What Is Rotary Paddle Bin Level Switch

Rotary paddle bin level switch is used to detect the level of bulk solid materials in silos, hoppers and bins.

It ensures stable material management by providing reliable signals to control filling, discharge and process operations.

Working Principle of Rotary Paddle Level Switch

The rotary paddle level switch uses an electric motor to drive a paddle blade to rotate continuously.

When bulk material reaches the paddle position, the rotation is blocked due to material resistance. This triggers the internal control mechanism, generating an electrical signal to indicate material presence.

When the material level drops and the paddle is released, the spring mechanism restores rotation, allowing continuous monitoring of material level changes.

rotary paddle bin level switch for silo    

Key Features of Rotary Paddle Level Switch

  • Uses rotary paddle technology for reliable bulk material detection
  • Equipped with precision mechanical seals to prevent dust entering along the shaft
  • Spring clutch protection mechanism prevents motor damage under overload conditions
  • Modular design allows maintenance without complete disassembly
  • Available with custom paddle designs for low-density materials
  • Simple structure with easy installation and connection

bin level sensor sensitivity adjustment  grain bin level indicator

Technical Specifications of Rotary Paddle Level Switch

The following table shows the typical technical data for reference:

  • Voltage: 220VAC, 110VAC, 24VAC and 24VDC
  • Contact Capacity: 250VAC/5A (Negative Load), SPDT (Single Pole Double Throw)
  • Working Temperature: -30°C to 80°C
    • Standard high-temperature type: up to 200°C
    • Customized high-temperature type: up to 800°C
  • Powder: 3W
  • Rotating Torque: 1N · m
  • Blade Paddle Rotational Speed: 1RPM
  • Blade Paddle Material: SUS304
  • Protection Grade: IP65
  • Cable Entry: M20x1.5
  • Suitable Material Density: >=0.4g/cm3

level switch installed on hopper wall

Applications of Rotary Paddle Level Switch

Rotary paddle level switches are widely used in industries handling bulk materials, including:

  • Grain storage and processing
  • Cement and building materials
  • Mining and metallurgy
  • Chemical industry
  • Power plants
  • Food processing

They are suitable for powders, granules and bulk solids in silos and hoppers.

Advantages in Silo Level Monitoring

The rotary paddle level switch provides a simple and reliable solution for material level control.

It helps:

  • Prevent silo overfilling
  • Avoid empty running of equipment
  • Improve process automation
  • Ensure stable production operation

SR2 Rotary Paddle Level Switch – Model Variants

SR2-10S Rotary Paddle Level Switch

Standard Screw Type

Vertical and Horizontal Installation are both Acceptable

SR2-10S level switch-screw type

SR2-10F Rotary Paddle Level Switch

Standard Flange Type

Vertical and Horizontal Installation are both Acceptable

SR2-10F level switch-flange type

SR2-20F Rotary Paddle Level Switch

Axis Protection Tube Type

Vertical and Horizontal Installation are both Acceptable

SR2-20F paddle level switch-axis protection tube type

SR2-20F-T Rotary Paddle Level Switch

Axis Protection Tube and High-Temperature Type

Vertical and Horizontal Installation are both Acceptable

SR2-20F-T level switch-axis protection tube and high temperature type

SR2-30F Rotary Paddle Level Switch

Adjustable Axis Length Type

Only for Vertical Installation

SR2-30F silo switch level- adjustable axis length type

SR2-40F Rotary Paddle Level Switch

Steel Cable Type

Only for Vertical Installation

SR2-40F level switch silo-steel cable type

SR2-20F-H Rotary Paddle Level Switch

Special High-temperature Type (Max 800℃)

Vertical and Horizontal Installation are both Acceptable

SR2-20F-H silo level indicator-high special high temperature type

SR2-10XLT Rotary Paddle Level Switch

Specially Customized

Vertical and Horizontal Installation are both Acceptable

SR2-10XLT grain bin level monitoring-specially customized

SR7-10 Rotary Paddle Level Switch

Standard Explosion Proof Type

Vertical and Horizontal Installation are both Acceptable

SR7-10 grain bin level sensors-standard explosion-proof type

SR2-10F-L Rotary Paddle Level Switch

Straight Rod Extension Type

Only for Vertical Installation

SR2-10F-L silo level indicator-straight extension type

SR2-XLT Rotary Paddle Level Switch

Special Square Shape, Standard Screw Type

Vertical and Horizontal Installation are both Acceptable

SR-XLT GRAIN SILO LEVEL SENSOR-square standard screw type

Model Selection Guide for SR2 Rotary Paddle Level Switch

Selecting the right model is important to ensure accurate level detection and reliable operation.

