Installation
Deltabar S FMD77, FMD78, PMD75 with FOUNDATION Fieldbus
22
Hauser
Vacuum application (FMD78)
For applications under vacuum, Hauser recommends mounting the pressure
transmitter below the diaphragm seal. This prevents vacuum loading of the diaphragm seal
caused by the presence of fill fluid in the capillary.
When the pressure transmitter is mounted above the diaphragm seal, the maximum height
difference H1 in accordance with the illustrations below must not be exceeded.
A0023983
Fig. 20:
Installation above the lower diaphragm seal
The maximum height difference depends on the density of the filling oil and the smallest
ever pressure that is permitted to occur at the diaphragm seal (empty vessel), see illustration
below:
A0023986-en
Fig. 21:
Diagram of maximum installation height above the lower diaphragm seal for vacuum applications depending on the
pressure at the diaphragm seal on the positive side
A
Height difference H1
B
Pressure at diaphragm seal
1
Low temperature oil
2
Vegetable oil
3
Silicone oil
4
High-temperature oil
5
Inert oil
+
–
H1
1
2
3
4
5
A
B
0.0
2.0
4.0
6
.0
8.0
10.0
12.0
5
0 100
300
400
5
00
6
00
7
00
800
900 1000
200
[mbar ]
abs
[m]
Содержание Deltabar S FMD77
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