Introduction
The PHM-245 is a professional 2-in-1 combo pH and temperature meter designed for accurate measurement and continuous monitoring of pH levels and temperature in various solutions. It is equipped with Automatic Temperature Compensation (ATC) to ensure high accuracy, as pH values can vary with temperature. The device features a clear, dual display that shows both pH and temperature readings simultaneously, and a backlight for use in dark environments. It is ideal for applications in laboratories, agriculture, industrial settings, and field water analysis, including aquariums, hydroponics, pools, tanks, and spas.
The PHM-245 pH and Temperature Monitor with its probes.
Package Contents
Please check the package to ensure all items are present:
- 1 x pH/Temp Meter
- 1 x Removable BNC pH Electrode
- 1 x Fixed Temperature Probe
- 1 x Mini Screwdriver (for calibration)
- 1 x Clip Holder
- 1 x Rubber holder with suction cap
- 4 x 1.5V AG13 button batteries
- 1 x Power adapter
- English User Manual
- Sturdy Carrying Case
All components included in the PHM-245 package.
Setup
1. Power Supply
The PHM-245 can be powered by either 4 x 1.5V AG13 button batteries or the provided power adapter. For continuous monitoring, using the power adapter is recommended.
- Battery Installation: Open the battery compartment on the back of the unit and insert 4 x 1.5V AG13 button batteries, ensuring correct polarity.
- Power Adapter Connection: Plug the power adapter into the DC input port on the side of the monitor.
The 4-slot battery compartment for AG13 button batteries.
2. Connecting Electrodes
Connect the BNC type pH electrode and the fixed temperature probe to their respective ports on the monitor. The BNC connector for the pH electrode should be securely twisted into place.
Detail of the BNC interface for the pH electrode connection.
The fixed temperature probe.
Operating Instructions
1. Power On/Off
Press the power button (U) on the front panel to turn the device on or off.
2. Temperature Unit Selection
Press the '°C/°F' button to switch between Celsius and Fahrenheit temperature units.
3. Taking Measurements
Once powered on and electrodes are connected, submerge both the pH electrode and temperature probe into the solution you wish to measure. The pH and temperature readings will be displayed simultaneously on the LCD screen. Allow a few moments for the readings to stabilize.
The PHM-245 monitor displaying pH and temperature readings in an aquarium.
4. Calibration (pH Meter)
To ensure accurate pH readings, regular calibration is essential. The PHM-245 uses a 1-point manual calibration method. It is recommended to calibrate using pH 6.86 buffer solution first, then verify with pH 4.01 and pH 9.18 solutions.
- Preparation: Prepare the pH 6.86, pH 4.01, and pH 9.18 buffer solutions according to their instructions (typically by dissolving powder in distilled water). Have a separate container of distilled water and clean tissues ready for rinsing.
- Rinse Electrodes: Wash both the pH electrode and temperature probe with distilled water and gently wipe them with a clean tissue.
- Calibrate with pH 6.86: Submerge both electrodes into the pH 6.86 buffer solution. Ensure the electrodes are fully submerged.
- Adjust Trimmer: Once the reading on the display stabilizes, use the provided mini screwdriver to carefully turn the calibration trimmer (usually located on the side or back of the unit) until the display shows 6.86. (Note: A display value within the acceptable error range of +/- 0.1 pH is considered calibrated).
- Rinse Again: Remove the electrodes from the buffer solution, rinse them thoroughly with distilled water, and gently wipe with a clean tissue.
- Verify with pH 4.01 and pH 9.18: Repeat steps 3-5 for pH 4.01 and pH 9.18 buffer solutions to verify the accuracy across the range. The readings should be within +/- 0.1 pH of the buffer values. No further adjustment is needed if the 6.86 calibration was successful and other points are within tolerance.
Video demonstrating the pH meter calibration process using buffer solutions.
Maintenance
1. Electrode Cleaning
Always rinse the pH and temperature electrodes with distilled water after each use to prevent contamination from samples and ensure accurate readings for future tests. Gently wipe them with a clean, soft tissue. Avoid abrasive materials that could scratch the electrode surface.
2. Electrode Storage
Store the pH electrode with its protective cap on. For optimal performance and longevity, keep the pH electrode bulb hydrated by storing it in a pH electrode storage solution or a pH 7 buffer solution. Do not store it in distilled water, as this can deplete the electrolyte in the electrode.
3. Battery Replacement
When the display dims, readings become unstable, or the device does not power on, it is time to replace the 4 x 1.5V AG13 button batteries. Ensure the device is off before replacing batteries.
Troubleshooting
- Inaccurate or Unstable Readings:
- Ensure electrodes are clean and free from residue.
- Perform a full calibration with fresh buffer solutions.
- Check if the temperature probe is correctly submerged and functioning, as ATC relies on accurate temperature.
- If the pH electrode is old (typically over 1-2 years), it may need replacement.
- No Display or Device Not Powering On:
- Check battery installation and ensure batteries are not depleted. Replace if necessary.
- If using the power adapter, verify it is securely connected and the power outlet is functional.
- Slow Response Time:
- Clean the electrodes thoroughly.
- The pH electrode may be nearing the end of its lifespan and require replacement.
Specifications
| Feature | Specification |
|---|---|
| Measuring Range (pH) | 0.00~14.00pH |
| Measuring Range (Temperature) | 0~55°C (32~131°F) |
| Resolution (pH) | 0.01pH |
| Resolution (Temperature) | 0.1°C |
| Accuracy (pH) | ±0.1pH |
| Accuracy (Temperature) | ±1°C |
| Automatic Temperature Compensation (ATC) | 0~50°C (32~122°F) |
| Environmental Condition | 0~50°C (32~122°F); Humidity ≤95% |
| Power Supply | 6V DC or 4 x 1.5V AG13 button battery |
| Display Type | DIGITAL |
| Backlight | Yes |
| Certification | CE |
User Tips
- For best accuracy, always calibrate the pH meter before critical measurements, especially after prolonged storage or if readings seem inconsistent.
- Keep buffer solutions fresh and at the correct temperature for calibration. Expired or contaminated buffer solutions will lead to inaccurate calibration.
- The separate pH and temperature electrodes allow for more precise measurements by isolating the sensing elements, reducing potential interference.
- The backlight feature is particularly useful when working in dimly lit environments, ensuring clear visibility of readings.
Warranty and Support
This product includes a comprehensive English User Manual to guide you through its features and operation. It is also supplied with a sturdy carrying case for protection and portability. For technical support, warranty claims, or further inquiries, please refer to the contact information provided by your specific seller or retailer at the time of purchase. Please retain your proof of purchase for any warranty-related services.
