Endress+Hauser Levelflex FMP51 Modbus Technical Information page 28

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Notes on the mechanical load of the probe
Tensile load limit of rope probes
Sensor Feature 060
FMP51 LA, LB
MB, MD
Bending strength of rod probes
Sensor Feature 060
FMP51 AA, AB
AC, AD
AL, AM
BA, BB, BC, BD
Bending load (torque) through fluid flow
The formula for calculating the bending torque M impacting on the probe:
M = c ⋅ ρ/2 ⋅ v 2 ⋅ d ⋅ L ⋅ (L - 0.5 ⋅ L)
w N
with:
c : Friction factor
w
ρ [kg/m 3 ]: Density of the medium
v [m/s]: Velocity of the medium perpendicular to the probe rod
d [m]: Diameter of the probe rod
L [m]: Level
LN [m]: Probe length
Calculation example
Friction factor c 0,9 (on the assumption of a turbulent current - high
w
Reynolds number)
3
Density ρ [kg/m ] 1000 (e.g. water)
Probe diameter d [m] 0,008
L = L (worst case)
N
Probe
Rope 4mm (1/6") 316
Probe
Rod 8mm (1/3") 316L
Rod 12mm (1/2") 316L
Rod 12mm (1/2") AlloyC
Rod 16mm (0.63") 316L divisible
Levelflex FMP51 Modbus
Tensile load limit [kN]
5
Bending strength [Nm]
10
30
30
30
v
d
Endress+Hauser
L
N
L
A0014175