Endress+Hauser NRF81 - Page 201

Tankside Monitor NRF81 Operating menu
Endress+Hauser 201
HTG evaluation: dependence on measured level
To calculate the level or density by HTG with the required accuracy, P1 and P2 have to be
covered by a certain product level. To avoid a measurement with an insufficient accuracy,
the calculation will stop before the level reaches the position of the pressure sensor.
Two parameters are defined for this purpose:
• Minimum level
This parameter defines the position below which no level is accepted. If the calculation
leads to Tank level < Minimum level, the value of Minimum level will be displayed
instead of the calculated value.
• Safety distance
This parameter defines the minimum amount of product which must be present above
the pressure sensor P1 or P2 for the level or density calculation to take place.
• The device always uses the bigger of these two values as the switch-over point for
the level calculation.
• If HTG mode (→  206) is set to P1 only or P1 + P3, the density is not calculated
and the Manual upper density parameter is used instead.
Case 1: H
P1
< Minimum level < H
P2
A
B
C
3
P3
P2
P1
1
2
5
4
A0028718
1 P1 position (→  182)
2 Safety distance (→  208)
3 P1-2 distance (→  184)
4 Safety distance (→  208)
5 Minimum level (→  207)
Level L is in area Calculation method for ρ
P
Calculation method for L
A calculated from pressure calculated from pressure
B ρ
P
held calculated from pressure
C ρ
P
held L = Minimum level