Biolab BMET-202 pH Meter Operating Manual

1. Introduction

1.1 Introduction

The BMET-202 portable pH meter is a versatile instrument designed for a wide range of applications in universities, environmental protection, medicine, food, sanitation, geological prospecting, metallurgy, ocean exploration, and various industries for measurements such as acid rain detection, industrial wastewater, surface water, drinking water, beverages, daily chemical products, and textiles.

General Features:

• High resolution LCD display, 5.7 inches.
• Multi-reading capability, allowing auto-read, timed-read, and continuous-read.
• Automatic/Manual temperature compensation for accurate results.
• Auto-hold feature to sense and lock the measurement endpoint.
• Data storage for up to 500 sets (GLP-compliant).
• Support for USB or RS-232 communication.
• Reset feature to restore all settings to factory default options.
• IP54 waterproof rating.
• 1-5 points calibration with standard recognition.
• Selectable pH buffer groups, including NIST, DIN, GB, USA.
• Automatic electrode diagnosis with pH slope and offset display.

1.2 Technical Specification

1.3 Function Introduction

2. Safety Notices

Please read the entire contents of this manual carefully before use, and keep this manual properly. The user must use the instrument following this manual to avoid damage to the user and equipment.

Before using the meter, READ the following notes:

• DO NOT DISASSEMBLE the device for inspection or repair.
• To prevent electric shock or damage to the device, DO NOT place cables and connectors in any liquid, wet or corrosive environment.
• Please use the defaulted power adapter; DO NOT use it if the power cord is damaged (the wire is exposed or broken).
• DO NOT use in flammable and explosive environments.
• DO NOT use if the user finds any abnormalities such as damage or deformation of the device.

The following identifiers will be used in this manual:

[TIPS] Tips help to use the meter.

3. Terms Explanation

• pH Slope: The amount of potential change generated by each 1 pH change, expressed in mV/pH or by 100% Theoretical Slope (PTS). pH = -log[H], where [H] means molar concentration (mol/L) of H ions.
• E0 of pH: Also known as "zero potential", it usually refers to the potential value at a pH of 7.
• One-point calibration: Calibration with a standard solution.
• Two-point calibration: Calibration with two standard solutions.
• Multi-point calibration: Calibration with more than two standard solutions.

4. Overview and Installation

4.1 Overview

Figure 4-1 Overview-Front view: Shows the front of the pH meter, including the meter body, display, power key, function selection keys, electrodes stand, and pH electrode.

Figure 4-2 Overview- Back view: Shows the back of the pH meter, including the temperature electrode socket, ground socket, measuring electrode socket, reference electrode socket, RS232 socket, USB socket, and DC9V power socket.

Figure 4-3 Electrodes and connectors: Shows the electrode protection cap, pH electrodes, temperature electrode connector, pH electrode connector, and Q9 shorting connector.

4.2 Instrument Installation

4.2.1 Electrodes Stand Installation

1. Pull out the electrode holder fixing plate on the right side of the instrument.
2. Press the electrode holder support onto the vertical shaft of the electrode holder drawer.
3. Tighten the set screw at the bottom of the electrode holder support.

4.2.2 Electrodes Connection

1. Mount the pH electrode (15) on the electrode holder (5).
2. Find the measuring electrode socket (9) on the back of the instrument, unplug the Q9 short circuit plug (18), then, insert the pH electrode into the measuring electrode socket (9).
3. Insert the other four-pin aviation of the pH electrode into the temperature electrode socket on the back of the instrument.

Figure 4-4 Electrode stand installation: Illustrates the electrode stand installation with components like damping adjusting nut, electrode rack arm, electrode holder, electrode stand, fixing screws, fixed vertical shaft, and fixed plate.

5. Instrument Operation

5.1 Switch On/Off

After connecting the power adapter, the electrode holder and electrode, press and release the power button to switch on the meter. The startup screen displays software version and other related information. After the self-test program, the screen turns to the homepage, and the meter is ready to measure. To shut down, press and hold the power button for more than 3 seconds and then release.

5.2 Screen Icons

The instrument displays symbol identification with the following functional implications:

5.3 Function Key

5.4 Instrument Settings

In the standby interface or during the measurement process, instrument parameters can be set using the "Setting" soft function key.

