Siemens SITRANS P - Manual (Page 186)

SITRANS P measuring instruments for pressure
Remote seals
Measuring setups without remote seals
2/186 Siemens FI 01 · 2009
2
Measuring setups for closed containers
r
Ho
Hu
Level measurement, Version 1
Start-of-scale: Dp
MA
= r · g · H
U
Full-scale: Dp
ME
= r · g · H
O
Legend
Dp
MA
Start-of-scale value to be set
Dp
ME
Full-scale value to be set
r Density of medium in vessel
g Local acceleration due to gravity
H
U
Start-of-scale value
H
O
Full-scale value
Maximum level
Start-of-scale value
Full-scale value
Transmitter
reference line
Static
pressure Gas-filled negative
pressure line
Maximum level
H
r
r
r' Hv
Hu
2
2
1
o
Separation layer measurement
Start-of-scale: Dp
MA
= g · (H
U
· r
1
+ (H
O
- H
U
) · r
2
- H
V
· r'
2
)
Full-scale: Dp
ME
= g · (H
O
· r
1
- H
V
· r'
2
)
Legend
Dp
MA
Start-of-scale value to be set
Dp
ME
Full-scale value to be set
r
1
Density of heavier liquid with separation layer
in vessel
r
2
Density of lighter liquid with separation layer
r'
2
Density of liquid in the negative pressure line
(corresponding to the temperature existing there)
g Local acceleration due to gravity
H
U
Start-of-scale value
H
O
Full-scale value
H
V
Distance between the measuring points
(spigots)
Max. separation layer
Start-of-scale value
Full-scale value
Static
pressure
Constant level
Static
pressure
Transmitter
reference line
© Siemens AG 2008