow rate by the valve on the
downstream side
Pump
L ≥50D
Check valve
P
Isolation valve
Note) Source: Japan Electric Measuring Instruments Manufacturers' Association (JEMIS-032)
Bulletin F-107-UXF3