Closed Tank Level Measurement; Vapor Flow - ABB Platinum standard Series Product Instruction

N OT E S :
1 . M O U N T T R A N S M IT TE R B E L OW P R IM A RY E L E M E N T C O N N E C T IO N S.
2 . A LL H O R IZ O N TA L LIN E S SH O U LD S L O P E AT L E A S T 8 3 M M /M (1 IN ./FT )
D O W N W A R D TO TR A N S M IT T E R .
3 . T R A N S M ITT E R S H O U L D B E T H O R O U G H LY V E N TE D TO AVO ID M E AS U R EM E N T
E R R O R S.
4 . A LL VA LV E S AT P R E SS U R E C O N N EC T IO N S S H O U L D B E IN N E A R LY V E RT IC A L
P O S IT IO N .
5 . D O N OT B LO W D OW N IM P U LS E P IP IN G T H R O U G H T R A N S M IT TE R . FL U S H LIN E S
W IT H VA LV E S "A " C LO S E D. R E F IL L L IN E S W IT H WAT ER B E F O R E R E S U M IN G
M E A S U R E M E N T.
G
1 /2 -IN .
T U B IN G
WBPEEUI110504A0
L OW E R IM P U LS E L IN E M U ST B E
B R O U G H T U P TO E L E VAT IO N O F
U P P E R IM P U LS E L IN E . M IN IM U M
ID 5/8 -IN . LAG F R O M M AIN L IN E
TO S H U TO F F VALV E S.
A
F
E
H I
F LO W
L O
C
B
B LO W -D O W N
VA LV E S
V ER TIC A L PIP E
Figure 3-4. Vapor Flow

CLOSED TANK LEVEL MEASUREMENT

In a closed vessel, pressure above the liquid affects the pres-
sure measured at the bottom of the vessel. It then becomes
necessary to subtract the pressure above the liquid from the
pressure at the bottom of the vessel. Instead of leaving the -
(low pressure) connection open to the atmosphere (as in open
tank level measurements), connect a pressure tap from the
tank above the maximum level to be measured to the low pres-
sure connection of the transmitter.
Closed Tank Level Measurement in Noncondensing
Atmospheres
If the atmosphere above the liquid is noncondensing, the pres-
sure line from the top connection to the low pressure connec-
tion of the cell is a dry leg. The transmitter responds only to
the pressure of the fluid measured at the lower tap of the tank
that connects to the + (high pressure) connection of the cell
1 /2 -IN . VA LVE S - S TE M S U P O R AT S L IG H T A N G L E . S TA G G E R
A
F O R C LE A R A N C E .
A D D IT IO N A L S E T O F VA LV E S R E Q U IR E D FO R L O N G C O N N EC TIN G
B L IN E S O R W H E N D E S IR A B L E TO M O U N T U N IT AT F LO O R LE V E L
TO P E R M IT S E RV IC IN G .
C
E Q UA L IZ IN G VA LV E .
2 -IN . S U P PO RT IN G P IP E (C U S TO M E R S U P P L IE D ).
D
P LU G S O R V E N T VA LV E S .
E
1 /2 -IN . N IP P LE S TO S ID E O F F LA N G E O R P IP E . L AG TO VA LV E S .
F
1 /2 -IN . N IP P LE S AT LE A S T 10 2 M M (4 IN .) LO N G .
G
1 /2 -IN . T E E S B O TH AT S A M E E LE VAT IO N .
H
F LO W
G A
D
E
–
+
B LO W -D O W N
VA LV E S
H O R IZO N TAL P IP E
SETUP AND PHYSICAL INSTALLATION
INSTALLATION
H I
F
1 /2 -IN .
L O
T U B IN G
D
–
C +
B
T 02 2 18 A
3 - 9