Automated Particle Size Analysis


What’s new with PARIO Plus?

PARIO Plus lowers the estimated error from +/- 3% to an incredible +/- 0.5%. And we’ve decreased the measurement time from 8 h to 2.5 h, so you can make even more measurements in less time.

Upgrade your PARIO Classic with the purchase of a new cylinder. To upgrade, contact sales.

New technology—new possibilities

Conventional soil particle size analysis traditionally had only two options—the extremely archaic option or the extremely expensive option. The older hydrometer (or pipette) method is a long, painstaking, manual process requiring many measurements at precise intervals for up to 24 hours, making it prone to error. The ultra-expensive laser method has accuracy issues because flat soil particles like clay can confound the measurement. Both methods can lead to hours of wasted time and effort.

That’s why we developed a revolutionary new way to reduce the time and effort needed for soil particle size analysis.

Particle size analysis, automated

PARIO calculates the particle size distribution by Stokes’ law, with a range spanning from 63 μm to 2 μm, finally making it easy to obtain a complete particle size distribution curve, instead of just a few measurements at discrete time points.

It allows for unattended, automated operation (with the exception of opening the valve after completion). Just set it up and come back later to a finished measurement with all the data you need.

New method reduces error—and effort

PARIO adopts the same sample prep your lab already uses, so it fits perfectly into your existing workflow. It reduces errors by replacing and automating the lengthy “hydrometer” portion of the process using the new, more accurate “Extended Integral Suspension Pressure Method” (ISP+). This method does not require the insertion of a hydrometer or sampling of suspension volume with a pipette, which disturbs the sedimentation process. Being automatic, it also avoids manual reading or calculation errors. This results in an overall error rate of an incredible 0.5%—lower than any conventional particle size analysis method.

PARIO automatically measures at an interval of ten seconds and continuously records the change of suspension pressure as well as the temperature. This results in highly accurate and continuous particle size distribution curves. The data are automatically evaluated by our new data processing algorithm called the ISP+ method.

The PARIO measuring method is based on Stokes’ law. That means there is no need for soil-specific corrections with transfer functions as required for almost any other automated measurement method, such as laser diffraction or image analysis.

Spend more time on what matters

To save you even more time, PARIO comes with an easy-to-use, all-in-one software solution for automated data inquiry, visualization, evaluation and export. Plus, PARIO, as part of the LABROS system, can be combined with the HYPROP, KSAT, or WP4C to completely characterize the physical and hydraulic properties in soil.

All of this serves one goal—to reduce the operating time you spend for particle size analysis, while at the same time improving accuracy. Skip hours of tedious manual measurements, and focus on your research.

The new PARIO soil texture analyzer. Complete particle size distribution curves. Not one particle of wasted time.

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  • Get complete particle size distribution curves
  • Calculation of particle size distribution by Stokes’s law
  • Autonomous operation after measurement start (with the exception of opening the valve at measurement end)
  • Lower measurement duration of 2.5h
  • Estimated error: an incredible +/- 0.5%
  • Quasi-continuous resolution of particle size distribution
  • No physical disturbance of suspension during measurement
  • Avoidance of manual reading errors
  • Avoidance of manual calculation errors
  • Temperature dependence automatically integrated in the calculation of particle size distribution
  • Direct measurement of clay content
  • PARIO Plus improvements mean external data errors are less problematic


View GSA details


Particle size

Range: 2-63 μm

Approximate error in mass fraction detection

PARIO Classic: ±3.0%
PARIO Plus: ±0.5%

Pressure measurement

Accuracy: ±1.0 Pa
Resolution: ±0.1 Pa

Typical particle mass

25−50 g per 1-L suspension

Typical duration of measurement

PARIO Classic: 8.0 h
PARIO Plus: 2.5 h

Measurement interval

10 s

Estimation of clay content

Derived from integrated particle mass in effluent

Estimation of sand fraction

Sand fraction estimated by sieve data


Power requirements

USB 5 V/100 mA

Computer compatibility

Microsoft Windows 10


Glass cylinder

Height: 450.0 mm (17.7 in)
  Inner: 59.0 mm (2.3 in)
  Outer: 67.5 mm (2.7 in)
Volume: 1,000 cm3 (61.0 in3)
Material: Borosilicate glass 3.3

PARIO device

Height: 293.0 mm (9.1 in)
Diameter: 80.0 mm (3.2 in)
Material: Polyoxymethylene plastic (POM) and stainless steel

Volume of suspension

1,000 mL

Operating temperature

Minimum: 15 °C
Typical: 20 °C
Maximum: 35 °C

Maximum tolerable temperature change during measurement

±1.5 °C

Required external measurements

PARIO Classic: Content of organic matter (if OC is destroyed)
Sand fractions (from wet sieving)
Mass of dispersion salt in total suspension volume

PARIO Plus: Mass of dry matter in discharged subsample
Sand fractions (from wet sieving)
Mass of dispersion salt in total suspension volume

Cable type

USB 2.0; 500 mA for receiving port


Manufactured under ISO 9001:2015
EM ISO/IEC 17050:2010 (CE Mark)

California requires the following notice:

⚠️ WARNING: This product may contain chemicals including ethylene glycol, lead, nickel, styrene and cadmium, which are known to the State of California to cause cancer, birth defects or other reproductive harm. For more information, go to www.P65Warnings.ca.gov



Have a question or problem? Our support team can help.

We manufacture, test, calibrate, and repair every instrument in-house. Our scientists and technicians use the instruments every day in our product testing lab. No matter what your question is, we have someone who can help you answer it.

Phone US: +1 509-332-5600
Phone Europe: +49 89 12 66 52 0


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