The Liquiphant FTL33 is a point level switch for universal use in all liquids. It is used
preferably in storage tanks, mixing vessels and pipes, where the internal and
external hygiene requirements are particularly stringent.
Ideal for applications in which float switches or conductive, capacitance and optical
sensors have been used up to now. The Liquiphant FTL33 also works in areas where
these measuring principles are not suitable due to conductivity, buildup, turbulence,
flow conditions or air bubbles.
The Liquiphant FTL33 can be used for process temperatures up to:
• 100 °C (212 °F), CIP-capable
• 150 °C (302 °F), CIP- and SIP-capable
Your benefits
• 3-A and EHEDG certificates
• CIP and SIP cleanability guaranteed up to 150 °C (302 °F)
continuous temperature
• All-metal separation, no plastics in the process
• Robust stainless steel housing, optionally available with M12x1 connector with
IP69 protection (optional)
• External function test with test magnet
• Onsite function check possible thanks to LED indication
• Compact design for easy installation even in confined conditions or hard-to-access
areas
This symbol alerts you to a dangerous situation. Failure to avoid this situation
will result in serious or fatal injury.
WARNING!
This symbol alerts you to a dangerous situation. Failure to avoid this situation
can result in serious or fatal injury.
CAUTION!
This symbol alerts you to a dangerous situation. Failure to avoid this situation
can result in minor or medium injury.
NOTE!
This symbol contains information on procedures and other facts which do not
result in personal injury.
SymbolMeaning
Ground connection
A grounded terminal which, as far as the operator is concerned, is grounded via a grounding
A0011200
system.
Protective ground connection
A terminal which must be connected to ground prior to establishing any other connections.
A0011199
Symbols for certain types of information
SymbolMeaning
Permitted
Indicates procedures, processes or actions that are permitted.
A0011182
Forbidden
Indicates procedures, processes or actions that are forbidden.
A0011184
Tip
Indicates additional information.
A0011193
Reference to documentation
Refers to the corresponding device documentation.
A0011194
Reference to page
Refers to the corresponding page number.
A0011195
Symbols in graphics
SymbolMeaning
1, 2, 3 ...Item numbers
A, B, C, ...Views
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Function and system design
2
1
3
Liquiphant FTL33
Measuring principle
Measuring system
A piezoelectric drive causes the tuning fork of the Liquiphant FTL33 to vibrate at its resonance
frequency. When the tuning fork is immersed in a liquid, its intrinsic frequency changes due to the
change in density of the surrounding medium. The electronics system in the point level switch
monitors the resonance frequency and indicates whether the tuning fork is vibrating in air or is
covered by liquid.
A signal is output via the DC-PNP or AC/DC electrical connection.
The measuring system consists of a Liquiphant FTL33 point level switch, e.g. for connection to
programmable logic controllers (PLC), a mini-contactor or solenoid valve.
1Overfill prevention or upper level detection MAX (maximum safety)
2Lower level detection MIN (minimum safety)
3Lower level detection MIN, e.g. dry running protection for pump
A0020911
4Endress+Hauser
Liquiphant FTL33
Input
Measured variable
Measuring range
Switch output
Operating modes
Density
> 0.7 g/cm³ (optionally available: > 0.5 g/cm³)
Output
Switching behavior: On/Off
Function
3-wire DC-PNP:
Positive voltage signal at the switch output of the electronics (PNP), switching capacity 200 mA
2-wire AC/DC:
Load switching in the power supply line, switching capacity 250 mA
The device has two operating modes: maximum safety (MAX) and minimum safety (MIN).
By choosing the corresponding operating mode, the user ensures that the device also switches in a
safety-oriented manner even in an alarm condition, e.g. if the power supply line is disconnected.
• Maximum safety (MAX)
The device keeps the electronic switch closed as long as the liquid level is below the fork. Sample
application: overfill prevention
• Minimum safety (MIN)
The device keeps the electronic switch closed as long as the fork is immersed in liquid. Sample
application: Dry running protection for pumps
The electronic switch opens if the limit is reached, if a fault occurs or the power fails (quiescent
current principle).
Supply voltage
Power consumption
Current consumption
Residual ripple
Electrical connection
Power supply
DC-PNP:
AC/DC:
DC-PNP:
AC/DC:
DC-PNP:
AC/DC:
DC-PNP:
AC/DC:
Two electronic versions and three different connections are available for the device.
• Electronic version 3-wire DC-PNP with connection; M12 plug, valve plug or cable
• Electronic version 2-wire AC/DC with connection; valve plug or cable
A fine-wire fuse is necessary for operation: 500 mA slow-blow.
Electronic version 3-wire DC-PNP
3-wire DC-PNP is preferably used in conjunction with programmable logic controllers (PLC), DI
modules as per EN 61131-2. Positive signal at the switch output of the electronics (PNP).
Voltage source: non-hazardous contact voltage or Class 2 circuit (North America).
