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Valmet IQ Porosity Measurement

The accurate machine direction trend and high-resolution porosity profiles measured by Valmet IQ Porosity Measurement (IQ Porosity) provide a solid foundation for producing paper and board with uniform porosity.

Valmet IQ Porosity Measurements

Improved porosity influences positively not only the sheet strength and coating pickup, but also sheet surface properties. Air permeability is also one of the key variables for sack, filter, cigarette, and other special papers. IQ Porosity gives an instant response to porosity changes caused by refining, wet end, press and calender operations and as a result on-spec quality can be reached faster and start-up waste is reduced.


IQ Porosity is a single-sided scanning or fixed point measurement. The online measurement method correlation to Valmet Paper Lab and other laboratory measurements is excellent.

Advanced third generation porosity measurement technology is based on air pressure measurement. Thanks to the new method, there is no need for vulnerable air flow measurement or measurement vacuum control. The new measurement technology provides excellent porosity measurement performance even in positions and applications where it has not been possible to use online porosity gauges before.

IQ Porosity is installed in a scanner or in a fixed point platform as any other Valmet IQ sensor. The sensor is equipped with a sheet stabilization plate using the Coanda effect which gently touches the sheet. This ensures that the air is not leaked between the sheet and the sensor head, but all the measured air is coming through the sheet. The sensor head vertical position can be adjusted by a stepping motor so that sheet fluttering does not affect the measurement readings. IQ Porosity is equipped also with an air blast function, which removes accumulated dust from pipelines and sensor surfaces. The cleaning can take place during the traversing or in the off-sheet position.


  • Accurate and high-resolution porosity profiles for precise control of porosity in machine and cross directions
  • Measurement gives an instant response to porosity changes caused by process operation adjustments. As a result, on-spec paper quality can be reached faster and start-up waste is reduced
  • Energy and furnish costs can be minimized by precise control of porosity
  • Reduction in rejects due porosity variation, roll quality and related issues
  • Improved porosity affects positively also for printability and paper surface properties
Structural properties measurements
Valmet IQ Formation Measurement

Valmet IQ Formation Measurement

The IQ Formation Measurement gives an instant response to formation changes caused by process adjustments.