AS ONE 4-2453-02 MD-AW2 Water activity measuring device with simple memory (20 items) (0- 1.00Aw, +/-0.03Aw (0 - 0.9Aw), +/-0.04Aw (other than 0 - 0.9Aw))

1. What is the MD-AW2 and what does it measure?

The MD-AW2 is a handheld water activity meter designed for quick on-site determination of a sample’s Aw (water activity). It calculates the ratio of the vapor pressure of water in your test sample to that of pure water at the same temperature, delivering a numerical Aw value from 0 to 1.00.

2. What is water activity (Aw)?

Water activity (Aw) is the ratio of the partial vapor pressure of water in a material to the vapor pressure of pure water under identical conditions. It indicates how much “free” water is available for microbial growth, chemical reactions, and physical changes in foods, pharmaceuticals, cosmetics, and many other products.

3. How does the MD-AW2 measure Aw?

The device uses a capacitance-type humidity sensor inside a sealed sample chamber. Once the sample cup is in place and the chamber closed, the sensor measures the equilibrium humidity and converts it to an Aw reading via embedded algorithms.

4. What are its range, resolution, and accuracy?

Range: 0 to 1.00 Aw

Resolution: 0.01 Aw

Accuracy: ±0.03 Aw from 0 to 0.9 Aw; ±0.04 Aw outside the 0–0.9 Aw range

These specifications ensure reliable control of moisture-sensitive processes and shelf-life predictions.

5. How long does each measurement take?

A typical measurement cycle takes about five minutes from the moment you press the “Measure” button until the Aw value stabilizes on the LCD display.

6. How many results can the MD-AW2 store?

It holds up to 20 readings in its internal memory, enabling quick recall and comparison of recent samples without manual note-taking.

7. What accessories come with the MD-AW2?

100 polystyrene sample cups (⌀ 35 × 10 mm)

3 chemical filters to protect the sensor

1 m USB cable (note: data export via USB is only supported on the MD-AW3 model)

2 AA batteries

These accessories let you begin measurements immediately and guard sensor longevity.

8. What are sensor filters for, and how often should I replace them?

Filters sit between your sample and the sensor to block volatile chemicals that can degrade the sensor’s performance.

If you perform ≤ 10 measurements per week, replace filters every 6–12 months.

For > 10 measurements per week, replace every 3–6 months.

For continuous (24/7) use, change filters every 2 months.

Neglecting filter changes may lead to sensor failure, which is not covered by warranty.

9. What is a PM (Preventive Maintenance), and why is it important?

A PM is an annual service that includes:

Full diagnostics and calibration checks

Replacement of pre-filters

Internal cleaning and sterilization

Performance certification

This “tune-up” prevents wear-related issues, maintains measurement accuracy, and extends your instrument’s lifespan.

10. How do I operate the MD-AW2?

Install two AA batteries in the compartment.

Place a filled sample cup on the holder inside the chamber.

Close the lid and press “Measure.”

Wait ~5 minutes for the Aw reading to stabilize on the LCD.

Save the result or manually record it, then remove the cup and clean for reuse.

11. Are there samples the MD-AW2 should not measure?

Do not use it for high-sugar syrups, alcoholic or highly acidic samples (e.g., vinegar), as these can damage the sensor and yield invalid readings.

12. What are common applications?

Food industry: shelf-life and storage condition validation

Pharmaceutical and cosmetics: moisture control in raw materials and finished products

Agriculture: seed and grain moisture assessment prior to long-term storage

Quality control: ensuring texture, taste, and microbial safety of hygroscopic products

Monitoring Aw helps optimize product quality and prevent spoilage or caking