Endress+Hauser Prosonic M FMU42 HART Operating Instructions Manual page 10

Mounting
10
• Only mount one device per vessel: signals from multiple devices mutually affect one
another
• Determine the detection range using the 3-dB beam angle α
5.1.2 Beam angle
 5 Relationship between beam angle α, distance D and beamwidth diameter W
Beamwidth diameter W as a function of beam angle α and distance D.
• α: 9 °
• D : 10 m (33 ft)
max
• r : 0.79 m (2.6 ft)
max
The angle α is defined as the beam angle. At α, the energy density of the ultrasonic
wave reaches half the value of the maximum energy density. Ultrasonic waves are
also emitted outside the signal beam and can be reflected off interfering installations.
5.1.3 Narrow shafts, uneven shaft walls
 6 Installation in narrow shafts with very uneven shaft walls
1 Venting hole
Strong interference echoes can occur in narrow shafts and in uneven conditions.
‣
Use an ultrasound guide pipe with a minimum diameter of 100 mm (3.94 in), e.g. PE
or PVC wastewater pipe
Avoid the accumulation of dirt in the pipe.
‣
Clean the pipe regularly.
a
W = 2 · D · tan
2
a
W
1
Prosonic M FMU42 HART
A0038221
A0038233
Endress+Hauser