Siemens 7MF0400 - Page 32

To compensate the liquid column on the minus side, reset the zero point.
'
-
K
2
K
8
)XOOVFDOHYDOXH
6WDUWRIVFDOHYDOXH
0D[LPXPOHYHO
&RQVWDQW
&RPSDULVRQ
OHYHO
*DVILOOHG
QHJDWLYHSUHVVXUHOLQH
K
Y
3UHVVXUHWUDQVPLWWHU
UHIHUHQFHOLQH
Measurement assembly on a closed container (strong condensate
formation)
Formula:
Lower range value:
Δp
MA
= g · (h
U
· ρ - h
V
· ρ')
Upper range value:
Δp
MA
= g · (h
O
· ρ - h
V
· ρ')
h
U
Lower filling level Δp
MA
Lower range value
h
O
Upper filling level Δp
ME
Upper range value
h
V
Gland distance ρ Density of the measured medium in the
container
p Pressure ρ ' Density of fluid in the negative pressure
line corresponds to the prevailing tem‐
perature 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.
Installing/mounting
4.3 Installation (level)
SITRANS P320/P420 with 4 to 20 mA/HART
32 Compact Operating Instructions, 09/2018, A5E38874562-AB