hi, i have MPXH6115AC6U and i want to test shallow water depth, if i enclose this sensor in epoxy and only the tip will be in contact with water, will it work?

[antonvainer]

i want to measure specific gravity of a liquid by testing pressure at 10cm and 20cm in the liquid.

can this be done with MPXH6115AC6U if i expose to water only the tip of the sensor?

[reyes · Accepted solution]

Hi Anton,

We can only warranty that the pressure sensor will work as long as the internal die of the sensor is not in direct contact with the water.

Other media than dry clean air has the potential to dissolve, or be absorbed by the gel and corrupt the die surface or lead to wire-bond breakage. Some types of media will take longer to corrupt the die than others, so a disposable application is possible.

I would like refer you to the application note AN3728: “Media Compatibility for IPS PRT Pressure Sensors” that would be worth to be considered in addition to the provided information.
AN3728: Media Compatibility for IPS PRT Pressure Sensors
http://www.nxp.com/files/sensors/doc/app_note/AN3728.pdf

In this application note at page# 3, you can see that we have tested a couple of media, mainly on parts having media resistant gel, but we cannot give a guarantee about the long term reliability of these devices under these conditions.

We normally recommend that if a customer wants to use the pressure sensor with a different media than “Dry Clean Air”, they must validate the product performance in their application and assume all risk and liability. A determination must be made if this impact is acceptable for the application.

Possible solutions to use our sensors in applications with other media than dry air:
NXP uses two different types of gels in order to isolate the die from the environment:

The Fluorosilicone Gel (Type FE-53) is being used for all our standard type of pressure sensors.

Media Resistant Gel (Sifel) is being used for our pressure sensors that are used e.g. in high temperature environments, mainly in automotive applications.

Now, instead of the MPXH6115AC6U (Fluorosilicone Gel type), I would recommend you to use the MPXHZ6115AC6U which have the same operational characteristics, but it use Media Resistant Gel.

Recommended Lecture: Application note AN1950 “Water Level Monitoring”: http://cache.nxp.com/files/sensors/doc/app_note/AN1950.pdf

I hope this information can be useful.

Have a great day,
Jose

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