FCL18 Liquid Level Control Relays
Single-phase liquid level monitoring relays for automatic tank filling and emptying control. Support 1-level and 2-level detection with adjustable sensitivity (5KΩ-100KΩ). Wide voltage input AC/DC 12-240V for industrial and commercial applications.
What is a Liquid Level Relay?
A Liquid Level Relay (also called Level Control Relay) automatically controls liquid levels in tanks and reservoirs by monitoring conductive probes. When liquid contacts or loses contact with the probe, the relay activates pumps or valves to maintain desired levels.
Fiicco FCL18 Series provides reliable liquid level control for water tanks, fuel tanks, sumps, and industrial process tanks. The relay can be configured for filling (adding liquid) or emptying (removing liquid) operations with 1-level or 2-level detection modes.
Control Functions
FCL18 supports multiple liquid level control modes for various applications
Function A - Fill (2-Level)
2-level control for automatic tank filling. Uses Max and Min probes to start/stop pump.
FCL18-02Function B - Fill (1-Level)
Single-level control for filling with adjustable time delay. Economical solution.
FCL18-02Function C - Fill (1-Level + Delay)
1-level control with enhanced time delay settings for complex filling sequences.
FCL18-02Function D - Empty (1-Level)
Single-level control for tank emptying with automatic shutdown at low level.
FCL18-02Function E - Empty (1-Level)
Single-level control for emptying with adjustable delay and automatic stop.
FCL18-02Function F - Empty (2-Level)
2-level control for safe tank emptying with high/low level protection.
FCL18-02 / FCL18-01FCL18 Model Comparison
Compare FCL18-01 and FCL18-02 liquid level relay specifications
| Specification | FCL18-01 | FCL18-02 |
|---|---|---|
| Control Mode | 2-level control | 1 or 2-level control |
| Functions | Function F (Empty liquid) | Function A/B/C/D/E/F (Fill & Empty) |
| Supply Voltage | AC 230V / DC 24V / AC/DC 12-240V | |
| Power Consumption | AC 3.5VA / DC 2.0W | |
| Voltage Tolerance | -15% ~ +10% | |
| Sensitivity Range | 5KΩ - 100KΩ (Adjustable) | |
| Output Contact | 1× SPDT 16A | |
| Time Delay Range | 0.1s - 10s | |
| Mechanical Life | 7 million operations | |
| Electrical Life | 100,000 operations (10A) | |
| Ambient Temperature | -20°C ~ +60°C | |
| Dimensions | 90mm × 18mm × 64mm | |
| Weight | 75g | |
| Standards | GB/T 14048.5, IEC60947-5-1, EN6812-1 | |
FCL18 Models
Choose the right model for your liquid level control application
FCL18-01
Dedicated 2-level control relay for tank emptying applications. Automatically starts pump when liquid is above high level and stops when reaching low level.
- Function F - 2-level empty control
- Adjustable sensitivity: 5KΩ-100KΩ
- Time delay: 0.1s-10s
- LED power & status indication
FCL18-02
Versatile liquid level control relay supporting 6 different functions for both filling and emptying applications. Perfect for complex tank management systems.
- 6 functions: A, B, C, D, E, F
- 1-level or 2-level control selectable
- Fill liquid or Empty liquid modes
- Adjustable sensitivity & time delay
Wiring Terminals
Terminal configuration for FCL18 liquid level relays
Power Supply
Control voltage input
Level Probes
Liquid level sensing
Output Contact
SPDT relay output
Technical Specifications
FCL18 liquid level relay specifications
Supply Voltage
AC 230V / DC 24V / AC/DC 12-240V
Power Consumption
AC 3.5VA / DC 2.0W
Sensitivity
5KΩ - 100KΩ
Output Contact
1× SPDT 16A
Time Delay
0.1s - 10s
Voltage Tolerance
-15% ~ +10%
Dimensions
90×18×64mm
Temperature
-20°C ~ +60°C
Key Features
Designed for reliable liquid level control
Adjustable Sensitivity
5KΩ to 100KΩ sensitivity range adapts to various liquid types
Multi-Function
6 control functions for filling and emptying applications
Wide Voltage
AC/DC 12-240V universal input for global compatibility
LED Indication
Green LED for power, Red LED for relay status
Level Probes (Accessories)
Liquid level probes are sold separately - order according to your tank depth
FCL-PB (Red)
1.5 meter probe cable
1.5m / 5ftFCL-PB (White)
2.5 meter probe cable
2.5m / 8ftFCL-PB (Blue)
3.5 meter probe cable
3.5m / 11.5ftHow It Works
Understanding FCL18 liquid level relay operation
Filling Mode (Function A/B/C)
FCL18 controls filling by monitoring liquid level with conductive probes.
- 1Install probes at desired high level (Max) and low level (Min) positions
- 2Set sensitivity (R) based on liquid conductivity
- 3Configure time delay (Tt) to prevent false triggering
- 4When liquid drops below Min → Pump starts → When liquid reaches Max → Pump stops
Emptying Mode (Function D/E/F)
FCL18 controls emptying by monitoring liquid level for safe drainage.
- 1Install probes at desired high level and low level positions
- 2Set sensitivity (R) appropriate for your tank and liquid
- 3Configure time delay (Tt) for smooth operation
- 4When liquid rises above Max → Pump starts → When liquid drops below Min → Pump stops
Common Applications
Widely used in liquid level control and management
Water Tanks
Residential & industrial water supply
Sump Pits
Basement and drainage pump control
HVAC Systems
Cooling tower and boiler water level
Irrigation
Agricultural water management
Fuel Tanks
Diesel and oil tank monitoring
Industrial Process
Chemical and manufacturing tanks
Why Choose Fiicco FCL18?
Compare our advantages against typical market alternatives
Fiicco FCL18 Advantages
- 6 control functions (A-F) for versatile applications
- Wide voltage input AC/DC 12-240V
- High EMI and vibration resistance
- No minimum order quantity
- Factory direct pricing
Typical Market Alternatives
- Limited to 2-3 control modes
- Fixed voltage options only
- Prone to interference in industrial environments
- High minimum order requirements
- Distributor markups
Frequently Asked Questions
What's the difference between FCL18-01 and FCL18-02?
FCL18-01 is designed specifically for 2-level emptying applications (Function F). FCL18-02 is more versatile, supporting 6 different control functions (A through F) for both filling and emptying with 1-level or 2-level control modes.
How do I choose the right sensitivity setting?
Sensitivity (R) should be set based on the conductivity of your liquid. For highly conductive liquids (like saltwater), use lower sensitivity (5-20KΩ). For less conductive liquids (like pure water), use higher sensitivity (50-100KΩ). Start at mid-range and adjust as needed.
How many probes do I need?
For 2-level control (Functions A/F), you need 3 probes: Common (C), Max level, and Min level. For 1-level control (Functions B/C/D/E), you need 2 probes: Common (C) and Level. The FCL-PB probes are sold separately - choose lengths based on your tank depth.
What is the purpose of the time delay?
Time delay (Tt) prevents false triggering from liquid splashing or wave action. Set Tt to 0.1-2s for fast-responding applications, or 2-10s for tanks with significant liquid movement. This ensures stable, reliable operation.
Can FCL18 work with different liquids?
Yes, FCL18 works with any conductive liquid that can complete a circuit between probes. Adjust the sensitivity setting based on liquid conductivity. Note: FCL18 is not suitable for non-conductive liquids like oils or chemicals that don't conduct electricity.
Ready to Order FCL18 Liquid Level Relay?
Contact Fiicco for pricing, sample orders, or technical support. Level probes sold separately. We ship globally with full technical documentation included.