Float switches are essential components in industrial automation and residential liquid level control systems. The float ball (also known as a float) directly determines buoyancy, switching sensitivity, and media compatibility. Whether in water treatment, petrochemical, food & beverage, wastewater systems, or boiler tanks, selecting the correct float material, density, and size can significantly improve system stability and service life.
As a professional industrial instrumentation manufacturer, ELECALL has been focusing on the R&D, production, and sales of process measurement and control instruments since 2008. We offer a full range of float switch products—from lightweight PP floats to high-pressure stainless steel floats—serving customers in over 30 countries worldwide.
Working Principle of Float Switch Float Balls
Float balls typically contain built-in magnets or weighted structures. As the liquid level rises or falls, the float moves accordingly and actuates a reed switch through magnetic coupling or mechanical linkage. This enables functions such as high/low level alarms, pump control, and valve operation.
Float density (specific gravity) is the key parameter:
- The float density must be lower than the liquid density to ensure proper buoyancy.
- If the float density is too high, it will sink and fail.
- If too low, it may become unstable or less responsive in viscous or low-density liquids.
Common Liquid Density Reference Table (at 20°C, unit: g/cm³)
Below are typical density values of common industrial liquids to help match float density:
- Fresh water: 1.00
- Seawater: 1.02 – 1.03
- Diesel: 0.82 – 0.86
- Gasoline: 0.71 – 0.77
- Lubricating oil: 0.88 – 0.94
- Hydraulic oil: 0.85 – 0.90
- 30% NaOH (Sodium Hydroxide): 1.33
- 30% Sulfuric acid: 1.22
- Milk: 1.03
- Ethanol: 0.79
Note: Actual density may vary depending on temperature, concentration, and impurities. Always refer to real measured values for accurate selection.
How to Select Float Density
The key principle is:
Float density should be significantly lower than the liquid density, typically with a 10%–20% buoyancy margin.
Recommended Density Selection:
- Water (density ~1.00):
Float density ≤ 0.85 for stable and sensitive operation - Fuel/Oil (density 0.82 – 0.90):
Float density ≤ 0.70 – 0.75 to prevent sinking or sluggish response - Heavy chemical liquids (density 1.10 – 1.30):
Float density ≤ 0.90 – 1.05
ELECALL Advantage:
We offer custom float densities from 0.30 to 1.10 g/cm³, covering nearly all industrial liquid types—from low-density fuels to high-density chemical solutions.
PP Float vs Stainless Steel Float
1. PP Float (Polypropylene Float)
PP floats are lightweight, corrosion-resistant, and cost-effective.
Advantages:
- Excellent resistance to acids and alkalis
- Good insulation properties
- Wide adjustable density range
- Typical temperature range: 60–80°C (higher for reinforced types)
Common Density & Sizes:
- Low density (0.5–0.7): suitable for diesel, oil, ethanol
- Medium density (0.8–0.9): suitable for water and wastewater
- Sizes: from Φ25mm to Φ90mm
Applications:
- Normal temperature and pressure environments
- Corrosive but non-high-pressure conditions
2. Stainless Steel Float (SUS304 / SUS316)
Stainless steel floats are designed for harsh industrial environments.
Advantages:
- High mechanical strength
- Temperature resistance up to 200°C+
- Excellent pressure resistance
- SUS316 offers better corrosion resistance (especially to chlorides)
- Long service life
Common Density & Sizes:
- Standard density: ~0.85–0.95
- Diameter range: Φ28mm to Φ125mm
- Lower density versions available via structural optimization
Applications:
- High temperature and high-pressure systems
- Petrochemical, metallurgy, gas, and industrial processing
Float Density & Size Selection Guidelines
- Match float density with liquid density (ensure sufficient buoyancy margin)
- Consider liquid properties:
- Corrosive → PP or SUS316
- High temperature/pressure → Stainless steel
- High viscosity → Larger diameter float
- Food-grade → Food-grade PP or SUS304
- Installation space:
- Small tanks → small floats
- Large tanks → larger floats
ELECALL Custom Capability:
- Density range: 0.30 – 1.10 g/cm³
- Custom sizes available
- OEM/ODM supported
- MOQ starting from 100 pieces
Tips:
- For viscous liquids, choose larger and lower-density floats
- For media containing metal particles, consider magnetic interference
Advantages of ELECALL Float Balls
- Full product range: PP and stainless steel floats with customizable density and size
- High quality assurance: 15,000㎡ factory, advanced production equipment, full testing lab
- Certifications: CE, ROHS, ISO9001, Explosion-proof
- Global export: 30+ countries (Europe, Southeast Asia, Middle East, Americas)
- Flexible service: Fast response, low MOQ, OEM/ODM support
- Wide applications: Water treatment, metallurgy, gas, fire protection, petrochemical, food processing
About ELECALL
Since 2008, Yueqing ELECALL Electric Co., Ltd. has been a trusted OEM/ODM manufacturer specializing in industrial process measurement and control instrumentation.
We focus on the development and production of:
- Sensors
- Transmitters
- Controllers
- Switches
Our solutions cover:
- Pressure
- Flow
- Temperature
- Level measurement and control
With an ISO-certified factory, advanced production systems, and a complete in-house testing laboratory, ELECALL products are known for their stability and precision. We serve industries including water treatment, metallurgy, gas, fire protection, and petrochemicals.
From small manufacturers to system integrators and distributors, ELECALL is your reliable global partner for industrial automation components.
Contact Us
Looking for PP floats, stainless steel floats, or float switches matched to specific liquid densities?
Contact the ELECALL technical team today for professional selection guidance and customized liquid level control solutions.
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