6
3 Planning instructions for isolating systems
Chemical seal CSB • for VEGADIF 65
36133-EN-170317
3 Planning instructions for isolating
systems
3.1 Inuenceofthecomponents
The following properties of the separating diaphragm determine the
application area of the chemical seal:
• Diameter
• Resilience
• Material
The bigger the diaphragm diameter, the higher the resilience and the
smallerthetemperatureinuenceonthemeasuringresult.Note:To
keepthisinuencewithinreasonablelimits,youshoulduseachemi-
calsealwithanominalwidth≥DN80.
The resilience also depends on the diaphragm thickness, the material
as well as a possible coating.
ThecapillarylineinuencesthetemperaturecoecientTKZero point,
the permissible ambient temperature and the step response time of
an isolating system through its length and inner diameter. See also
chapter "Inuenceofthetemperatureonthezeropoint", "Ambient
temperature range" and "Step response time".
Intheselectionofllingoil,productandambienttemperatureas
well as process pressure are of utmost importance. Also take note of
temperatures and pressures during setup and cleaning.
Anothercriteriumisthecompatibilityofthellingoilwiththerequire-
ments of the medium. In the food processing industry, for example,
onlyllingoilsthatpresentnohealthrisksarepermitted,e.g.medici-
nalwhiteoil.Seeoverviewofllingoilsinthefollowingchart.
The table also shows the permissible medium temperature depending
on the isolating liquid and instrument version for pabs > 1 bar/14.5 psi.
For the medium temperature with instrument version for pabs
< 1 bar/14.5 psi, see chapter "Chemicalsealforvacuumapplica-
tions".
Filling oil Permissible medium
temperature with pabs
> 1 bar/14.5 psi
Density in
g/cm³ at
25 °C
Kinemat-
ic viscosity
in cSt at
25 °C
Corrective
factor for
TK
Application area
SiliconeoilKN17 -40…+180°C(-
40 … +356 °F)
0.96 4.4 1 Low temperatures
SiliconeoilKN2.2 -40…+200°C(-
40 … +392 °F)
0.96 54.5 1 Standard
High temperature oil
KN32
-10…+300°C(-
14 … +572 °F)
1.06 47.1 0.77 High temperatures
High temperature oil
KN32
-10 … +400 °C
(+14…+752°F)
1.06 47.1 0.77 High temperatures
HalocarbonoilKN21 -40…+150°C(-
40 … +302 °F)
1.89 10.6 0.83 For chlorine appli-
cations
Separating diaphragm
Capillaries
Chemicalsealllingoil