VEGA VEGADIF 65 Chemical seal CSB - Manual (Page 10)

10
3 Planning instructions for isolating systems
Chemical seal CSB • for VEGADIF 65
36133-EN-130417
– DRD DN 50 (65 mm), PN 25, 316L
0 1 2 3 4 5 6 7 8 9 10
–40
–20
0
20
40
60
80
Umgebungstemperatur
[°C
]
Kapillarlänge [m]
Gruppe F
erlaubter
Einsatzbereich
Fig. 7: Permissible ambient temperature range depending on the capillary
length for chemical seals of group F
3.3 Dynamic behaviour of the chemical seals
The viscosity of the filling oil, the capillary length as well as the inner
diameter influence the frictional resistance. The higher the frictional
resistance, the longer the step response time. The step response time
is also influenced by the control volume of the measuring cell. The
lower the control volume of the measuring cell, the lesser the step
response time.
The following diagram shows the typical step response times (T90) of
the different filling oils depending on the measuring cell and capil-
lary inner diameter. The values are specified in seconds per meter
capillary length and must be multiplied by the actual length of the
capillaries. The step response time of the transmitter must also be
taken into account.
1
2
3
4
5
6
7
DN50
(1 mm)
DN80
(2 mm)
500 mbar 3 bar
DN50
(1 mm)
DN80
(2 mm)
0
2
4
6
8
Fig. 8: Typical step response times (T90) in s/m for different filling oils depend-
ing on the measuring cell and capillary inner diameter. Ambient temperature =
20 °C
1 Silicone oil
2 High temperature oil
3 Med. white oil
4 Inert oil
5 Nominal width
6 Capillary inner diameter
7 Measuring cell
Step response time