Hardware

The POROLUX™ porometers are state state-of-the-art and have the best technical specifications and quality. The products are made in Germany and conform to EU-guidelines and relevant product safety directives and have uniformity in manufacturing (GMP – Good Manufacturing Practice). All come equipped with all necessary hard- and software required for operation. There will be no need to later on add extra pressure sensors and/or flow meters, thus expensive upgrades are avoided. Additional accessories and options are available to give the user access to some advanced porometry options.

ACCURACY OF THE FLOW AND PRESSURE SENSORS

The highest accuracy in pressure and flow available in the market: 0.05 % F.S.

AUTOMATIC SWITCH BETWEEN PRESSURE SENSORS AND FLOW SENSORS

The POROLUX™ porometers have multiple pressure and flow sensors for an optimum performance over the operating range. The switch between pressure and flow sensors during a measurement is automatic depending on the values achieved in order to use the best sensor to optimise the accuracy and resolution at every end (low and high) of the pressure range.

RESOLUTION PRESSURE AND FLOW SENSORS: 24 BIT

Resolution is defined as the ability to discern between differences: a high resolution system resolves small differences while a low resolution one cannot distinguish small differences between two signals.

Speaking from the point of view of an instrument, resolution is understood as the smallest increment or step that can be achieved. In CFP the only two parameters measured are the pressure applied and the gas flow through the sample so in order to determine the resolution of a porometer we need to look at the resolution of the flow and pressure sensors.

A pressure or flow sensor gives an analogue signal that has to be converted into a series of digital values that we will call “steps”. The number of steps depends on how good the converter is (“bit-number”) and it is 2 to the power x, where x is the bit number. For instance, a pressure sensor in the range 0-35 bar that gives a voltage signal between 0-10 V, so 3.5 mbar correspond to a signal of 1 mV. The resolution in voltage is obtained by dividing the full scale of voltage (for example 10 V=10000 mV) by the number of steps. This is transduced into a resolution in pressure by taking the voltage measured in one step and multiplying it by the factor that relates pressure and voltage.

 16 bit24 bit
Number of steps65,53616,777,216
Resolution of the voltage signal0.15 mV/step0.0005 mV/step
Resolution in pressure0.525 mbar/step0.00175 mbar/step

In conclusion, a 24 bit system has much better resolution because it differentiates smaller different analogue signals, which translate into different pressure values. In a 16 bit system different analogue signals are transduced into the same pressure and this leads to a certain error in the calculation of the pore sizes.