5.4.1 Tutorial settings

For the first use, follow the guide to set the measurement parameters. After all settings are done, press "Enter" to return to the previous page.

5.4.2 Reading Mode Settings

The meter offers three reading modes: continuous readings, auto readings, and timed readings.

• Continuous reading: Displays real-time measurement results. The user can end the measurement at any time and save the last result.
• Auto-reading: The measurement reaches balance, and the meter locks the reading result. The meter offers "Fast", "Medium", "Strict", and "Custom" options for endpoint detection conditions.
• Time reading method: Timed Reading includes "Interval Measurement" (results at intervals) and "Timed Measurement" (results after a set time).

5.4.3 pH Parameter Settings

5.4.3.1 pH standard groups

The pH electrode requires calibration with a pH standard buffer solution. Different regions use different standards. The instrument has built-in GB, DIN, and NIST standard solutions. Custom standard solution groups can also be created.

Figure 5-3 Selection of standard groups and standard solution: Shows the interface for managing pH groups and selecting standard solutions for calibration. A check mark indicates the currently used standard solution group.

[TIPS] Selecting the correct standard solution group is crucial for accurate electrode calibration. Using a different group than the actual pH standard buffer solution used can lead to incorrect calibration results.

5.4.3.2 Recognition

For non-standard pH buffer solutions or very close standard buffer solutions, the manual standard solution identification function can be used. In "Manual Mode", the pH value of the current standard solution can be input during calibration.

5.4.3.3 Resolution setting

The pH measurement resolution is adjustable: 0.01pH and 0.1pH. The mV resolution is adjustable: 0.1 mV and 1 mV.

5.4.4 Temperature Parameter Settings

The temperature unit can be selected as °C or °F. Temperature compensation modes are ATC (automatic) and MTC (manual).

5.4.5 Data Management Settings

5.4.5.1 Sample ID type

Supports three methods: Number order (increasing series number), Time order (increasing with sample measuring time, format: Year/Y, Month/M, Day/D, Hour/H, Minutes/M, Second/S), and Manual (manually set Sample ID).

5.4.5.2 Result Autosave

When enabled, saves results when the reading is stable in auto-reading and interval timed reading modes.

5.4.5.3 Data Overwrite

The meter has a storage space of 500 sets of measurement results. When enabled, data exceeding capacity will overwrite old results.

5.4.6 Output option

Data format can be GLP, STD Format, or Custom.

5.4.7 User ID Settings

Allows setting the user ID.

5.4.8 System Parameter Settings

5.4.8.1 System Date & Time

Settings for system date and time.

5.4.8.2 Buzzer setting

Users can set the key sound.

5.4.8.3 Brightness setting

Users can adjust the screen brightness.

5.4.8.4 Auto Power off

The meter features auto shutdown. It switches off automatically when not in use.

5.4.8.5 Restore Default

Supports "Restore Default" (restores all parameters to factory state) and "Restore Parameters" (restores measurement parameters to factory state).

5.4.8.6 Software version

Software version information can be found on the general setting page.

5.5 pH Measurement

5.5.1 Calibration Preparation

The electrode slope and zero potential of pH electrodes can drift over time. For accurate pH measurement, it is recommended to calibrate the pH electrode before use. The instrument supports 1-5-point calibration.

• One-point calibration: A calibration process with a single standard solution, typically used for quick tests. The calibration slope is 100%.
• Two-point calibration: Uses two pH standard buffer solutions to calibrate the electrode and construct a linear calibration curve. This is the most common method and is recommended when the pH value of the solution to be measured lies between the two standard buffer solutions. It improves pH measurement accuracy.
• Multi-point calibration: A calibration process with more than one standard solution. It is recommended to calibrate between two standard buffer solutions at the pH of the solution to be tested. Multi-point calibration covers a wider measurement range for accurate pH measurement. Prepare one or more pH standard buffer solutions before starting calibration.

[TIPS] Standard buffer solutions can be prepared or purchased. Refer to the appendix for preparing pH standard buffer. Certified standard buffers can be purchased from professional manufacturers.

5.5.2 Standards group selection

Before calibration, prepare one or more pH standard buffer solutions. The meter has a standards recognition function. Set the Standard Group before measurement. Alternatively, set the identification type to "Manual Mode" and manually enter the nominal value during calibration.

