Labmate LMPHM-A100 Portable Water Hardness Meter

Index

1. Introduction

The Portable Water Hardness Meter LMPHM-A100 features a solid-state ion selective electrode and an LCD display. Manual temperature calibration enhances measurement accuracy. Stored data can be transferred to a computer via USB communication. The system menu allows setting 7 parameters, including calibration points, stability condition, hold function, and auto-power off. A stability indicator automatically shows the current measurement status.

2. Features

• Suitable for outdoor applications.
• Automatic temperature compensation for accurate readings across the entire range.
• Automatic power off conserves battery life.
• Setup menu allows adjustment of stability criteria and number of calibration points.
• 2 to 5 points calibration system covering low to high concentration extents.
• Expanded memory stores up to 500 data sets.
• Multi-mode power scheme (battery, power adapter, computer's USB port) ensures smooth operation.

3. Specifications

4. Applications

Used for testing the hardness level of tap water, drinking water, and in food, research centers, and industries.

5. Installation

5.1 Display

The meter's display indicates various modes and statuses:

• Measurement Modes: pH, ORP, ION, DO, COND, TDS, SAL, RES, Dissolved Oxygen.
• Status Indicators:
• Stable: Indicates a stable measurement.
• HOLD: Indicates the reading is locked.
• [Measure Icon]: Meter is in measurement mode.
• [Calibration Icon]: Meter is in calibration mode.
• [Setup Icon]: Meter is in setup mode.
• [Memory Icon]: Viewing stored readings or data in memory.
• Slope Icon: Disappears if electrode slope exceeds the allowed range after calibration. Appears if recalibration is due.
• [Bell Icon]: Automatic temperature compensation is enabled.
• Stable: Shown when the measurement is stable.
• HOLD: Shown when the reading is locked.

Key Functions:

5.3 Connectors

The meter has the following connectors:

1. Socket for pH, ORP, or ion selective electrode (BNC).
2. Socket for temperature probe (3.5 mm jack).
3. Socket for dissolved oxygen electrode (6-pin DIN).
4. Socket for conductivity electrode (6-pin DIN).
5. Socket for reference electrode (3.5 mm jack).
6. USB-B interface for power adapter or computer connection.

6. Operations

6.1 Before use

1. Connect the water hardness electrode to the meter.
2. Remove the protective cap and soak the electrode in a 10 mmol/L standard solution for approximately 10 minutes. [Image showing electrode soaking in solution for 10 minutes]

6.2 Selecting the Measurement Mode

The meter supports 8 water hardness measurement modes. Press the Mode key to cycle through and select the desired measurement mode. The display will show the corresponding icon.

Note: Setup menu and calibration can only be performed in the ION mode.

6.3 Water Hardness Settings

The meter has 1 measurement setting and 7 general settings accessible via the setup menu.

6.4 Temperature Compensation

For accurate measurements, ensure standards and samples are at the same temperature. Temperature compensation can be enabled automatically or manually.

• Automatic Temperature Compensation: Connect the temperature probe. The ATC icon will appear on the display, indicating the meter is in automatic compensation mode. [Diagram showing ATC connection and display with temperature]
• Manual Temperature Compensation: If the temperature probe is not detected, the °C icon appears, indicating manual mode. To set the temperature:
1. Press and hold the °C key to enter temperature setting.
2. Use the ▲ / ▼ keys to adjust the temperature value.
3. Press Enter to save.
• Note: Pressing and holding ▲ / ▼ speeds up value changes.

6.5 Water Hardness Calibration

The meter supports 2 to 5 point calibration using standard solutions. Acceptable calibration points include:

For improved accuracy, add an ionic strength adjuster (ISA) to standards and samples. A typical addition is 2 ml of ISA per 100 ml of standard/sample.

Calibrating the meter:

1. Press the Mode key until the display shows the ion concentration measurement mode. [Image showing Mode key and display]
2. Press the Cal key to enter calibration mode (displays 0.001 mmol/L / CAL1).
3. Use the ▼ key to select the first calibration point (e.g., 0.01 mol/L). The meter calibrates from low to high concentrations. [Image showing calibration display with CAL 1]
4. Rinse the electrode with deionized water, then with a small amount of standard solution. Place the electrode (and temperature probe) into the standard solution (e.g., 10 mmol/L) and stir gently. [Diagram showing rinsing and immersing electrode in solution]
5. Press the Enter key; the Calibration icon will flash. [Image showing Enter key and flashing calibration icon]
6. When the reading stabilizes, the display shows 0.1 mol/L/CAL2, prompting for the second point calibration. [Image showing CAL 2 prompt]
7. Rinse the electrode with deionized water and a small amount of standard solution. Place the electrode (and temperature probe) into the next standard solution and stir gently. [Diagram showing rinsing and immersing electrode in solution]
8. Press the Enter key; the Calibration icon will flash. [Image showing Enter key and flashing calibration icon]
9. When the reading stabilizes, the display shows CAL3, prompting for the third point calibration.
10. Repeat steps 7 and 8 until calibration is complete. To exit without saving, press the Meas key.

Note: The meter is packaged with 10 and 100 mmol/L standard solutions. Calibration points are 0.01 and 0.1 mol/L. 1 mol/L = 1000 mmol/L.

Viewing the Calibration Log

1. In measurement mode, press the MR key and then the ▼ key until the meter shows / (Electrode).
2. Press Enter; the meter displays the last calibration date. [Image showing date display]
3. Press the ▼ key to view the calibration point and mV value. [Image showing calibration point and mV value]
4. Press the ▼ key to view the next data set.
5. Press the Meas key to exit the calibration log.

Note: If the meter is not calibrated with standard solutions, the display will show ----.

6.6 Water Hardness Measurement

1. Rinse the water hardness electrode with deionized water. Place the electrode (and temperature probe) into the sample solution and stir gently. Note: Ensure the ion-sensitive membrane and liquid junction are fully immersed. [Diagram showing electrode in sample solution]
2. If Auto-Hold is enabled in the setup menu, the meter automatically senses a stable reading and locks it (HOLD icon appears). Press Meas to resume measuring. If disabled, the meter continuously measures and updates readings. [Image showing HOLD icon and measurement display]
3. Wait for the measurement to stabilize and record the reading.
4. After measuring all samples, rinse the electrode with deionized water.
• Important: During measurement, do not wipe the ion-sensitive membrane. Blot dry with a lint-free tissue to remove water drops.
• If the meter is not calibrated with the connected electrode, the display will always show 0.000.
• If the meter displays ----, indicating the measurement exceeds the range, remove the electrode from the sample immediately.

7. Maintenance

Electrode Maintenance

1. After use, rinse the water hardness electrode thoroughly with deionized water. Wipe clean with a lint-free tissue, replace the protective cap, and store the electrode in a dry, cool, well-ventilated area.
2. Do not scratch the ion-sensitive membrane at the bottom of the electrode.
3. If the electrode response becomes sluggish, soak it in a 10 mmol/L standard solution for at least 1 hour. [Diagram showing ion-sensitive membrane]

Preparation of Standard Solution (100 mmol/L)

1. Fill a 1-liter volumetric flask halfway with deionized water. Add 14.7 grams of analytical-grade calcium chloride (CaCl2 · 2H2O) reagent.
2. Gently swirl the flask to dissolve the reagent. Fill to the mark with deionized water.
3. Cap the flask and invert several times to mix the solution.

8. Troubleshooting

(Troubleshooting information would typically follow here, but is not present in the provided pages.)