Pressure sensors enable customized solutions for almost any task in pressure transmitters – absolutely precise and reliable. We have to consider installation conditions (flush, non-flush), application requirements (hygienic, industrial) and media properties.


Types of pressure

Absolute:

Relative:

Compound:

Differential:

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Pressure sensor technology


Suitability for gas applications

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Pressure in sterilization processes

Hot steam is used to sterilize devices and equipment. Small elements, such as sensors (PBMH autoclavable), can be sterilized in a suitable chamber (autoclave). In larger installations, hot steam is fed through the system, which is described as “Sterilization in place” (SIP). Accordingly, a sensor must be designed to be robust, although the signal is generally not transmitted during the sterilization process. It must survive the prevailing temperature and pressure for the relevant time span (e.g., 134 °C at more than 3 bar for 30 min). In physical terms, pressure and temperature are coupled directly with each other, which is shown in the saturated steam curve.

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Pressure of saturated steam with respect to temperature

Baumer PBMx and PFMx pressure sensors are ideal for controlling the sterilization process. They provide accurate values even in the event of fast changes in temperature, and thus control the process reliably by monitoring pressure, which leads to the corresponding temperature.

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Definition of the pressure ranges

Explanation of terminology and relationships

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  • Precision: This describes the possible deviation of a single measurement from the average of many measurements and can be interpreted as a dispersion circle. High precision: small dispersion circle, low precision: large dispersion circle.
  • Accuracy: This describes the distance (offset) of the average value of many measurements from the true value. High accuracy: small offset, low accuracy: large offset.
  • Standard error of measurement: This information is obtained through the best fit straight line, BFSL, and describes precision (dispersion circle).
  • Maximum error of measurement: This contains the standard error of measurement and the offset of a sensor.

Temperature dependence

The application may deviate from the reference temperature (e.g. 20 °C), so that the standard or the maximum error of measurement must be regarded in a differentiated manner.

Temperature dependence of the maximum error of measurement
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In many cases, a temperature-stable sensor with lower initial accuracy is to be preferred to a more unstable sensor with higher initial accuracy if the operating temperature deviates from the reference temperature (e.g. 20 °C).

Error indication

Baumer specifies the “maximum error indication”, i. e. statistically, 99.7% of the sensors comply with the specification. Some competitors enter the “typical error indication”, in which 32% of the products do not comply with the specification.

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Unit Conversions

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