1. Introduction
The AS8900 multi-gas monitor is a portable and handheld instrument designed for continuous and simultaneous monitoring of four gases: Oxygen (O2), Combustible Gas (LEL), Carbon Monoxide (CO), and Hydrogen Sulfide (H2S). All gas readings are displayed on a single LCD screen. The unit allows users to configure high and low alarms, as well as Time Weighted Average (TWA) and Short Term Exposure Limit (STEL) alarms. The device provides audio and visual alarms, along with vibration, when alarm conditions are exceeded.
This manual provides detailed instructions for the proper use, maintenance, and calibration of your AS8900 Multi-Gas Monitor. Please read it thoroughly before operation.
2. Unit Packing List
The standard gift box should contain the following items:
- AS8900 4-in-1 Multi-Gas Monitor: 1 PCS
- Operation Manual: 1 PCS
- Carrying Pouch: 1 PCS
- 3.7V Rechargeable Lithium Battery: 1 PCS
- Charging Adapter: 1 PCS
3. Product Specifications
| Parameter | Value |
|---|---|
| Brand Name | SMART SENSOR |
| Model Number | AS8900 |
| Gas Type | Multifunctional (O2, H2S, CO, LEL) |
| With LCD Screen | Yes |
| Battery Included | Yes (3.7V Lithium-ion) |
| DIY Supplies | Electrical |
| Certification | CE |
| Origin | Mainland China |
| Is Smart Device | No |
| Dimensions | 120.20mm x 64.50mm x 38.30mm |
| Weight | 200g |
| Battery Working Runtime | 18 hours (12 hours with AS8930 sampling pump, at room temperature and no alarm conditions) |
Sensor Specifications:
| Gas | Range | Resolution | T90 |
|---|---|---|---|
| Oxygen (O2) | 0~30% | 0.1% | 10 sec |
| Combustible (LEL) | 0~100% LEL | 0.1% | 35 sec |
| Carbon Monoxide (CO) | 0~999 ppm | 1 ppm | 50 sec |
| Hydrogen Sulfide (H2S) | 0~500 ppm | 1 ppm | 30 sec |
Environmental Conditions:
- Operating Temperature: -10°C to 50°C (except LEL is 0°C to 40°C)
- Operating Humidity: 15~95% RH, typical
- Storage Temperature: 0°C to 40°C
4. Safety Information and Warnings
To ensure safe and proper operation, please observe the following cautions and warnings:
- Always read and follow all procedures and conditions in this manual to prevent instrument failure.
- Insufficient oxygen atmospheres may cause combustible gas readings to be lower than actual corrected readings.
- Enriched oxygen atmospheres may cause combustible gas readings to be higher than actual corrected readings.
- The instrument must be re-calibrated if it has been used in an area where silicon vapors were present.
- Keep the sensor opening and water barriers clean.
- Oxygen readings may fluctuate temporarily if atmospheric pressure changes suddenly.
- Do not charge the battery or service the unit in hazardous or enriched atmospheres.
- This instrument is intended for use by qualified personnel who have fully read and understood this instruction manual.
- High off-scale readings indicate that the environment may have reached an explosive concentration, which is a dangerous condition.
Gas Exposure Limits and Symptoms:
The following tables provide reference information on the effects of various gas concentrations. These parameters are for reference only.
