MAGNETIC FIELD FUEL LEVEL SENDER
Fuel Sender Technology People Can Trust.
Fuel Sender technology has been stable over the last 80 years and while there are recent advances in alternate technology, the legacy method to measure fuel in aircraft has been:
- Capacitive
- Resistive
Two other recent technologies include:
- Ultrasonic
- Reed Switch
How does magnetic field fluid level compare to these four technologies? View the four charts below to find out:
Magnetic Field vs. Capacitive
| Characteristic | Magnetic Field | Capacitive |
|---|---|---|
| Fuel Quality | No change in output as only fuel height in the tank or fuel volume is measured in a non-electrical contact manner. The fuel is not a part of the fuel measurement circuit. | Accuracy is degraded, due to the differing electrical properties of the fuel |
| Fuel Temperature | No change in output as only fuel height in the tank or fuel volume is measured in a non-electrical contact manner. The fuel is not a part of the fuel measurement circuit. | Accuracy is degraded - Requires compensation. Fuel temperature stratification will adversely affect accuracy. |
| Entrained Air | No change in output as only fuel height in the tank or fuel volume is measured in a non-electrical contact manner. The fuel is not a part of the fuel measurement circuit. | Accuracy is Degraded - Requires Compensation. As Fuel with entrained air has a different and changing electrical property |
| Contamination | Mildly Effected - Self cleaning due to generous clearances that do not effect system accuracy | Affects Probe - Accuracy is slowly degraded |
| Fuel Motion | No Effect on Sensor. Out of Plane Motion has No Effect. Dense closed cell float utilized dampens fuel motion. | No Effect on Sensor |
| Safety | No Electronics in the Fuel Tank - No hazard intrinsically safe. | Electronics in the Tank - Hazard |
| Damping | Float size is minimized and density is increased which dampens fuel movement | Small Passages Dampens Fuel Movement |
| Water in Fuel | No Change in Output - No Electrical Contact with the fuel tank contents. | Sender is Grossly Degraded |
| Compatibility | Mounts in Existing Fuel Quantity Locations | Needs a Dedicated Position and Mounting |
| Output | Frequency, Voltage, Resistance | Frequency, Voltage |
| Accuracy | Highest accuracy available for fuel quantity measurement. Exceeds 0.75% - No measurable error or hysteresis in TSO testing. | Accuracy of simple capacitive systems that are TSO’d are 3%. Densitometers, Permittivity measurement and temperature compensation required for better accuracy. Non TSO Capacitive systems are typically less accurate. |
| Float Error | Minimized as float buoyancy does not need to drive a mechanical interface. Smaller and denser floats are utilized in Magnetic Field fuel quantity systems | No issue, not applicable |
| Corrosion | No effect on fuel level output | Degrades Output |
| Fuel Oscillation | No Issue - physical and electronic damping | No Issue - typically has physical and electronic damping |
| Complexity | Simple | Complex to meet safety and accuracy requirement |
Magnetic Field vs. Resistive
| Characteristic | Magnetic Field | Resistive |
|---|---|---|
| Fuel Quality | No change in output as only fuel height in the tank or fuel volume is measured in a non-electrical contact manner. The fuel is not a part of the fuel measurement circuit. | No change in output, the measurement method is typically immersed in fuel. Similar volume measurement. |
| Fuel Temperature | No change in output as only fuel height in the tank or fuel volume is measured in a non-electrical contact manner. The fuel is not a part of the fuel measurement circuit. | No change in output. |
| Entrained Air | No change in output as only fuel height in the tank or fuel volume is measured in a non-electrical contact manner. The fuel is not a part of the fuel measurement circuit. | No change in output. |
| Contamination | Mildly Effected - Self cleaning due to generous clearances that do not effect system accuracy | Affects potentiometer traces - Accuracy is Slowly Degraded |
| Fuel Motion | No Effect on Sensor. Out of Plane Motion has No Effect. Dense closed cell float utilized dampens fuel motion. | Considerable effect on potentiometer wiper - dithering and Morse coding due to motion in and out of plane of the float arm swing. |
| Safety | No Electronics in the Fuel Tank - No hazard intrinsically safe. | Electronics and electrical contacts in the tank - hazard |
| Damping | Float size is minimized and density is increased which dampens fuel movement | Float dampens fuel movement. |
| Water in Fuel | No Change in Output - No Electrical Contact with the fuel tank contents. | Sender is grossly degraded, by moisture and water induced corrosion products. |
| Compatibility | Mounts in Existing Fuel Quantity Locations | Same |
| Output | Frequency, Voltage, Resistance | Resistance |
| Accuracy | Highest accuracy available for fuel quantity measurement. Exceeds 0.75% - No measurable error or hysteresis in TSO testing. | Poor as it is reliant on the resistive follower size and or the resistance wire or resistive grid size. |
| Float Error | Minimized as float buoyancy does not need to drive a mechanical interface. Smaller and denser floats are utilized in Magnetic Field fuel quantity systems | Float must move wiper against potentiometer reliably - Larger float needed to overcome corrosion |
