Water Activity Meter
Portable water activity meter measuring aw from 0-0.980 with ±0.012 accuracy, featuring LCD display and integrated micro printer for moisture availability analysis in diverse sample types.
Louise Corscadden, PhD
Neuroscience · ConductScience
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The Water Activity Meter provides precise measurement of water activity (aw) in samples across a range of 0 to 0.980, utilizing single-point calibration for accurate determination of moisture availability in materials. The instrument operates across environmental conditions from 0-50°C and 0-95% relative humidity, making it suitable for diverse laboratory and field applications where moisture content analysis is critical for product stability, shelf life determination, and quality control protocols.
Featuring an LCD display and integrated micro printer, the system delivers measurement results with ±0.012 accuracy at 23°C±5°C, completing analyses within 5-40 minutes depending on sample characteristics. The temperature coefficient of ≤0.0005/°C ensures measurement stability across the operating temperature range, while activity repeatability of ≤0.01 provides consistent results for routine testing applications.
How It Works
Water activity measurement is based on the equilibrium relative humidity principle, where the water activity of a sample equals the equilibrium relative humidity of the air above the sample divided by 100. The instrument utilizes a calibrated humidity sensor to measure the equilibrium relative humidity in a sealed measurement chamber containing the sample.
The sample is placed in the measurement chamber where water molecules establish vapor pressure equilibrium between the sample surface and the headspace air. The humidity sensor detects this equilibrium state, converting the relative humidity reading to water activity values. Temperature is simultaneously measured to ensure accurate compensation, as water activity is temperature-dependent with the built-in temperature coefficient correction of ≤0.0005/°C.
Single-point calibration using reference standards ensures measurement accuracy across the 0-0.980 aw range. The measurement process requires 5-40 minutes depending on sample type and moisture content, allowing sufficient time for complete equilibrium establishment between the sample and measurement chamber atmosphere.
Features & Benefits
Automation Level
- semi-automated
Working Temp.
- 0~50°C
Working Humidity
- 0~95%RH
Measuring Range: Temperature
- 0~50°C
Measuring Range: Water Activity
- 0~0.980
Measurement Accuracy: Temperature
- ±0.5°C
±0.015(@25°C)
- ±0.012(@23°C±5°C)
Measurement Time
- 5~40min
Measurement Points
- 1
Temperature Coefficient
- ≤0.0005/°C
Activity Repeatability
- ≤0.01
Correction Mode
- Single-point calibration
Interface
Standard Accessories
- Micro printer, one sensor
Brand
- ConductScience
Research Domain
- Analytical Chemistry
- Environmental Monitoring
- Food Science
- Industrial Hygiene
- Materials Science
- Microbiology
- Pharmaceutical QC
Display Type
- LCD display
Weight
- 29.98 kg
Dimensions
- L: 42.0 mm
- W: 43.6 mm
- H: 38.0 mm
| Feature | This Product | Typical Alternative | Advantage |
|---|---|---|---|
| Water Activity Range | 0-0.980 aw | Entry-level models often limited to 0.1-0.9 aw | Extended lower range capability allows analysis of very dry materials and ultra-low moisture products. |
| Measurement Accuracy | ±0.012 at 23°C±5°C | Basic units typically offer ±0.02-0.03 accuracy | Higher precision supports critical quality control applications where small water activity differences are significant. |
| Temperature Compensation | ≤0.0005/°C coefficient | Lower-cost models may lack automatic temperature compensation | Eliminates need for constant temperature control and reduces measurement uncertainty across varying conditions. |
| Documentation System | Integrated micro printer | Many portable units require external printers or manual recording | Immediate hard copy generation reduces transcription errors and supports audit trail requirements. |
| Measurement Time | 5-40 minutes | Varies by model | Optimized equilibration time balances measurement speed with accuracy for diverse sample types. |
| Operating Environment | 0-50°C, 0-95% RH | Limited environmental range in basic models | Extended operating conditions support field use and non-climate-controlled environments. |
This water activity meter offers precision measurement capabilities with integrated documentation and robust environmental tolerance. The combination of extended measurement range, high accuracy, and built-in printing provides comprehensive functionality for quality control and research applications requiring reliable moisture availability assessment.
Practical Tips
Verify calibration using multiple reference standards spanning your typical measurement range rather than relying solely on single-point calibration.
Why: Multi-point verification ensures linearity across your specific application range and identifies potential drift issues.
Clean the measurement chamber and sensor regularly using appropriate solvents to remove sample residues that could affect equilibration.
Why: Contamination buildup can alter chamber vapor dynamics and lead to measurement drift or extended equilibration times.
Allow samples to reach thermal equilibrium with the measurement chamber temperature before initiating measurements.
Why: Temperature gradients between sample and chamber can extend equilibration time and introduce measurement uncertainty.
Use consistent sample preparation techniques including grinding, particle size, and sample depth to ensure reproducible results.
Why: Sample physical characteristics affect surface area and vapor release, directly impacting equilibration kinetics and measurement accuracy.
Record ambient temperature and humidity conditions along with water activity measurements for quality documentation.
Why: Environmental conditions can influence measurement performance and are valuable for troubleshooting unexpected results or method validation.
If equilibration time exceeds expected ranges, check for chamber leaks, sensor contamination, or sample preparation issues.
Why: Extended equilibration often indicates compromised chamber integrity or non-representative sampling affecting vapor pressure dynamics.
Ensure proper ventilation when measuring samples containing volatile compounds or potential contaminants.
Why: Sample vapors may contain hazardous substances that require appropriate handling protocols to protect operator health and prevent cross-contamination.
Setup Guide
What’s in the Box
- Water Activity Meter main unit
- Humidity sensor
- Micro printer
- Power adapter (typical)
- Sample cups and lids (typical)
- Calibration standards (typical)
- User manual and quick start guide (typical)
- Printer paper rolls (typical)
Warranty
ConductScience provides standard 1-year manufacturer warranty covering defects in materials and workmanship. Technical support includes calibration guidance, troubleshooting assistance, and method development consultation for specialized applications.
Compliance
What sample size is required for accurate water activity measurement?
Consult product datasheet for specific sample volume requirements. Sample size should provide sufficient surface area for vapor equilibrium while fitting within the measurement chamber dimensions.
How frequently should calibration be performed?
Single-point calibration should be verified daily for routine use or before critical measurements. Full calibration verification using multiple reference standards is recommended weekly or monthly depending on measurement frequency and accuracy requirements.
Can the instrument measure water activity in liquid samples?
The 0-0.980 measurement range excludes pure liquids (aw = 1.0). The instrument is designed for materials with reduced water activity such as foods, pharmaceuticals, and materials with bound or restricted water availability.
What environmental conditions affect measurement accuracy?
Ambient temperature fluctuations and high humidity can impact equilibration time and accuracy. Maintain stable laboratory conditions within the 0-50°C operating range and below 95% relative humidity for optimal performance.
How does temperature affect water activity measurements?
Water activity is temperature-dependent, with the instrument providing automatic temperature compensation using a ≤0.0005/°C coefficient. For critical applications, consider measuring at standardized temperatures to minimize temperature-related variations.
What data output formats are available?
The integrated micro printer provides immediate hard copy results. Consult product datasheet for digital output capabilities and data logging options.
How does this compare to gravimetric moisture analysis methods?
Water activity measurement determines moisture availability rather than total moisture content, providing different but complementary information about water's influence on chemical reactions, microbial growth, and material stability.
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