A float switch is one of the most commonly used and reliable liquid level control devices in both industrial and residential applications. With its simple structure and stable performance, it is widely used in water tanks, towers, sewage pits, oil tanks, and chemical storage systems.
Whether for automatic pump control or high/low level alarms, float switches provide accurate and cost-effective solutions.
As a professional manufacturer of level control products, ELECALL has been focusing on the R&D and production of float switches and related instruments since 2008, providing cost-effective level control solutions to customers in over 30 countries and regions worldwide.
Working Principle of Float Switch
The core component of a float switch is the float (ball).
Inside the float, a magnet or counterweight is usually embedded. When the liquid level rises or falls, the float moves accordingly and drives an external reed switch to open or close via magnetic force, thus controlling the circuit.
The key advantage is that the float operates without external power, relying entirely on buoyancy. This makes it a passive device with high safety and reliability.
Types of Float Switches
1. Cable Float Switch (Most Common)
- Suspended by a cable in liquid, suitable for tanks, sewage pits, and sumps
- Advantages: easy installation, low cost, simple maintenance
- Available types: single, double, and triple float (multi-point control)
2. Side-Mounted Float Switch
- Installed on the side wall of a tank via thread or flange
- Ideal for limited space or where bottom installation is not possible
3. Rod-Type (Multi-Point) Float Switch
- Stainless steel rod with multiple floats fixed at different levels
- Used for complex control such as high-level alarm, low-level pump stop, and mid-level start
4. Stainless Steel vs PP Float Switch
- PP Float Switch
Corrosion-resistant, lightweight, cost-effective
Suitable for water, wastewater, weak acids/alkalis, and food-grade liquids - Stainless Steel Float Switch (SUS304/SUS316)
High temperature resistance (up to 200°C), high pressure resistance
Ideal for petrochemical, boiler, and harsh environments
Liquid Density Reference Table (20°C, Unit: g/cm³)
Understanding liquid density is critical, as the float density must be lower than the medium:
- Fresh water: 1.00
- Seawater: 1.02–1.03
- Diesel: 0.82–0.86
- Gasoline: 0.71–0.77
- Engine oil: 0.88–0.94
- Hydraulic oil: 0.85–0.90
- 30% NaOH: 1.33
- 30% sulfuric acid: 1.22
- Milk: 1.03
- Ethanol: 0.79
How to Select Float Density (Key Guide)
- For water (1.00): recommend ≤0.85 for reliable operation
- For oils (0.82–0.90): recommend ≤0.70–0.75
- For heavy chemicals (1.10–1.30): recommend ≤0.90–1.05
ELECALL Advantage:
Custom float density available from 0.30 to 1.10 g/cm³, covering almost all industrial liquids.
Installation Guidelines
- Ensure no obstacles within float movement range
- For cable types, fix the cable properly and allow at least 150 mm movement
- For side-mounted types, align installation height with control level
- Use stainless steel for high temperature, pressure, or corrosive media
- Use explosion-proof models in hazardous environments
Common Problems & Solutions
1. Float Does Not Move
Cause: incorrect float density or medium density change
Solution: reselect appropriate float density
2. No Electrical Output
Cause: damaged reed switch or demagnetized magnet
Solution: replace the float switch
3. Slow Response
Cause: high viscosity or small float size
Solution: use larger or lower-density float
4. Cable Damage
Cause: long-term exposure to corrosive liquid
Solution: use protected cable or stainless steel type
ELECALL Float Switch Advantages
- Full Material Range: PP and SUS304/SUS316 available
- Custom Density: 0.30–1.10 g/cm³
- Wide Selection: mini to large, single to multi-point
- Quality Assurance: CE, ROHS, ISO9001, explosion-proof certified
- Flexible Supply: OEM/ODM supported, MOQ 100 pcs
- Applications: water treatment, petrochemical, food & beverage, HVAC, fire protection, metallurgy
About ELECALL
Founded in 2008, ELECALL specializes in OEM/ODM manufacturing of industrial process measurement and control instruments.
Our product range includes sensors, transmitters, controllers, and switches for pressure, flow, temperature, and level measurement.
With ISO-certified facilities, advanced production systems, and complete testing laboratories, ELECALL products are known for reliability and precision. We serve industries such as water treatment, metallurgy, gas, fire protection, and petrochemical.
From small manufacturers to system integrators and distributors, ELECALL is your trusted global partner.
Contact Us
If you are looking for reliable float switches—whether PP, stainless steel, or customized density models—feel free to contact the ELECALL technical team.
We will provide professional selection guidance and quotations based on your application.
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