We need to talk to ANYONE who has experience using the MXPH6400 series of pressure sensors in wet (fresh and sea water) environments. What sort of sensor life can be expected? Is there a way that works to protect the internal gel by adding a layer of supersoft RTV, or silicon grease???
ANY help and guidance would be really appreciated?
Kelly Borsum, DASCOR, Inc. 619-794-7788 email@example.com
I hope everything is well with you.
I am afraid that I do not have any experience using the MPXH6400 device in wet environments but I would like to add some comments/suggestions:
- Note that for all NXP standard pressure sensor products, any environment other than dry air, will have some impact on the reliability and lifetime of the product. NXP’s silicon pressure sensors are NOT compatible with oil, gas, petrol and water or water vapors, or chemicals.
- After some working hours, maybe days the device would fail because of the use of water.
- Usually in a water measurement application, a head tube is used. This is simply a piece of tubing between the sensor and the container in which the water level or pressure needs to be measured. Air is trapped in the tube and this isolates the sensor from the liquid water.
Please review the application note below for further information:
- Have you considered protecting the sensor against entering humidity or condense water by using proper silicon oil?
Protecting pressure sensors with a silicon grease is definitely the best way to use our products in harsh media. We don't have so much experience in how to implement this solution 'industrially'. The grease fill is done under vacuum to avoid air bubbles. Usually, an offset calibration is necessary because the grease brings some mechanical stress that may shift the offset value. This solution was tested and seems conclusive.
- Have you considered using a device with Media Resistant gel?
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. The Media Resistant Gel (Sifel) is being used for our pressure sensors that are used e.g. in high temperature environments, mainly in automotive applications. All pressure sensors with the designator MPXAZ, MPXVZ, MPXHZ are those using Media Resistant Gel (Sifel). This series of devices uses our automotive grade gel which is much more resistant to harsh media. The customer however must perform the validation in their application, but the product will be more robust then the existing standard pressure sensors.
In any case, you must validate the product performance in your application and assume all risk and liability.
I hope that this information will be useful for you.