Recommended Steadying Run Lengths For Inlet Run Disturbances - ABB FMT400-VTS Operating Instruction

4.3

Recommended steadying run lengths for inlet run disturbances

Inlet and outlet runs must be provided to avoid negative effects on the measuring accuracy. These steadying run
lengths make sure that disturbances of the flow profile are eliminated before they can reach the actual measuring
point at the transducer. Straight, undisturbed pipe lengths are used as steadying run lengths, their length de-
pends on the type of the inlet run disturbance.
Recommended steadying lengths according to DIN EN ISO 5167-1
To achieve the stated measuring accuracy, the steadying lengths seen above must be provided.
The inlet and outlet run lengths are stated as multiples of the pipe diameter D.
For combinations of inlet run disturbances, e. g. valve and reducer, you must always consider the longer inlet
run length.
12 Thermal Mass Flowmeter FMT400-VTS, FMT400-VTCS (Sensyflow VT-S/VT-CS)
×
X D
< 7°
< 7°
Z-18941
Z-18943
Z-18944
Mounting and installation
×
5 D
Z-18938
Expansion
X = 15
Reducer
X = 15
90°-elbow
X = 20
Two 90°-elbows
in 1 level
X = 25
Two 90°-elbows
in 2 levels
X = 40
Valve/slide
X = 50
42/14-36 EN