GVDA PH818 Pen Type PH Meter

Introduction

This device is an intelligent, precise measurement apparatus designed with high-quality components and sensors. It offers high sensitivity and accuracy, stable operation across different temperatures, and a compact size for easy storage and portability. The PH818 can measure both pH values and the temperature of the solvent under test. This pH meter is widely applied in industrial, electrical, agriculture, medicine, and food industries. Please read this instruction manual thoroughly before use to ensure correct readings and proper operation.

Product Overview

The PH818 pH meter features a clear LCD display and intuitive button layout for ease of use. Key components and display elements are detailed below.

Components and Controls

1. Power ON/OFF / and Hold button
2. Calibrate / increase button
3. Back light / reduce button
4. PH value reading area
5. Temperature reading area
6. PH Probe Electrode

LCD Display Screen

• Timer icon
• PH measured value
• Data Hold icon
• Environmental temperature
• Measured value
• Battery power indication
• Calibration mode icon
• Temperature unit °C/°F

Technical Specifications

Setup

Battery Installation

Open the battery door located at the top of the instrument. Insert two AAA size (1.5V) batteries into this compartment, ensuring correct polarity. The product is shipped without batteries.

Calibration

If you have replaced the PH composite electrode or are using the instrument for the first time, calibration is required. If measuring interval time is short, monthly calibration is sufficient. This instruction uses a three-point calibration method.

Note: The calibration powder is NOT included with the product. Users must purchase calibration powder separately.

1. Ensure the unit and calibration solution are at an ambient temperature of 25°C +/-2°C. In normal measurement mode, press the [CAL/▲] key for more than 3 seconds to enter calibration mode 1.
2. The LCD screen will flash "CAL1" and display "4.00". Rinse the PH electrode with distilled water. Immerse the electrode in the PH4.00 buffer solution. Once the instrument detects a stable signal, the LCD will show "PAS", indicating successful PH4.00 calibration. The unit will then automatically proceed to CAL 2 mode, with "CAL2" flashing and "6.86" displayed.
3. Clean the sensor electrode quickly with distilled water. Immerse the electrode in the PH6.86 buffer solution. Once stable, "PAS" will be displayed, indicating successful PH6.86 calibration. The unit will then automatically proceed to CAL 3 mode, with "CAL3" flashing and "9.18" displayed.
4. Clean the sensor electrode quickly with distilled water. Immerse the electrode in the PH9.18 buffer solution. Once stable, "PAS" will be displayed, indicating successful PH9.18 calibration. The unit will then return to normal measurement mode.
5. If the displayed PH value does not match your buffer solution, you can adjust the value in calibration mode using the [CAL/▲] or [▼] keys, then proceed with the calibration procedure as mentioned above.

Operation

Normal Measurement Mode

The factory default mode is normal measuring mode. To turn on the unit, press the [ON/OFF/HOLD] button. The unit will enter normal measurement mode, displaying both PH and environmental temperature. Immerse the electrode into the solution you wish to measure.

Button Functions

• [ON/OFF/HOLD] key: Press once to turn on. After turning on, press once to hold the measured PH value data. Press and hold for more than 3 seconds to turn off.
• [CAL/▲] key:
  • In normal measurement mode, press for more than 3 seconds to enter Calibration mode.
  • In CAL mode, press to increase the value. Press and hold for more than 3 seconds to increase the value more quickly.
• [▼] key:
  • In normal measurement mode, press to turn on or off the backlight.
  • In CAL mode, press to reduce the PH value. Press and hold for more than 3 seconds to reduce the value more quickly.

Automatic or Manual Power Off Setup

Before turning on the unit, press and hold both [ON/OFF/HOLD] and [CAL/▲] keys simultaneously. The unit will enter "Auto power off" mode setup screen, displaying "APO ON" or "APO OFF". Press [ON/OFF/HOLD] to toggle between "APO ON" and "APO OFF". Once your selection is made, press and hold [ON/OFF/HOLD] for more than 3 seconds to save the setting and return to normal measurement mode.

• APO ON mode: The LCD screen will show a timer icon, indicating that auto power off is selected. If no key is pressed, the unit will power off after 15 minutes.
• APO OFF mode: The LCD screen will not show a timer icon, indicating that you must manually turn off the unit by pressing [ON/OFF/HOLD] key.

Temperature Unit Selection (°C/°F)

Before turning on the unit, press and hold both [ON/OFF/HOLD] and [▼] keys simultaneously. The unit will enter temperature unit selection mode, displaying °C or °F. Press [ON/OFF/HOLD] to toggle between °C and °F. After selection, press and hold [ON/OFF/HOLD] for more than 3 seconds to save the setting and return to normal measurement mode.

Over Range Light Alarm Function

The device features a double-color backlight display to indicate pH levels. If the measured PH value is lower than 3.5PH, the red backlight will turn on, alerting the user that the liquid is strongly acidic. If the measured PH value is higher than 12.5PH, the red backlight will also turn on, indicating a strongly alkaline liquid.

