13 Advantages of Magnetic Fuel Senders vs. Capacitive

Aircraft rely on precise and accurate measurement of fuel quantity to ensure safe and efficient operation.

In the aviation industry, there are several types of fuel senders used for this purpose. Here we will compare magnetic and capacitive fuel senders. While both types serve the same purpose, there are significant differences between them which can impact their performance and reliability in aviation applications. In this article, we will explore 13 advantages magnetic fuel senders have over capacitive fuel senders for aircraft fuel measurement. Understanding these advantages can help aircraft owners and operators make informed decisions about which type of fuel sender is best suited for their specific needs.

Magnetic Fuel Senders Advantages vs. Capacitive Fuel Senders

1. Fuel Quantity

Magnetic fuel senders measure the height of fuel in the tank or fuel volume in a non-electrical contact manner, resulting in no change in output. In contrast, capacitive fuel senders’ accuracy is degraded because of the differing electrical properties of the fuel.

2. Fuel Temperature

Magnetic fuel senders are not affected by fuel temperature stratification and do not require compensation. In contrast, capacitive fuel senders’ accuracy is degraded by fuel temperature stratification and requires compensation.

3. Entrained Air

Magnetic fuel senders are not affected by entrained air in the fuel, which can change its electrical properties. In contrast, capacitive fuel senders’ accuracy is degraded by entrained air and requires compensation.

4. Contamination

Magnetic fuel senders are mildly affected by contamination and are self-cleaning due to generous clearances that do not affect system accuracy. In contrast, capacitive fuel senders’ accuracy is slowly degraded by contamination, affecting the probe.

5. Fuel Motion

Magnetic fuel senders are not affected by fuel motion, including out-of-plane motion, as the float used dampens fuel motion. Similarly, capacitive fuel senders are not affected by fuel motion.

6. Safety

Magnetic fuel senders are intrinsically safe as there are no electronics in the fuel tank. In contrast, capacitive fuel senders are hazardous as there are electronics in the tank.

7. Damping

Magnetic fuel senders use a dense closed-cell float to dampen fuel movement, while capacitive fuel senders use small passages to dampen fuel movement.

8. Water in Fuel

Magnetic fuel senders are not affected by water in the fuel, as they have no electrical contact with the tank contents. In contrast, capacitive fuel senders are grossly degraded by water in the fuel.

9. Compatibility

Magnetic fuel senders can mount in existing fuel quantity locations, while capacitive fuel senders require a dedicated position and mounting.

10. Output Options

Magnetic fuel senders offer frequency, voltage, and resistance output options, while capacitive fuel senders offer only frequency and voltage output options.

11. Accuracy

Magnetic fuel senders have the highest accuracy available for fuel quantity measurement, exceeding 0.75%, with no measurable error or hysteresis in TSO testing. In contrast, capacitive fuel senders’ accuracy is limited to 3% for simple capacitive systems that are TSO’d. Better accuracy requires densitometers, permittivity measurement, and temperature compensation, which can make capacitive fuel senders less accurate. Non-TSO capacitive systems are typically less accurate.

12. Float Error

Magnetic fuel senders minimize float error, as buoyancy does not need to drive a mechanical interface, and they use smaller, denser floats. This is not an applicable problem for capacitive systems.

13. Corrosion

Magnetic fuel senders are not affected by corrosion, while capacitive fuel senders’ output is degraded.

14. Fuel Oscillation

Magnetic fuel senders are not affected by fuel oscillation, as they have physical and electronic damping. Similarly, capacitive fuel senders are not affected by fuel oscillation.

15. Complexity

Magnetic fuel senders are simple, while capacitive fuel senders are complex to meet safety and accuracy requirements.

Magnetic fuel senders offer numerous advantages over capacitive fuel senders when it comes to accurately measuring fuel quantity and ensuring safe and efficient operation of fuel tanks. With their simple design, high accuracy, and immunity to issues such as fuel temperature stratification, entrained air, and contamination, magnetic fuel senders provide a reliable solution for a variety of fuel measurement applications. Furthermore, their non-electrical contact measurement method and lack of electronic components in the fuel tank make them intrinsically safe, reducing the risk of hazards. Ultimately, the benefits of magnetic fuel senders make them a highly attractive option for all aircraft.

Would you like to view this comparison in a table format? Check out this page to view a table of magnetic vs. capacitive fuel senders.

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About CiES Inc.

Established in 2012, CiES is now the largest supplier of aviation fuel quantity probes and senders. They are the recognized leader in the design, development, certification, and manufacture of electronic sensor solutions for original equipment manufacturers, as well as direct-to-market consumer products. Through the creative application of cutting-edge technologies, CiES creates complex end-to-end solutions. This is a company that is changing the game in aviation technology and revolutionizing the way we navigate the skies. Aiming at future growth and innovation, CiES is pushing the boundaries of what is possible.​

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