Fujimoto FKK 4 User Manual
48
Pressure measurement (in case of gas)
Mount the transmitter above the process pipes to
preventing moisture from entering the inside of
transmitter.
preventing moisture from entering the inside of
transmitter.
Level measurement
(1) In case of wet leg:
For measurement, connect the highest liquid level tapping of tank with the low pres-
sure side of transmitter, and the lowest liquid level tapping of tank with the high
pressure side of transmitter.
sure side of transmitter, and the lowest liquid level tapping of tank with the high
pressure side of transmitter.
< Level calculation formula >
LRV: rH
2
- r
0
H
1
URV: rH
2
+ r
1
h - r
0
H
1
Span (DP): r
1
h
LRV: Low limit of measurement (0% point)
URV: High limit of measurement (100% point)
r
URV: High limit of measurement (100% point)
r
0
,r,r
1
: Density
H
1
, H
2
: Liquid level, h: Liquid level change
(2) In case of dry leg:
For an open tank, leave the low pressure side of transmitter open to atmosphere.
< Level calculation formula >
LRV: rH
1
URV: rH
1
+ r
1
h
Span (DP): r
1
h
LRV: Low limit of measurement (0% point)
URV: High limit of measurement (100% point)
r,r
URV: High limit of measurement (100% point)
r,r
1
: Density
H
1
: Liquid level, h: Liquid level change
Stop valve
Process pipe
Pressure source
Manifold valve
Impulse pipe
Atmospheric
air inlet
air inlet
H
1
H
2
Max. liquid
level
Min. liquid
level
Condensor
ρ
0
ρ
Manifold
valve
valve
High
pressure
side
pressure
side
Low
pressure
side
pressure
side
h
ρ
1
H
1
Max. liquid
level
Min. liquid
level
Manifold
valve
valve
High
pressure
side
pressure
side
Low
pressure
side
pressure
side
Atomospheric
air inlet
air inlet
h
ρ
1
ρ
5
6
(1) Protection is required to prevent dust from entering through the atmospheric
air inlet after installation of the manifold valve.
(2) If process pressure range is narrow (below 10kPa (1000mmH
2
O)), the follow-
ing should be considered.
• Pressure variation due to wind around atmospheric air inlet
• Temperature variation near process taps
• Difference in atmospheric pressure between process tap and transmitter
• Temperature variation near process taps
• Difference in atmospheric pressure between process tap and transmitter
location.
To overcome this, provide atmospheric pressure-side pipe with a proper orifice
and consider accommodating the transmitter and atmospheric air inlet in a box.
and consider accommodating the transmitter and atmospheric air inlet in a box.
Important