Comprehensive Guide to Optical Fluid Level Switches

Optical fluid level switches detect the presence or absence of liquids rather than measuring exact fluid levels. Due to the variety of options available, selecting the appropriate fluid level sensor can be challenging. This technical overview guides engineers through the key considerations for choosing the best optical fluid level switch based on application requirements, environmental conditions, and sensor characteristics.

Key Considerations: Application and Environment

Understanding the broader context where the sensor will operate is critical for ensuring optimal performance:

• Mounting Location: The physical space available for installation can limit sensor size and mounting options.
• Application Industry: Different sectors—such as food and beverage, medical, or chemical processing—impose specific hygiene and chemical compatibility standards.
• Environmental Conditions: Consider fluid properties (corrosive, abrasive, temperature extremes), pressure, and exposure to aggressive chemicals, which influence material compatibility and sensor lifespan.

Step 1: Selecting Sensor Materials

Material selection is crucial in sensor durability, especially when exposed to corrosive fluids or harsh environments. Typical materials include:

• Housing Options: Polysulfone, Trogamid® (EU food-contact grade), or stainless steel.
• Sensing Tip Options: Polysulfone, Trogamid®, or glass.

The sensor housing and sensing tip are often made from different materials to optimize performance against mechanical stress and chemical exposure.

Step 2: Fluid Level Switch Types and Technical Specifications

Fluid level switches vary significantly in voltage ranges, temperature tolerances, and mechanical design, tailored to diverse industrial needs:

Optomax Digital

• Operating Voltage: 4.5V to 15.4V DC
• Temperature Range: -25°C to +80°C (standard); extended range to -40°C to +125°C
• Applications: Designed for space-constrained applications requiring miniature, low-power digital liquid presence detection.
• Materials: Polysulfone or Trogamid®

Optomax Industrial

• Operating Voltage: 4.5V to 15.4V DC or 8V to 30V DC
• Temperature Range: -25°C to +80°C; extended to -40°C to +125°C
• Applications: Suitable for industrial environments requiring high-power signalling capable of driving loads up to 1A.
• Materials: Polysulfone or Trogamid®

Optomax Industrial Glass

• Operating Voltage: 4.5V to 15.4V DC or 8V to 30V DC
• Temperature Range: -40°C to +125°C
• Applications: Engineered for aggressive chemical environments, featuring stainless steel housings with glass sensing tips to withstand corrosive fluids.
• Materials: Stainless steel body, glass sensing tip

LLHP (High Performance) Series

• Operating Voltage: 4.5V to 15.4V DC or 10V to 45V DC
• Temperature Range: -25°C to +80°C; extended to -40°C to +125°C
• Applications: Built for harsh environments with robust stainless steel housings and larger mounting threads; supports high switching currents and customizable thread options.
• Materials: Stainless steel housing with Polysulfone tip

POS Glass Tip Series

• Operating Voltage: 12V to 28V DC
• Temperature Range: -25°C to +100°C; extended to -40°C to +140°C
• Applications: It is designed for extreme industrial and chemical environments. The stainless steel housing is combined with a Simax crystal glass sensing tip for enhanced chemical resistance.
• Materials: Stainless steel body with glass sensing tip

Optomax Basic

• Operating Voltage: 3.3V to 24V DC
• Temperature Range: -25°C to +80°C
• Applications: Cost-effective analogue optical sensor for high volume OEM applications such as vending machines, white goods, and automotive. Requires a clean power supply and an external microcontroller for signal interpretation.
• Materials: Polysulfone or Trogamid®

Step 3: Testing and Validation

Once sensor options are narrowed, performance must be validated by testing samples within the actual fluid and operating conditions. Typical testing protocols involve submerging the sensor fully in the target liquid at maximum temperature for a minimum of two weeks to ensure reliable detection and material compatibility.

Technical Assistance

If sensor selection remains unclear, consulting application engineers with expertise in fluid level detection can provide tailored recommendations based on specific operating parameters and environmental challenges.

Conclusion

Selecting the optimal optical fluid level switch depends on thoroughly understanding the application environment, fluid properties, and technical requirements such as operating voltage and temperature. Engineers can ensure reliable and accurate liquid presence detection in demanding industrial settings by carefully evaluating sensor materials and performance characteristics. Rigorous testing and expert consultation further guarantee sensor compatibility and long-term durability.

For more information on our range of Liquid Level sensors, please contact one of our highly trained engineers today.