10 to 30 V DC, 3-wire
20 to 253 V AC/DC, 2-wire
< 975 mW
< 850 mW
< 15 mA
< 3.8 mA
5 Vss 0 to 400 Hz
—
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Liquiphant FTL33
0.5A
L– L+
2
1
3
4
K
0.5A
L–
L+
2
1
3
4
K
1
21
2
1
41
4
0.5A
L–L+
2
1
3
4
K1
K2
1
2
1
4
4
1
12
21
41
Connection with M12 plug
Depending on the analysis of the switch outputs, the device works in the MAX (maximum safety) or
MIN (minimum safety) mode.
A cable is optionally available for order, see "Accessories" section → 31.
3-wire DC-PNPOperating mode
M12 connectorMAXMIN
A0022901
SymbolsKDescription
Yellow LED (ye) lit
Yellow LED (ye) not lit
external load
Function monitoring with M12 connector
Using a two-channel analysis, function monitoring of the sensor can be implemented in addition to
level monitoring, e.g. per relay switch, PLC, AS-i Bus I/O module, …).
When both outputs are connected, the MIN and MAX outputs assume opposite states when the
device is operating fault-free (XOR). In the event of an alarm condition or a line break, both outputs
are deenergized.
Connection with 3-wire DC-PNP for function monitoring based on XOR logic
Sensor covered
Sensor exposed
Fault
A0022917
Symbols
K1 / K2
Description
LED lit
LED not lit
Fault or warning
external load
Yellow LED
(ye)
Red LED
(rd)
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Liquiphant FTL33
1
3
0.5A
L–
L+
2
K
+
–
L–
L+
3
0.5A
1
2
K
+
–
3
23
2
2323
0.5A
1
2
3
L–
L+
K
+
L+
0.5A
K
1
2
3
L–
+
3
23
2
2323
Connection with valve plug or cable
Depending on the assignment of the connector or the wiring of the cable, the device works in either
the MAX or MIN operating mode.
3-wire DC-PNPOperating mode
Valve plugMAXMIN
A0022900
Cable (cannot be
dismantled)
Core colors:
1 = BK (black)
2 = GR (gray)
3 = BN (brown)
Ground = GNYE (greenyellow)
SymbolsKDescription
Yellow LED (ye) lit
Yellow LED (ye) not lit
external load
A0022902
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Liquiphant FTL33
2.7
2.5
2.3
2.1
1.9
1.7
1.5
1.3
1.1
0.9
0.7
0.5
20242743485360110121 207 230 253
P/S
U
P1
P2
Electronic version 2-wire AC/DC
The load is switched via an electronic switch directly in the power supply circuit. Always connect in
series with a load!
Not suitable for connection to low-voltage PLC inputs!
Selection tool for relays
1Minimum rated power of the load
P/S Rated power in [W] / [VA]
UOperating voltage in [V]
ItemSupply voltage
P1
AC mode
P2
DC mode
24 V
110 V
230 V
24 V
48 V
60 V
minmax
> 1.3 VA
> 1.5 VA
> 2.5 VA
> 0.7 W
> 0.9 W
> 1.5 W
Rated power
< 6 VA
< 27.5 VA
< 57.5 VA
< 6 W
< 12 W
< 15 W
Relays with a lower rated power can be operated by means of an RC module connected in parallel
(optional).
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Liquiphant FTL33
3
0.5A
1
K
>20 V
L1/L+N/L–
2
0.5A
1
K
>20 V
L1/L+N/L–
1313
1
21
2
3
L1/L+
0.5A
K
>20 V
1
2
N/L–
1
L1/L+
0.5A
K
2
3
N/L–
>20 V
1313
1
21
2
A
B
C
Connection with valve plug or cable
Depending on the assignment of the connector or the wiring of the cable, the device works in either
the MAX or MIN operating mode.
When the cable is wired, one wire of the cable does not have any function in each of the operating
modes (brown in the case of MIN, and gray in the case of MAX). The cable with no function must be
secured against inadvertent contact.
2-wire AC/DCOperating mode
Valve plugMAXMIN
Cable entry
Cable (cannot be dismantled)
Core colors:
1 = BK (black)
2 = GR (gray)
3 = BN (brown)
Ground = GNYE (green-yellow)
SymbolsKDescription
Yellow LED (ye) lit
Yellow LED (ye) not lit
external load
A0022900
A0022902
A0021219
A0021418
A0022161
A0021418
A0021220
A0021420
A0022225
A0021420
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A0020928
AValve plug (M16x1.5; NPT ½"; QUICKON)
BM12 connector
CCable 5 m (16 ft); secured in place on delivery and cannot be disassembled
Liquiphant FTL33
Cable specification
Overvoltage protection
• Valve plug
– Cable cross-section: max. 1.5 mm2 (AWG 16)
– Ø 3.5 to 8 mm (0.14 to 0.26 in)
• M12 connector: IEC 60947-5-2
• Cable (3LPE)
– Cable cross-section: 0.75 mm2 (AWG 20)
– Ø 6 to 8 mm (0.24 to 0.31 in)
– Material: PUR