VSA vapour sorption analyser

automated soil water characteristic curves


feature summary
  • Fast, expansive soil characterization
  • Automatic static and dynamic soil water characteristic curves
  • Measure soil-specific surface area
  • Generates curves with up to 200 data points for both adsorption and desorption
  • Works in the dry soil range (-10 to -475 MPa)
  • Set up a test in five minutes
  • Steady sorption dynamics with static water potential feature


simple instrument—advanced scientific breakthroughs

If you want to understand complex soil issues like clay behaviour, specific surface area, shrink-swell capacity, or cation exchange capacity, the VAPOR SORPTION ANALYZER (VSA) is your simplest, most accurate option. It automates the entire process of soil water characteristic curve construction in the dry region (-10 to -475 MPa) by accurately measuring simultaneously, at regular intervals, the water potential and the moisture content of a sample. No other instrument gives this much detail about soil in the dry range.

delve deeper into your dry soil analysis

The VSA enables you to make detailed measurements that no other instrument can. This means you can study the soil at a particle level, examining its chemical makeup and how the layers of soil imbibe water as it gets wetter or lose water as it
gets drier. For the first time ever, it’s possible to see hysteresis in dry soils because the VSA analyzes both wetting and drying curves. This is critical information because the area between those curves is indicative of water intrusion into clay layers at the molecular level.

The VSA generates both Dynamic Dew Point Isotherm (DDI) and Dynamic Vapor Sorption (DVS) soil water characteristic curves. How? It continuously wets the sample and stops periodically to measure how heavy it is (DDI), or it keeps the
sample at a constant humidity, recording how long it takes the sample to come to equilibrium (DVS). In just 24 to 48 hours, the VSA generates curves with up to 200 data points (water potential vs. water content) for both adsorption and

With so much information at your fingertips, insights are now officially faster and more convenient.

set up a test, and walk away

With the VSA, it takes about five minutes to set up a test. Simply tell the instrument the water potential range and times you’d like to use, put the sample into the instrument, and move on to other tasks. The data from your test are automatically recorded and sent to your computer. Powerful automation adds up to powerful time savings.

explore new frontiers in science

What’s the next great scientific advancement that’s going to be made with this instrument? Only you can say. The VSA’s incredibly detailed soil water characteristic curves let you research complex soil behaviours no one’s yet explored. Sophisticated information and powerful efficiency make it easier than ever to draw accurate conclusions about your soil’s behaviour, its expansibility, its makeup, and its performance as an engineering material.




feature specification
measurement specifications
Water Potential Range: -10 to -475 MPa Accuracy: ±1 MPa, or ± 1%
External Gas Not needed. If external gas is used, no more than 7 PSI
Isotherm Methods Dynamic Dew Point Isotherm (DDI) & static DVS (Dynamic Vapor Sorption)
Temperature Control Range: 15 to 60 °C (sample chamber temperature; sample temperature is measured separately and may vary)
communication specifications
Computer Interface USB
physical specifications
Dimensions Length: 38.1 cm (15 in) Width: 25.4 cm (10 in) Height: 30.5 cm (12 in)
Sample Cup Volume 10 cc
Sample Weight Range 500-5000 mg
Weight Accuracy ± 0.1 mg
Universal Power 110 – 220 V AC 50/60 Hz
Water Reservoir 20 mL
Operating Temperature Range 15.00 – 40.00 °C
Weight 12.7 kg (28 lbs.)

manual & docs

related products