KROHNE BM 70 M - Manual (Page 23)

BM 70 M 23
6.3.2 Relative permittivity (
ε
r
≥
1.5)
The (relative) permittivity of the product (
ε
r
, Epsilon-R) determines the strength of the reflected
signal. Measurement results are not affected so long as the reflected signal is strong enough, but
reliability and the maximum measuring range are dependent upon the relative permittivity.
At ε
r
< 3, a stilling well should be used. The minimum relative permittivity of the product is
approximately ε
r
= 1.5. (See also Section 7.5).
If the Wave-Stick is also to take measurements when immersed, ε
r
will need to be > 4.
6.3.3 Product limitations
Radar-based level measuring devices are not suitable for the following products:
•
liquid ammonia
• liquid hydrogen
• liquid helium
6.3.4 Product temperature (unrestricted)
The product temperature is not a relevant factor, provided the ambient temperature (see 6.2.2)
and the flange temperature (see 6.2.3) are within the specified limits.
6.3.5 Maximum allowable operating pressure
Flange system with horn antenna or Wave-Guide:
PN 16 PN 25 PN 40
DN 80 16 bar (232 psig) --- 40 bar (580 psig)
DN 100 16 bar (232 psig) --- 38 bar (551 psig)
DN 150 16 bar (232 psig) --- 34 bar (493 psig)
DN 200 16 bar (232 psig) 25 bar (363 psig) 32 bar (464 psig)
Information on higher pressures supplied on request.
0%
10%
20%
30%
40%
50%
60%
70%
1 1.2 1.6 2 2.5 3.2 4 5 6.3 8 10 12 16 20 25 40 50 63 80 32
Dielectric Constant and Reflection Factor
R
ε
r Water
Benzene
Toluene
Petrol
Chlorine
Phosgene
Methanol
LPG Sulfuric acid
Sulfur
Phenol
Nitrobenzene
Glycol
Paraffin
U S E A B L E R A N G E