| Corrosion | No effect on fuel level output | Highly affected, degrades measurement, restricts motion and deposits corrosion products in the fuel. |
| Fuel Oscillation | No Issue - physical and electronic damping | Dithering of output. |
| Complexity | Simple | Simple |
Magnetic Field vs. Ultrasonic
| Characteristic | Magnetic Field | Ultrasonic |
|---|---|---|
| Fuel Quality | No change in output as only fuel height in the tank or fuel volume is measured in a non-electrical contact manner. The fuel is not a part of the fuel measurement circuit. | Change in output as subtle changes in fuel composition change output. |
| Fuel Temperature | No change in output as only fuel height in the tank or fuel volume is measured in a non-electrical contact manner. The fuel is not a part of the fuel measurement circuit. | Change in output as fuel density changes. |
| Entrained Air | No change in output as only fuel height in the tank or fuel volume is measured in a non-electrical contact manner. The fuel is not a part of the fuel measurement circuit. | Change in output as this represents a density change. |
| Contamination | Mildly Effected - Self cleaning due to generous clearances that do not effect system accuracy | Change in output due to contamination on target or transmitter. |
| Fuel Motion | No Effect on Sensor. Out of Plane Motion has No Effect. Dense closed cell float utilized dampens fuel motion. | Considerable effect on output. |
| Safety | No Electronics in the Fuel Tank - No hazard intrinsically safe. | No electronics in the fuel tank. |
| Damping | Float size is minimized and density is increased which dampens fuel movement | Electronic damping only. |
| Water in Fuel | No Change in Output - No Electrical Contact with the fuel tank contents. | Sender is grossly degraded. |
| Compatibility | Mounts in Existing Fuel Quantity Locations | Same |
| Output | Frequency, Voltage, Resistance | Ratiometric Voltage |
| Accuracy | Highest accuracy available for fuel quantity measurement. Exceeds 0.75% - No measurable error or hysteresis in TSO testing. | Good accuracy when conditions are ideal, sloshing fuel, fuel temperature stratification and fuel foaming present accuracy issues. |
| Float Error | Minimized as float buoyancy does not need to drive a mechanical interface. Smaller and denser floats are utilized in Magnetic Field fuel quantity systems | No Issue |
| Corrosion | No effect on fuel level output | No Issue |
| Fuel Oscillation | No Issue - physical and electronic damping | Fuel foam, vapor effect output |
| Complexity | Simple | Complex |
Magnetic Field vs. Reed Switch
| Characteristic | Magnetic Field | Reed Switch |
|---|---|---|
| Fuel Quality | No change in output as only fuel height in the tank or fuel volume is measured in a non-electrical contact manner. The fuel is not a part of the fuel measurement circuit. | No change in output as only fuel height in the tank or fuel volume is measured in a non-electrical contact manner. The fuel is not a part of the fuel measurement circuit. |
| Fuel Temperature | No change in output as only fuel height in the tank or fuel volume is measured in a non-electrical contact manner. The fuel is not a part of the fuel measurement circuit. | No change in output as only fuel height in the tank or fuel volume is measured in a non-electrical contact manner. The fuel is not a part of the fuel measurement circuit. |
| Entrained Air | No change in output as only fuel height in the tank or fuel volume is measured in a non-electrical contact manner. The fuel is not a part of the fuel measurement circuit. | No change in output – Non-Contact |
| Contamination | Mildly Effected - Self cleaning due to generous clearances that do not effect system accuracy | Mildly effected - Self Cleaning |
| Fuel Motion | No Effect on Sensor. Out of Plane Motion has No Effect. Dense closed cell float utilized dampens fuel motion. | Dependent on number and quantity of reed switches, can be dramatic |
| Safety | No Electronics in the Fuel Tank - No hazard intrinsically safe. | No electronics in the fuel tank |
| Damping | Float size is minimized and density is increased which dampens fuel movement | Float dampens fuel movement |
| Water in Fuel | No Change in Output - No Electrical Contact with the fuel tank contents. | No Change in Output - No Electrical Contact with the fuel tank contents. |
| Compatibility | Mounts in Existing Fuel Quantity Locations | Mounts in Existing Fuel Quantity Locations |
| Output | Frequency, Voltage, Resistance | Resistance |
| Accuracy | Highest accuracy available for fuel quantity measurement. Exceeds 0.75% - No measurable error or hysteresis in TSO testing. | Poor Accuracy and is limited by number of reed switches on the circuit card |
| Float Error | Minimized as float buoyancy does not need to drive a mechanical interface. Smaller and denser floats are utilized in Magnetic Field fuel quantity systems | Float Size determines reed switch quantity |
| Corrosion | No effect on fuel level output | No issue |
| Fuel Oscillation | No Issue - physical and electronic damping | Dependent on number and quantity of reed switches, can be dramatic |
| Complexity | Simple | Simple |