5.5.3 pH Calibration

The calibration process is as follows:

1. Setting: Set parameters (e.g., pH). Select the NIST standard solution group and check pH 4.01, pH 7.00, and pH 10.01 standard solutions. Set the Auto Mode recognition.
2. Connect the ATC probe or enter the temperature manually.
3. Press the F2 "Calibrate" for one-parameter measurements or F2 "Calibrate"-"pH Calibration" for multi-parameter measurements.
4. Place the cleaned electrode into the pH 4.01 standard solution.
5. Wait for the instrument to display "Auto Mode Matched", then press F4 "Start".
6. For 1-point calibration, press "Enter" to complete after calibration.
7. For multi-point calibration, replace with pH 7.00 and pH 10.01 standard buffer solutions. After cleaning the electrode, place it in the standard solution. Once recognized, press F4 "Next Point" to complete the calibration.
8. After calibration, press "Enter" to save results and end calibration. If the standard solution group has 5 points, calibration ends automatically after five points.

Figure 5-4 pH electrode calibration information: Displays the pH calibration status, including the current pH value, temperature, matched standard value, and calibration results.

5.5.4 pH Measurement

The measurement process is as follows:

1. Setting: Set parameters (e.g., pH) and reading mode (continuous, auto, or timed).
2. Place the electrode into the test solution.
3. In idle status, press F4 "Measure" to enter measurement status.
4. When the reading is stable, press "Enter" to read the results.
5. Press "Save" to save the measurement results.
6. Press "Output" to print the measurement result when connected to a printer.
7. Between measurements, store the pH electrode in distilled or deionized water.
8. After measurement, rinse the pH electrode thoroughly with deionized water.

Figure 5-8 pH measurement information: Shows the measurement screen with parameters like pH, mV, temperature, and time.

[TIPS] Ensure the pH and reference electrode are immersed in the sample solution. For high accuracy, conduct measurements in a lab with constant temperature and pressure. If temperatures differ, use a pH combination electrode with temperature compensation or a separate temperature electrode. Alternatively, use a thermometer to measure temperature and set it manually.

5.6 Data Management

Press "Data" to view detailed results. The meter stores measurement results independently for each parameter (pH/pX/ISE/EC/Resistivity/TDS/Salinity/DO/Saturation), with storage for 1000 sets per parameter.

Users can press "Delete" to access the delete menu, allowing deletion of current data or all data.

Data can be viewed by filter (parameter, locate No., or stored date). Press "Start Search" to display filtered data in a graph. Use "←" and "→" to navigate data. Press "Enter" to view detail results. "Delete" removes the current result, and "Output" selects the output data format.

Figure 5-16 Results setting view: Shows the interface for filtering and searching stored results.

Figure 5-16 Review the stored resulted by graph: Displays stored results in a graph format.

[TIPS] Turn off the instrument and printer power before connecting the printer. The instrument communication baud rate is 9600bps, with default settings of 8 data bits, a start bit, and a stop bit, no parity check.

6. Maintenance/Troubleshooting

6.1 Meter Maintenance

Proper use and maintenance ensure accurate and reliable performance. Maintenance is crucial for pH measurements, which are susceptible to static electricity and electromagnetic field disturbances. Exposure to chemicals or harsh environments can affect performance.

• When the pH measuring electrode socket is not connected, insert the Q9 short-circuit plug to prevent damage. Store the plug in a dry, clean environment to prevent corrosion.
• If the instrument is not used for a long time, disconnect the power supply.
• Keep the meter and accessories clean and away from acids, alkalis, and corrosive solutions/gases.
• The housing material is sensitive to organic solvents like toluene, xylene, and MEK. Clean the meter surface with water and detergent.
• Unplug the meter and remove all connected cables.
• Remove the electrode holder.
• For long-distance transportation, use the original packaging to prevent damage.

6.2 Electrodes Maintenance

Before using the electrode, read the electrode manual carefully to understand its type, structure, and application scope. Refer to the electrode instruction manual for more details.

6.3 Troubleshooting

If the meter still does not work, please contact your local dealer for further assistance.

7. Technical Supports

Accessories

Refer to the accessories table for purchasing recommendations.

8. Appendixes

Appendix 1

pH-Temperature Relationship Table of pH Standard Solutions