Honeywell Enraf VITO, Instruction Manual

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Average temperature measurement with VITO temperature probes
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Instruction manual VITO Page 9
Average product temperature is calculated from all submerged elements from the reference element and higher
located elements. Before an element is used in the average product temperature calculation, it must be
submerged by a certain amount of product, specified by item
MP
(product immersion depth; default 0.5 m (20”)).
According to the international recommendations (API and ISO) for temperature measurement in storage tanks,
the lowest element shall be located 1 m (3 ft) from the bottom of the tank. The VITO probe models 764
C , 766 C ,
767 C and 768 C fulfil this recommendation.
The VITO probe models 764
D , 766 D , 767 D and 768 D also fulfil this recommendation, but have in addition one
element at the bottom of the probe. By default, the lowest element at the bottom of the probe is not used for
average product temperature calculations. Only when the level is such low that the reference element is not
selected anymore for average product temperature calculation, the lowest element is used as average product
temperature but with a special temperature status (level below lowest element). That will be shown on the tank
gauging system as a temperature with reduced accuracy.
By means of a ‘switch’ (item
MJ ) one can also enable the lowest element close to the bottom of the probe for
average product temperature calculation.
For the combi probes (water & temperature probes models 766
D
and 768
D
) an additional condition is that the
lowest element is only used when no water is detected.
Note:
When the lowest element close to the bottom of the probe is enabled for average temperature calculation,
the temperature measurement system is not operating according the international recommendations.
2.2
Commissioning of VITO temperature probe
The commissioning of the optional average temperature part should be performed after the basic commissioning
of the level gauge or indicator.