Maintenance and Care

Proper maintenance is crucial for the longevity and accuracy of your pH meter, especially given its use in various chemical environments.

When to Re-calibrate

The instrument must be re-calibrated under the following circumstances:

• The solution temperature has a large difference from the calibrated temperature.
• The PH electrode has been out of its liquid storage bottle for a long time.
• A new PH electrode has been installed.
• After measuring highly concentrated acid (PH<2) or alkali (PH>12) solutions.
• After measuring fluoride solution and acidity within PH<7 or concentrated organic solutions.
• When calibrating, ensure the buffer solution temperature is 25°C +/-2°C.

Instrument Care

• The input port (PH composite electrode) must be kept in good, dry, and clean condition. Do not remove the plug from the unit unless you are sure it will not be used for a long period.
• The head of the PH composite electrode is very delicate and thin. Avoid touching it with hard objects to prevent damage.
• Do not allow dirty substances to contact the head of the composite electrode. If it becomes dirty, clean it with medical soft cotton or a 0.1mol/L dilute hydrochloric acid solution.
• If the head of the PH composite electrode cracks or ages (e.g., after more than one year of stock), it must be replaced with a new PH composite electrode. Otherwise, it may cause slow response or significant measurement errors. New electrodes should be immersed in a 3 mol/L potassium chloride solution for 24 hours before use.
• The accuracy and reliability of the buffer solution are critical for calibration. If the buffer solution's accuracy is low, it will cause significant measurement errors.

Preparation of Buffer Solution (Appendix)

• PH4.00 buffer solution: Dissolve PH4.00 powder in 250mL distilled water, mix carefully until fully dissolved, then let it sit for 30 minutes.
• PH6.86 buffer solution: Dissolve PH6.8 powder in 250mL distilled water, mix carefully until fully dissolved, then let it sit for 30 minutes.
• PH9.18 buffer solution: Dissolve PH9.18 powder in 250mL distilled water, mix carefully until fully dissolved, then let it sit for 30 minutes.

Special Care Notes

• Before use, it is highly recommended to calibrate the instrument with a precise and reliable buffer solution whose pH value is close to the object solution.
• After removing the protection bottle, do not touch the glass bulb or contact it with hard objects, as it is very fragile. Any scratch or crack will cause malfunction.
• After use, place the electrode back into the protection bottle. Ensure the bottle contains enough de-ionized water or rinse solution (tap water) before next use.
• The buffer solution for the reference and compare electrode is 3.3mol/L Potassium chloride solution. Users can refill it into the small hole on top of the composite electrode that is sealed with a silicone rubber tag.
• The contact pin of the electrode must be kept dry and clean, and absolutely cannot be short-circuited, otherwise the electrode will be damaged and cannot be repaired.
• Avoid immersing the PH composite electrode into distilled water, protein solution, Fluorine chemicals acid solution, and avoid contact with silicone grease.
• If the PH composite electrode's sensitivity decreases after long-term use, immerse the head side of the electrode in a 4%HF solution (Hydrofluoric acid) for 3-5 seconds, then clean it with distilled water, and immerse it into Potassium chloride solution to recover it.
• If the measured solution makes the glass bulb dirty or blocks its surface, clean the electrode with a suitable solvent to restore sensitivity. Be careful when selecting cleaning solvents, as some can dissolve polycarbonate resin and damage the glass bulb.
• Important: Unplug the plug of the top side of the electrode to balance air pressure.

Warm Reminder (Figure Show)

Troubleshooting

• Low Battery Indication: If the battery power indicator icon on the top right-hand side of the LCD becomes empty, replace the two AAA size batteries immediately. If the instrument will not be used for a long period, remove the batteries to prevent leakage.
• Over Range Alert: If the measured PH value is lower than 3.5PH or higher than 12.5PH, the red backlight will turn on.
• Temperature Display: If the environment temperature is below 0°C, the LCD screen will show "LO". If the environment temperature is higher than 70°C, the LCD screen will show "Hi".
• Inaccurate Readings / Slow Response: This can be caused by a dirty or aged probe, or incorrect calibration. Refer to the 'Maintenance and Care' section for cleaning and re-calibration procedures. Ensure the probe is properly stored in liquid when not in use.

User Tips

• Many users find this pH meter to be a reliable and good quality product, offering excellent value. Consistent performance makes it a worthwhile investment for repeated use.
• Always ensure the probe is clean and properly calibrated for the most accurate results.

Frequently Asked Questions (FAQ)

No common questions are available at this time. Please refer to the manual sections for detailed instructions or contact support if you have specific queries.

Warranty and Support

Our company reserves the right to change the design and the user manual without prior notice to the end user. For further assistance or inquiries, please refer to the official product page or contact the GVDA Official Store.

A PDF version of this user manual is available for download: View User Manual (PDF)