Are there any Freescale Pressure sensor for negative pressure ?

[luizsilva]

Hello Guy,

I`m looking for any Freescale Pressure sensor which is able to measure negative pressures.

I want to use this type of sensor in a medical equipament, a autoclave.

If  you have sugestions, I'll apreciate it.

Thank you soo much,

Luiz Silva

[Joshevelle]

Hello Luiz Silva

Thank you for writing and for using our community. Unfortunately you didn’t mention a pressure range or temperature, so I cannot recommend a device for your application; please provide more information so I can do a quick search.

Most of our pressure sensors are compensated for a temperature range from 0 to 85°C and they’re designed to measure pressure in one direction; we have some low-range bi-directional pressure sensors (MPXV70XX family). It is possible to measure either a positive pressure OR a negative pressure, but not both. For example, the sensor can be designed to accept a "positive" pressure on the P1 port, providing that P1 is greater or equal to P2 while staying within the sensors specified pressure range. Or, the sensor can measure "negative" pressure (vacuum) by applying vacuum to P2, again while P1 is greater or equal to P2 and staying within the sensors specified range. Freescale specifies, and qualifies its pressure sensors applying pressure in one direction only. In any case pressure one should be greater than pressure in port 2 (P1>P2), P1 side is the pressure side; P2 side is the vacuum side.

Hope it helps!

Josh

[luizsilva]

Joshevelle,

I want to measure: from -0,81 KGF/cm2 to +5KGF/cm2, I mean, from -80kPa to +500KPa.

Do you sugest some part number ?

Thank you,

Luiz Silva.

[Joshevelle · Accepted solution]

Hello Luiz Silva,

Unfortunately we do not have a bi-directional pressure sensor that can support your application pressure range.  As mentioned in my last comment, our pressure sensors are designed to measure pressure in a single direction (P1>P2), if P2>P1 unexpected results can damage the reliability of the device.

The widest bi-directional range that our pressure sensors can support goes from -25kPa to +25kP, MPXV7025DP.

We’re sorry for the inconveniences.

Josh

[luizsilva]

Thank you Joshevelle.

My last question:

I want to use one of this Mounting Techniques, described in the PDF below, for MPX5999.

But we have available only the UNIBODY PACKAGE.

Do you knom from whiom I can buy the others packages ? From freeecale ?

Thank you.

[Joshevelle]

Hello Luiz Silva,

I couldn’t see the PDF you mentioned, I assume you’re talking about AN936:

http://cache.freescale.com/files/sensors/doc/app_note/AN936.pdf

You can find vendors information in page 5 of the document; you could also send that page (page 5) to a lathe man, so they can build the connector shown there (Figure 8) which is designed for unibody packages.

The MPX999 is a pressure sensor with a pressure range from 0 to 1,000kPa and is capable of handling pressures up to 4,000kPa (maximum common mode pressure). Unfortunately no other Freescale package would be able to handle such pressure level, that’s why the device is only available in unibody package.

Hope it helps.

Regards,

Josh