1. Introduction
The Water Activity Meter WA-160A is a portable device designed to measure the amount of free water in food products. Water activity is a critical factor influencing food stability, microbial growth, and chemical, enzymatic, and physical changes that affect food quality. This meter is essential for assessing the dryness endurance of microorganisms and for selecting appropriate packaging and storage methods, thereby extending the shelf life of various foods, grains, fruits, and vegetables.
The WA-160A is compact, lightweight (approximately 100 grams), and offers a precision of ±0.03 aw, making it convenient for water activity measurements anytime and anywhere.
2. Product Features
- Integrated sensors and readings for streamlined operation.
- Easy-to-read 6-bit backlight LCD digital display showing water activity (3-bit) and temperature (3-bit) simultaneously.
- Features automatic shutdown, manual shutdown function, and undervoltage alarm indication.
- Supports USB data output for connection to a PC.
- Offers Bluetooth data output as an optional feature.
3. Specifications
| Parameter | Value |
|---|---|
| Display | 6 bit backlight LCD digital display, 3 bit humidity aw, 3 bit temperature display |
| Range | 0~1.0aw |
| Resolution | ±0.01aw |
| Accuracy | ±0.03aw |
| Sensor | Non conductive humidity sensor |
| Sampling Time | Max. 10 minutes (Record the response value of the water activity meter every 5 minutes; when the difference between two adjacent response values is < 0.01Aw, that is the measured value.) |
| Operating Temperature | 0-50 ℃ (32-122℉) |
| Operating Humidity | Below 95% RH |
| Power Supply | 2x1.5V AAA Size (UM-4) Battery |
| Weight | 100g (Not including Batteries) |
| Dimensions | 135mm x 70mm x 44mm |
| Certification | CE |
| DIY Supplies | Electrical |
| Backlight | Yes |
4. Setup
4.1 Battery Installation
- When the battery symbol appears on the display, it indicates that battery replacement is necessary.
- Slide the battery cover away from the instrument and remove the old batteries.
- Install two 1.5V AAA (UM-4) batteries correctly into the case, observing polarity.
- If the gauge will not be used for an extended period, remove the batteries to prevent leakage.
5. Operating Instructions
Follow these steps to accurately measure water activity:
- Take out the instrument from its packaging.
- Open the instrument's measuring room by removing the vessel dish and container lid.
- Place your test sample into the container dish. Ensure the sample is evenly distributed. Note: Do not close the sample vessel's lid at this stage.
- Put the container dish with the sample into the bottom box of the measuring chamber.
- Press the Power key to turn on the instrument. The gauge will enter auto mode.
- Carefully combine the measuring chamber with the sensor. Ensure there is a proper seal (anastomosis) between the two parts. Once combined, the measurement begins.
- Allow approximately 5 minutes for the reading to stabilize. For samples with water activity greater than 0.8 or less than 0.3, the measurement time may extend up to 20 minutes. For water activity greater than 0.95 or less than 0.1, the measurement time can exceed 1 hour, as the moisture and air in the measurement room need sufficient time to mix. The instrument will emit a horn sound every five minutes during longer measurements.
- Once the reading is stable, the water activity value will be displayed.
- After testing, press and hold the Power key for about 3 seconds to turn off the gauge. Clean the sample plate for next use.
6. Reading Correction
If you need to correct the reading value, follow these steps:
- Press and hold the Power Key for approximately 7 seconds. Release the key when 'Cor' appears on the display. A decimal number with two places, representing the correction value, will be shown.
- Open the battery cover on the back. Below the battery slot, you will find two small holes. Use a small hard bar (e.g., a screwdriver) to gently touch the key inside these holes. Touching the right hole increases the correction value, while touching the left hole decreases it. Each touch changes the correction value by 0.01. The correction value can be set within the range of -0.14 to 0.14.
- After completing the adjustment, press the Power Key to exit the correction mode.
7. Connecting to a Computer
To connect your WA-160A meter to a PC for data output, follow these instructions:
- Install the provided USB software on your PC. During the installation process, always click the "continue" button.
- Connect your gauge to your PC using the optional USB cable.
- Switch on your gauge and ensure the Reading Screen is displayed.
- Start the installed software and follow the instructions provided within the software (e.g., Demo.EXE) to access and manage data.
8. Maintenance
- Always clean the sample plate thoroughly after each use to prevent cross-contamination and ensure accurate readings.
- Store the instrument in a dry, cool place, away from direct sunlight and extreme temperatures.
- If the device will not be used for an extended period, remove the batteries to prevent potential damage from battery leakage.
- Handle the sensor with care to avoid damage, as it is a critical component for accurate measurements.
9. Troubleshooting
- No Display/Power On: Check battery installation and ensure batteries are not depleted. Replace if necessary.
- Unstable Readings: Ensure the sample is properly placed and the measuring chamber is securely combined with the sensor. Allow sufficient time (at least 5 minutes) for the reading to stabilize. Environmental factors like temperature fluctuations can also affect stability.
- Inaccurate Readings: Perform a reading correction as described in Section 6. Ensure the sample plate is clean and free from residue.
- Connection Issues with PC: Verify that the USB software is correctly installed and the cable is securely connected. Ensure the meter is powered on and displaying the reading screen before attempting connection.
10. User Tips
- For best results, ensure the sample material is finely ground or spread evenly in the sample dish to maximize surface area exposure to the sensor.
- Avoid placing the meter in direct sunlight or near heat sources during measurement, as temperature can influence water activity readings.
- When measuring multiple samples, allow a brief period between measurements for the sensor to re-equilibrate, especially if there are significant differences in water activity between samples.
11. Warranty and Support
This product is covered by a standard manufacturer's warranty. For detailed information regarding warranty terms, technical support, or service inquiries, please contact the authorized seller or the manufacturer directly. Please retain your purchase receipt as proof of purchase for any warranty claims.