Influence Of Temperature Changes - Vega VEGADIF 65 Operating Instructions Manual

Filling oil
Halocarbon oil KN21
(BAM tested)
Med. white oil KN92
(FDA approved)
Neobee M-20 KN59
(FDA approved)
Differential pressure
transmitter
Influence of the tempera-
ture on the zero point
Chemical seal CSB • for VEGADIF 65
Permissible medium
temperature with p
abs
> 1 bar/14.5 psi
-40 ... +60 °C (-
40 ... +140 °F)
-10 ... +250 °C
(+14 ... +482 °F)
-10 ... +150 °C
(+14 ... +302 °F)
The implemented filling oil also influences the TK
sible ambient temperature and the step response time of a chemical
seal. See also chapter "Influence of the temperature on the zero
point" and "Step response time".
The differential pressure transmitter also influences the temperature
application range, the TK
lating system through the volume of its lateral flanges and its control
volume.
1)
3.2 Influence of temperature changes
The filling oil expands as the temperature increases. The additional
volume presses on the chemical seal. The more rigid the diaphragm,
the more it counteracts a volume change. The additional volume also
adds to the process pressure on the measuring cell and thus shifts
the zero point. The respective temperature coefficient "TK
listed in chapter "Dimensions and weights".
The following diagram shows the temperature coefficient depending
on the capillary length. The process temperature corresponds to the
calibration temperature. The temperature coefficients determined
from the diagram apply to silicone oil and the diaphragm material
316L. For other filling oil, these temperature coefficients have to be
multiplied with the correction factor for the TK of the respective filling
oil.
The control volume is the volume that must be shifted in order to utilise the
1)
entire measuring range.
3 Planning instructions for isolating systems
Density in Kinemat-
g/cm³ at ic viscosity
25 °C in cSt at
25 °C
1.89 10.6
0.85 45.3
0.92 10
and the step response time of the iso-
zero point
Corrective Application area
factor for
TK
0.83 For oxygen appli-
cations
0.63 Food applications
Food applications
, the permis-
zero point
Process
" is
7