Endress+Hauser Liquicap T FMI21 Technical Information
TI393F/00/en
Technical Information
Liquicap T FMI21
Capacitive level measurement
Two-rod probe for continuous measurement in liquids
Application
The Liquicap T sensor is used in conductive liquids
(as of 30 µS/cm) for continuous level measurement and
is preconfigured from factory 0 %...100 % to probe length
ordered.
As of a conductivity of 30 µS/cm, the measurement is
independent of the dc-value (dielectric constant) of the
liquid. It can also be deployed in Ex area, Zone 2.
The Liquicap T is particularly suited to the following
applications:
• Small measuring ranges (as of 150 mm)
• Cistern measurements
• Aggressive liquids such as acids and alkalis
• Independent of the tank material (plastic, stainless
steel or concrete) or the tank shape
Used in conjunction with the Fieldgate FXA320 (remote
measured value interrogation using Internet technology),
Liquicap T is an ideal solution for inventorying material
and optimising logistics (inventory control).
Your benefits
• Safe function regardless of tank geometry thanks to
probe design
• No calibration necessary (preconfigured from factory
0 %...100 % to probe length ordered)
• High quality, non-corrosive materials (carbon fibre,
stainless steel) for use in aggressive liquids and liquids
which present a hazard to water (WHG-approved
(German Water Resources Law))
• No moving parts in tank - long operating life dependable function without wear
• Cost-effective solution for continuous measurement of
levels in conductive liquids
• Optimised storage by simply shortening the probe rods
on site (probe shortening set)
Liquicap T FMI21
2
Endress+Hauser
Table of contents
Function and system design. . . . . . . . . . . . . . . . . . . . . 3
Measuring principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Measuring system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Operating medium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Measured variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Measuring range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Input signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Electronic insert FEI20 (4...20 mA) . . . . . . . . . . . . . . . . . . . . . . . . 5
Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Electrical connection (wiring diagram) . . . . . . . . . . . . . . . . . . . . . 6
Transmitter power supply units from Endress+Hauser . . . . . . . . . . 6
Supply voltage (FEI20) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Power consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Current consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Cable entries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Cable specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Performance characteristics
with installed electronic insert . . . . . . . . . . . . . . . . . . 7
Reference operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Maximum measured error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Repeatability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Start-up settling time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Influence of ambient temperature . . . . . . . . . . . . . . . . . . . . . . . . . 7
Integration time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Factory calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Installation instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Ambient temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Ambient temperature limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Storage temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Climate class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Degree of protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Shock resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Vibration resistance (with min. rod length 150 mm) . . . . . . . . . . . 8
Electromagnetic compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Conductivity of medium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Process pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Mechanical construction . . . . . . . . . . . . . . . . . . . . . . 10
Design, dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Probe shortening set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Fitted electrodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Human interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Operating elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Display elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Certificates and approvals . . . . . . . . . . . . . . . . . . . . . 13
CE mark . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Overfill protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Other standards and guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Ex approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Type of protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Ordering information. . . . . . . . . . . . . . . . . . . . . . . . . 14
Liquicap T FMI21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Liquicap T . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Spare parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Technical Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Operating Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Certificates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Liquicap T FMI21
Endress+Hauser 3
Function and system design
Measuring principle The probe, medium and ground rod (counter electrode) form an electric capacitor.
If the probe is in the air ➀, a certain low initial capacitance is measured.
When the tank is filled, the capacitance of the capacitor increases the more the probe is covered ➁ ➂.
As of a conductivity of 30 µs/cm, the measurement does not depend on the dc-value of the liquid.
The electronic insert of the probe converts the capacitance measured to a current, in proportion to the level,
in the range of 4...20 mA, thus making it possible to interpret the level.
All input and output channels are safely galvanically isolated from one another.
L00-FMI21xxx-15-05-xx-xx-001
CA : Initial capacitance (probe exposed)
C
E
: Final capacitance (probe covered)
Measuring system Probe with integrated electronic insert
The measuring system consists of:
• The components of a capacitive probe Liquicap T FMI21:
➀ Housing with two probe rods
(one probe rod fully insulated and the second uninsulated (ground potential))
➁ Electronic insert FEI20
➂ Display (optional)
➃ Housing cover (optional: cover with sight glass in conjunction with display)
• A transmitter power supply unit
L00-FMI21xxx-14-05-xx-en-000
mn o
C
A
R
C
C
C
E
A
E
X
E
X
–+
– +
FEI20
1 2
+ –
–
+
m
n
o
p
ATEX II 3G
RN221N
RNS221
RMA421
RMA422
FXA320
FMI21
0…100%
100,0
Remote
interrogation
Liquicap T FMI21
4 Endress+Hauser
Operating medium Due to the probe design, the Liquicap T FMI21 can be used as of a conductivity of 30 µs/cm. The measurement
is independent of the dc-value and the conductivity of the liquid.
L00-FMI21xxx-05-06-xx-en-000
Applications Vendor Managed Inventory
The remote interrogation of tank or silo levels via Fieldgate enables suppliers of raw materials to gather
information about the current inventories of their regular customers at any time and, for example, take this into
account in their own production planning. The Fieldgate monitor the configured level limits and automatically
trigger the next delivery as required. Here, the spectrum of possibilities ranges from a simple purchasing
requisition by e-mail through to fully automatic order processing by incorporating XML data into the planning
systems on both sides.
L00-FMI21xxx-02-00-06-en-001
10
–3
10
–2
10
–1
1
10
10
2
10
3
10
4
30
Conductivity [µS/cm]
Liquicap T operating range
independent of the conductivity
and DK value (dielectric constant)
e.g. Hydrocarbons with
water contents below 0.1%,
petrols, oils, solvents
e.g. Hydrocarbons with
higher water contents,
demineralised water
e.g. Water-based liquids,
aqueous solutions of salts,
acids and alkalis,
aqueous dispersions and emulsions,
wastewater, electrolytes, beverages
Recommendation:
e.g. Multicap or Liquicap M
Levelflex M
Prosonic T/M
Micropilot M
Not suitable for Liquicap T
Fieldgate
FXA320
FMI21
Fieldgate
FXA320
Solar box with
FXA320
Solar panel
GSM
Vendor
Client A
Analog
4...20 mA
Analog
4...20 mA
Ethernet
Client B
Limit
switch
Telephone
Liquicap T FMI21
Endress+Hauser 5
Input
Measured variable Continuous measurement of the change in capacitance between two probe rods depending on the level of a
conductive liquid. Maximum viscosity = 2000 cst
Measuring range The measuring range is between 150...2500 mm, depending on the probe length ordered.
• Probe length: 150...2500 mm
• Adjustable initial capacitance: C
A
= 0...2000 pF
• Permitted span: ∆C = 25...2000 pF
• End capacitance: C
E
= max. 2100 pF
• Measuring frequency: 250 kHz
Input signal Probes covered => high capacitance
Probes exposed => low capacitance
Output
Electronic insert FEI20
(4...20 mA)
Output signal
3.8...20.5 mA
Switch-on current
Max. 20 mA (< 500 ms)
Signal on alarm
> 21 mA
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