More and More companies who are traders , know how to choose the type of defoamers in papermaking process. However , how to evaluate defoamer’s performance in papermaking process, they just do some lab in simple test by eye observing the foam. It works but is not comprehensive.

In order to evaluate comprehensively,  you need to know the air content measure, which is mainly used to detect the air content in low concentration liquid, expressed in %

Principle:

The Boyle gas equation based gas (P1xV1=P2xV2) is used to determine the gas content in a liquid. During the measurement process, an atmospheric pressure is applied to the test sample in the EGT by turning a knob. The pressure is indicated by a closed bubble reserved in the pressure indicator. When the foaming volume is reduced by half, the pressure applied, at this time, is just one atmospheric pressure, that is, the volume of all gas in the sample is reduced by half. Because the volume of the sample chamber is known and is constant, the percentage coefficient of air represented by each turn of the knob can be calculated.

When an atmospheric pressure is applied, please record the total number of turns of the knob, subtract the correction parameter 0.75 (note: each instrument is different, need to test with water first), multiply by the air percentage coefficient mentioned above, and then you can get the air percent content.

The formula for measuring air content is:（N-0.75)*0.629

It’s not enough for learning the air content measurement, and it’s fundamental knowledge about relationship between air bubble content in slurry and paper quality and papermaking.

The factors are dehydration time, air permeability, ration, evenness , tensile strength and wet strength. Please contact Rickman expert for more information about that.