Endress+Hauser Levelflex FMP51 Operating Instructions Manual page 36

Mounting
36
Bending strength of rod probes
Sensor Feature 060
FMP51 AA, AB
AC, AD
AL, AM
BA, BB, BC, BD
FMP52 CA, CB
FMP54 AE, AF
BA, BB, BC, BD
Bending load (torque) through fluid flow
The formula for calculating the bending torque M impacting on the probe:
× r/2 × v × d × L × (L
M = c 2
w
with:
c : Friction factor
w
r [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 Reynolds
w
number)
Density r [kg/m
3 ] 1000 (e.g. water)
Probe diameter d [m] 0,008
L = L (worst case)
N
Bending torque [M] on rod probes, diameter 8mm (1/3")
20.0
18.0
16.0
14.0
12.0
10.0
8.0
6.0
4.0
2.0
0.0
0.4 0.8 1.2
Probe
Rod 8mm (1/3") 316L
Rod 12mm (1/2") 316L
Rod 12mm (1/2") AlloyC
Rod 16mm (0.63") 316L divisible
Rod 16mm (0.63") PFA>316L
Rod 16mm (0.63") 316L
Rod 16mm (0.63") 316L divisible
- 0.5 × L)
N
1.6 2 2.4 2.8 3.2
Probe length [ ] in meters L
N
Levelflex FMP51, FMP52, FMP54
Bending strength [Nm]
10
30
30
30
30
30
30
v
d
v=0.5m/s
v=0.7m/s
3.6 4
v=1.0m/s
Endress+Hauser
L
N
L
A0014175
A0014182-EN