AFLOWT LV Series, Installation Manual

Page: 10 / 38

10
5. START-UP PROCEDURES
5.1. Initial configuration
5.1.1. Prior to work, it is necessary to check that the Level gauge's operation
settings specified in the Equipment Certificate or Check Form
correspond to the ones in the Device's internal memory as well as to
check its configuration settings.
The following settings shown in Fig.1 are determined during the
configuration procedure, after which they are entered in the Device's
Start-up List (Appendix D):
- B
– base level, m
- H
max
– maximal level of liquid in the tank under control
- C0
– velocity of ultrasound in gas medium inside the tank under control
at 0°C (applicable only for systems AS-11x-xx3, AS-61x-xx0, AS-62x-
xx0, AS-71x-xx0, AS-72x-xx0)
, m/s
- Volume/Level characteristic of the tank under control (required for
calculation of volume and/or filled volume).
When configuring the Device, the following settings are also
checked and recalculated:
- D
min
, D
max
– threshold values of the distance measuring range, m
- C
min
, C
max
– threshold values of the range of actual ultrasound velocities
within the sound guide , m/s;
- C
mc
– ultrasound velocity value entered for the manual correction mode
(if necessary), m/s.
5.1.2. In the course of start-up, the base level B can be determined by two
methods:
- Measuring the distance between the base (reference) plane, from which
the distance readings are taken, and the bottom of the tank or a
conventional plane which is taken as the reference for level
measurements
- Calculating the sum of measured distance D
mcr
and liquid level H
mcr
in
the tank under control:
B = D
mcr
+ H
mcr
(1)
The distance is determined as a range from the base plane to the
media interface. You may use the Level gauge readings to determine
the distance.
For all acoustic systems, the base plane is a plane going through
the outer surface of the mount flange, mount bar, or mount disc.
Values of distance, level and the measurement base can be
measured by a measuring crossbar, measuring needle, or laser ranger.
The recommended accuracy for distance, level, and base level
measurements is ± 1 mm.
5.1.3. The threshold values for distance measuring range D
min
and D
max
are
calculated as follows:
D
min
= B
– 1.2
⋅
H
max
(2)