Operating menu
Micropilot NMR84
200
Hauser
HTMS modes
Two HTMS modes can be selected in the
HTMS mode
determines whether one or two pressure values are used. Depending on the selected mode
a number of additional parameters are required for the calculation of the product density.
The
HTMS P1+P3
option must be used in pressurized tanks in order to compensate
for the pressure of the vapor phase.
HTMS mode
(→ 201)
Measured variables Required additional parameters Calculated variables
HTMS P1
• P
1
• L
P
• g
• H
P1
• L
W
(optional)
ρ
P
HTMS P1+P3
• P
1
• P
3
• L
P
• ρ
V
• ρ
A
• g
• H
P1
• H
P3
• L
W
(optional)
ρ
P
(more precise calculation
for pressurized tanks)
Minimum level
The density of the product can only be calculated if the product has a minimum thickness :
Δ
Δ
P
P, min
≥
A0028864
This is equivalent to the following condition for the product level:
L
V
H
L
P
P
P
-
³
+
=
D
,min
min
1
A0028863
L
min
is defined in the
Minimum level
parameter (→ 202). As can be seen from the
formula it always must be bigger than H
P1
.
If L
P
- V falls below this limit, the density is calculated as follows:
• If a previous calculated value is available, this value will be kept as long as no new
calculation is possible.
• If no value was previously calculated, the manual value (defined in the
Manual upper
density
parameter) will be used.
Hysteresis
The level of the product in a tank is not constant but slightly varies, due for example to
filling disturbances. If the level oscillates around the changeover level (
Minimum level
), the algorithm will constantly switch between calculating the value and
holding the previous result. To avoid this effect a positional hysteresis is defined around
the changeover point.
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