In industrial facilities, monitoring the level of liquids, solids, or semi-solids in tanks and pipelines is essential for process safety and efficiency. Level switches are widely used to prevent overflow, protect pumps from dry running, and maintain safe operation. Unlike continuous level transmitters, level switches are point-level devices that generate on/off signals at predefined levels.
WORKING PRINCIPLE
A level switch detects when a medium reaches a set height and provides a switching signal. This signal can activate pumps, valves, alarms, or shutdown systems.
Types include:
- Float switches
- Capacitive switches
- Ultrasonic switches
- Thermal switches
- Tuning fork switches
TYPES OF LEVEL SWITCHES
- Float type
- Magnetic type
- Capacitive type
- Ultrasonic type
- Tuning fork type
- Thermal type
APPLICATION AREAS
- Water and wastewater treatment
- Food and beverage
- Chemical and petrochemical
- Energy and boiler systems
- Bulk material silos
ADVANTAGES
- Reliable and simple operation
- Wide application range
- Prevention of critical incidents
- Low maintenance
LIMITATIONS
- Only point-level detection
- May be affected by foam or buildup
- Require special designs for extreme conditions
TECHNICAL SELECTION CRITERIA
- Process media properties
- Temperature and pressure
- Sanitary requirements
- Hazardous environment certifications
- Mounting method
ENGINEERING NOTE AND EXAMPLE
In a tank with a high level set at H = 2.5 m, a float level switch activates at this point:
- Pump stops
- Alarm is triggered
- Overflow risk is eliminated
RECOMMENDED LEVEL SWITCHES BY APPLICATION
| Application | Recommended Type | Advantage |
|---|---|---|
| Water storage | Float | Simple and cost-effective |
| Chemical tanks | Capacitive / Ultrasonic | Corrosion-resistant, contactless |
| Steam boilers | Thermal | Reliable low-level detection |
| Powder silos | Tuning fork | Not affected by dust |
| Food processing tanks | Hygienic capacitive | CIP/SIP compatible |
CONCLUSION
Level switches are essential point-level detection devices that enhance process safety and reliability. With proper selection and installation, they deliver dependable performance in diverse industries.