KROHNE BM 70 M - Manual (Page 15)

BM 70 M 15
D
>1/7×H, but max. 1/3×D
Antenna Type 3
or Wave-Stick
H
measurable
level
min.
Safety:
• Operator control via the keys: on electrical safety grounds, operator control of the keys (below
the display, with the housing open) may only be carried out by specialist personnel for service
and repair work, on no account, however, when there is risk of explosion!
•
Surface temperature: the housing of the signal converter can, in extreme ambient conditions,
assume temperatures of more than 70°C (158°F)!
6.1 Installation conditions
6.1.1 Transmission angle
The transmission angle is defined as the angle . to the vertical, in which the power density of the
radar waves assumes half the value of the maximum power density (half-power beam width):
Antenna
Type Diameter
mm
(inches) Transmissi
on angle
α
Lobe expansion s
per metre distance
Type 4 200 (7.87) 6° 10 cm (3.94”)
Type 3s* 140 (5.51) 8° 14 cm (5.51”)
Type 2s* 100 (3.94) 12° * 22 cm (8.67”)
Type 1s* 80 (3.15) 16° * 30 cm (11.8”)
Wave-Guide
/ stilling well 25-200
(0.98-7.87) Propagation only inside the stilling
well
* Should only be used in stilling wells; the transmission angle given
applies to line-of-sight propagation, i.e. without stilling well.
6.1.2 Recommendations for positioning on the tank
A) Horn antenna or Wave-Stick without stilling well
Recommended distance from
the tank wall Lower measuring range
limited when tank has tapered
bottom. Several BM 70 M can be
operated in one tank.
α α
s