MPX2102DP Saltwater compatibility

[eduardopantaleo]

Please, I would like to know chemical compatibility of MPX2102DP (Differential Pressure Sensor) for measuring sea water pressure between 14°C and 20°C at max 10 mts water column (aprox. 14 PSI). Since a gel is present between ambient  and silicon membrane. I would like to know if it´s necessary or not, to include another interface liquid or gel in order to prevent damage to the sensor. Thanks

[darioarias]

Hello Eduardo,

There is no special testing of our sensors using sea water, however for standard pressure sensor products, any environment other than dry and clean air, will have some impact on the reliability and lifetime of the product. In general, our pressure sensors were designed and are warranted for use under this conditions. However, we offer an application note (AN3728) that mentions the media compatibility for our pressure sensors.

In the application where the device is exposed to a humid environment, the device is located at the top of a measurement tube - so water level is indirectly measured through the water pushing a trapped air column up to the sensor. As you can see in the following application notes, the sensor does not have a direct contact with water, but is separated by the air column.

AN1950: Water Level Monitoring

http://www.freescale.com/files/sensors/doc/app_note/AN1950.pdf

AN1516: Liquid Level Control Using a Pressure Sensor

http://www.freescale.com/files/sensors/doc/app_note/AN1516.pdf

We have also an application note about media compatibility:                                                       

AN3728: Media Compatibility for IPS PRT Pressure Sensors

http://www.freescale.com/files/sensors/doc/app_note/AN3728.pdf

Regards,

Darío

[eduardopantaleo]

Hello Dario:

Thanks for your very useful help. Just for being sure of what is recommended in AN3728: When you configure the measuring device as in "Figure 2. Media Separated by a Column of Clean Dry Air". The port of MPX 2102DP

connected to the water column tube, must be the "Vaccum side", (the one that doesn´t have gel or silicone). Voltage readings will be reversed too: High output = Low liquid level, Low output, high liquid level. Thanks in advance, I wait for your kind answer.

Regards,

Eduardo Pantaleon

[darioarias]

Hi Eduardo,

Since the MPX2102DP is a differential pressure sensor you only need to make sure the condition P1 > P2 remains true at all times, if you need to measure pressure with the vacuum as a reference I 'd recommend to use an absolute pressure sensor instead or a Gauge pressure sensor if the reference is the ambient. You are correct about the voltage readings, they will be reversed as you mentioned.

Regards,

Darío