What are the setbacks of an oil-filled sensor vs. non-oil filled?

In the pressure sensing industry there are many different sensor technologies, but all sensors can be broken down into two classifications; oil-filled, non-oil filled. An oil-filled sensor refers to a sensor that uses oil as a transfer medium between a diaphragm and the sensing element. Oil-filled sensors appeal to many manufacturing applications due to its material compatibility, low cost, and ease of implementation. Although these sensors are becoming a standard, there are several drawbacks to selecting an oil-filled sensor over a non-oil filled sensor.

1. Difficult to Mount

   • As you rotate an oil-filled sensor for mounting, gravity will affect the sensor. The oil will shift based on the direction of the gravitational pull, shifting the transducers zero output reading. A non-oil filled sensor will have a zero reading that is more stable.

2. High Cost of Failure

   • If the sensing diaphragm ruptures due to overpressure or manufacturing defect, oil can leak into the application and contaminate the system. If the oil gets into the system, it can damage the critical components costing millions of dollars depending on the application (i.e. fuel cells). Unfortunately there is no fix for many systems once they are contaminated by oil.

3. False Readings

   • In high temperature environments, the oil in the sensor is susceptible to expansion. If the oil expands due to the high temperature, the sensor provides a false pressure reading which can go undetected and ruin an experiment or piece of equipment due to an unwanted reaction to the analog output.

Similar Applications: Fuel Cell OEMs, CNG & LNG Applications, Hydrogen Production System, Water & Wastewater, Natural Gas Distribution

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