Siemens SITRANS P DS III - Page 52

Installing / mounting
4.4 "Level" installation
SITRANS P DS III with PROFIBUS PA
52 Operating Instructions, 06/2013, A5E00053276-07
When taking measurements in a closed container with strong condensate formation, you
must fill the negative pressure line (mostly with the condensate of the measured medium)
and install a condensate pot. You can cut off the device using the dual pneumatic block
7MF9001-2.
Measurement assembly on a closed container (strong
condensate formation)
Formula:
Start
-of-scale value:
Δp
MA
= g · (h
U
· ρ- h
V
· ρ')
Full
-scale value:
Δp
MA
= g · (h
O
· ρ- h
V
· ρ')
h
U
Lower filling level
Δp
MA
Start of scale value
h
O
Upper filling level
Δp
ME
Full-scale value
h
V
Gland distance
ρ
Density of the measured med
ium in
the container
p
Pressure
ρ '
Density of fluid in the negative
pressure line corresponds to the
prevailing temperature there
g
Acceleration due to gravity
The process connection on the negative side is a female thread
1
/
4
-18 NPT or an oval flange.
Lay the line for the negative pressure using a seamless steel tube 12 mm x 1.5 mm.