Endress+Hauser Levelflex FMP53 - Page 39

Levelflex FMP53
Endress+Hauser 39
Notes on the mechanical load of the probe
Lateral loading capacity (flexural strength) of rod probes
FMP53
Rod 8mm (0.31") 316L
10 Nm
Rod 8mm (0.31") 316L separable
10 Nm
Lateral load (bending moment) from flow conditions
The formula for calculating the bending moment M acting on the probe:
M = c
w
× ρ/2 × v
2
× d × L × (L
N
- 0.5 × L)
With:
c
w
: coefficient of friction
ρ [kg/m
3
]: density of the medium
v [m/s]: flow velocity of the medium, perpendicular to the probe rod
d [m]: diameter of the probe rod
L [m]: level
LN [m]: probe length
Sample calculation
v
L
N
L
d
A0014175
Coefficient of friction c
w
0.9 (assuming turbulent flow - high Reynolds number)
Density ρ [kg/m
3
] 1000 (e.g. water)
Probe diameter d [m] 0.008
L = L
N
(unfavorable conditions)
Bendingtorque[M]onrodprobes,diameter8mm(1/3”)
Probelength[ ]inmetersL
N
v=0.5m/s
v=0.7m/s
v=1.0m/s
max.bending torque
0.4 0.8 1.2 1.6 2 2.4 2.8 3.2 3.6 4
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
20.0
Bending [Nm]
torque
A0014182-EN