Water bottom measurement
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Instruction manual VITO
Page 37
Figure 5.2 Calibration measurements for water probe
If the commissioning takes place directly after installation, the measurements at the probe position in figure 5.2
have already been made if the instructions are followed from the installation guide. Otherwise, that measurement
should be made now, by partly removing the probe to enable a measuring tape to be lowered from the nozzle.
The following values are obtained:
•
Nozzle height
•
Product level at water probe location
•
Water level at water probe location
From these measurements, calculate the ‘ullage’ value ‘A’:
A
= nozzle height – product level at water probe location
The next step is to fetch the product level with respect to the tank zero point. This can be done in several ways:
•
Read the level from the level gauge if that has recently been checked (calibrated);
•
Take a manual ‘innage’ measurement to the datum plate of the tank;
•
Take a manual ‘ullage’ measurement from the Upper Reference Point and calculate the level by: level =
URP – ‘ullage’.
Refer to figure 5.2. At the bottom part of the probe there is an inactive metal part with a height of 25mm (1”).
That is represented as distance
‘B’
.
The offset, which had to be programmed in item
WB
, can be found from:
WB
= (
A
+ product level at reference point) – (Nozzle height –
B
)
For example:
Nozzle height =
18.375 m (or 723.43 inch or 60.285 ft)
Product level at water probe location = 13.832 m (or 544.57 inch or 45.381 ft)
Then ‘
A
’ becomes:
4.543 m (or 178.86 inch or 14.904 ft)
The product level (innage dip) =
13.823 m (or 544.21 inch or 45.351 ft)
The inactive metal part at bottom probe= 0.025 m (or 0.98 inch or 0.082 ft)
Содержание Enraf VITO
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