Key Factors for Model Selection

  • Material type – powder, granules or bulk solids
  • Material density – low-density materials may require special paddle design
  • Installation position – top, side or angled mounting
  • Working temperature – standard or high-temperature environment
  • Silo or hopper size – determines shaft length and motor power

Typical Model Selection Reference

Model Type Suitable Application Key Feature
Standard Type General bulk materials Standard performance, cost-effective
Extended Shaft Type Deep silo or long insertion Longer shaft for deeper detection
High Temperature Type High temperature environments Heat-resistant design
Small Paddle Type Low-density materials Higher sensitivity
Heavy-Duty Type High-density or heavy materials Stronger torque and durability

Final Recommendation

If you are not sure which model is suitable, please send us your material type, density, silo size and working conditions.

We will recommend the most suitable SR2 model for your application.

Model Selection Guide for SR2 Rotary Paddle Level Switch

rotary paddle level switch

For Example SR2-10SAA-0800

Means: Standard Screw Type, 220VAC, A Type 100x40mm Rotary Paddle, total length 800mm.

Available Types of Silo Level Switches and Sensors

We offer a wide range of level detection solutions for silo and bin applications, including:

  • Rotary Paddle Level Switch
  • Small Rotary Paddle Level Switch
  • Capacitance Level Switch
  • RF Admittance Level Sensor
  • Radar Level Sensor and Ultrasonic Level Sensor
  • Weighing Level Sensor
  • Pneumatic Hammer and Vibrator

Installation and Application Areas

The level switch is typically installed on:

  • Silo side walls
  • Hopper walls
  • Storage bins

It can be used for high-level and low-level detection depending on the installation position.

Widely used in processing and conveying equipment in industries including grain, feed, seed, cement, plastics, construction and chemical processing.

Installation Guidelines for Silo Level Switch

To ensure proper operation and long service life, please follow the installation guidelines below:

installation precaution of level switch of grain bin

1. Power Supply Check

Please confirm the correct power supply before installation to avoid damage to the motor.

2. Installation Position

Install the level switch away from the material inlet to prevent direct impact from falling materials.

3. Cable Direction and Sealing

  • For horizontal installation, ensure the cable entry is facing downward
  • For vertical installation, also ensure the cable is directed downward (refer to the diagram)

Secure the cable gland and junction box cover tightly to prevent rainwater, dust or foreign matter from entering the unit.

4. Installation Angle (Horizontal Mounting)

For horizontal installation, it is recommended to mount the level switch with a downward inclination of 15–20°.

This helps reduce material accumulation around the paddle.

5. Protection for Lower Installation Position

When the level switch is installed in a lower position, a protective plate is recommended to prevent damage from material impact.

A semi-circular protective tube can be used:

    • At least 50 mm longer than the level switch
    • Installed approximately 250 mm above the switch
    • Fixed or welded in position for effective protection

Maintenance and Troubleshooting

Proper maintenance and timely troubleshooting can ensure stable operation and extend the service life of the level switch.

Routine Maintenance

  • Regularly check the paddle rotation condition to ensure it operates smoothly
  • Inspect the sealing parts and cable entry to prevent dust or moisture ingress
  • Clean any material build-up around the paddle to avoid false signals
  • Periodically check the electrical connections for safety and reliability

Common Issues and Solutions

1. Paddle does not rotate

  • Check power supply and wiring connections
  • Inspect whether the motor is damaged
  • Ensure no material blockage is preventing rotation

2. False level signal (incorrect detection)

  • Check if material has accumulated around the paddle
  • Verify whether the paddle type is suitable for the material density
  • Adjust installation position or angle if necessary

3. No signal output

  • Check electrical contact and control system
  • Verify switch contact capacity and connection status
  • Inspect internal components for damage

4. Frequent overload or motor protection activation

  • Check if material density is too high
  • Ensure proper paddle selection
  • Inspect for excessive material impact

Maintenance Recommendation

For long-term stable operation, it is recommended to perform regular inspection and cleaning, especially in environments with high dust, moisture or sticky materials.

Related Products for Silo & Bin Systems

Bin level sensors

 

  1. RF Admittance Sensor
  2. Rotary Paddle Level Switch
  3. Rotary Paddle Level Switch
  4. Radar Sensor
  5. Sensing Weight Level Sensor
  6. RF Admittance Level Sensor
  7. Digital Displayer
  8. Small Rotary Paddle Level Switch
  9. Rotary Paddle Level Switch
  10. Capacitance Sensor Level Switch
  11. Pneumatic Hammer
  12. Pneumatic Vibrator

Custom Level Detection Solution

Different materials and working conditions require different paddle designs and configurations.

We can provide customized solutions based on your material density, silo size and operating conditions.

Related Products for Silo Level Detection and Material Flow

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Ensure Reliable Material Level Control Today

Looking for a dependable solution to monitor material levels in your silo or hopper?

Send us your material type, silo size and working conditions. We will recommend the most suitable rotary paddle level switch for your application.

If you encounter any issues during operation, feel free to contact us for technical support.

Contact us today for a quick recommendation and quotation.