Effect of Oxygen-Deficient and Oxygen-Enriched Atmospheres:
| O2 Concentration (%) | Symptoms (Atmospheric Pressure) |
|---|---|
| 100% | Deadly, 6 minutes (Absolutely airtight environment, such as hyperbaric oxygen chamber) |
| 50% | Deadly, can be cured after 45 minutes treatment. (Absolutely airtight environment, such as hyperbaric oxygen chamber) |
| > 23.5% | Rich oxygen |
| 20.9% | Normal |
| 19.5% | Minimum |
| 15~19% | Reduced efficiency, leading to problems of head, lung, and circulatory system |
| 10~12% | Shortness of breath, loss of judgment, purple lips |
| 8~10% | Governance loss, syncope, unconsciousness, pallor, nausea, and vomiting |
| 6~8% | 8 minutes: blood pressure drop, weak heartbeat, mouth breathing, quickly stopped breathing |
| 4~6% | 40 seconds: convulsions, respiratory arrest, death |
Harm of Carbon Monoxide:
| CO Content in Air | Exposure Time and Symptoms of Poisoning |
|---|---|
| 50 ppm | Maximum (Permissible Exposure Limit) |
| 200 ppm | 2-3 hours: slight headache, dizziness, nausea |
| 400 ppm | 2 hours: forehead pain, life risk after 3 hours |
| 800 ppm | Headache, nausea within 45 minutes, death within 2-3 hours |
| 1600 ppm | Headache, nausea within 20 minutes, death within 1 hour |
Commonly Used Flammable Gas Explosion Limit Table:
| Name | Chemical Formula | Lower Limit LEL (V%) | Upper Limit LEL (V%) |
|---|---|---|---|
| Methane | CH4 | 5 | 15 |
| Ethane | C2H6 | 3 | 15.5 |
| Propane | C3H8 | 2.1 | 9.5 |
| Butane | C4H10 | 1.9 | 8.5 |
| Gasoline (Liquid) | C4-C12 | 1.1 | 5.9 |
| Kerosene (Liquid) | C10-C16 | 0.6 | 5 |
| City gas | - | 4 | - |
| Liquefied petroleum gas | - | 1 | 12 |
| Turpentine (Liquid) | C10H16 | 0.8 | - |
5. Operation Manual
5.1 Instrument Operation
- Power On: Depress and hold the [Power] button for over 1 second. The unit will turn on with a beep sound and vibration. The LCD will light up, showing all icons and segments. After a 18-second countdown, the unit enters Gas Monitoring mode.
- Power Off: Depress and hold the [Power] button for over 3 seconds. The unit will power off after 3 beep sounds.
- Backlight Control: Depress the [Backlight] button to turn the LCD backlight on or off.
5.2 Gas Monitoring Mode
- Once powered on, the display will show all 4 gas symbols with their respective readings.
- The unit continuously monitors and displays gas readings on the LCD. As gas levels increase, the corresponding readings will update to show the current gas concentration.
- The battery life indicator is displayed in the upper left corner. As battery life decreases, the shaded area of the battery icon will also decrease.
- If gas concentration exceeds the high or low alarm limit (or TWA/STEL limits), the unit will trigger audio, visual, and vibration alarms.
5.3 Zero/Calibration Mode
The instrument is recommended to be calibrated for sensitivity with 25% or 50% of full concentration pentane or methane. Refer to this section for detailed zero/calibration procedures.
- From Gas Monitoring mode, depress the [Left Arrow] button once to enter Zero/Calibration mode. The display will show the [Zero] and [Cylinder] icons along with the 4 gas readings.
- To enter this mode, you must key in the correct security code. Press both [Left Arrow] and [Right Arrow] buttons simultaneously in normal gas monitoring mode, then enter the security code.
- Press the [Left Arrow] button 4 times to enter instrument calibration mode. The display will show [Zero] and [Cylinder] icons. Press the [Left Arrow] button again to start calibration (the cylinder icon will flash).
- Ensure the unit is firmly connected to the gas cylinder before the cylinder icon flashes for 6 seconds.
- Press the [Left Arrow] button. The display will show the cylinder and clock with the calibrating value.
- If calibration is successful, the display will show a 'P' icon (Pass). If it shows 'F' (Fail), recalibrate.
- Once the gas concentration drops below the alarm level, the unit will return to normal gas monitoring mode.
- To access Zero/Calibration mode, depress the [Left Arrow] button.
- To start the Zero/Calibration process, depress the [Left Arrow] button. The CO, H2S, and LEL sensors will be zeroed first, then the Oxygen sensor will be spanned.
- During this process, the "CLOCK" icon and full Oxygen span value will be displayed.
- Upon completion, the display will show the SPAN and [Cylinder] icon.
- To calibrate remaining sensors, depress the [Left Arrow] button.
- Calibration gas: Use a blended cylinder containing 25ppm H2S, 100ppm CO, 25% or 50% LEL Methane or Pentane, and 19% Oxygen at 0.5 LPM flow speed.
5.4 Peak Value Setting Mode
- From Zero/Calibration mode, depress the [Left Arrow] button once to enter Peak Value setting mode.
- In this mode, the display shows peak gas readings for the 3 hazardous gases and the lowest reading for the oxygen sensor, along with "PEAK" and "ENTER" icons.
- To reset all peak values, depress the [Left Arrow] button.
- To exit, depress the [Right Arrow] button to enter TWA Value mode.
5.5 TWA Value Mode
- From Gas Monitoring mode, depress the [Left Arrow] button three times to enter TWA (Time Weighted Average) value mode.
- The display will show the "TWA" icon and only the readings for the 2 hazardous and combustible gas sensors.
- TWA values are reset each time the unit is powered off. The time base is set for 8 hours.
5.6 STEL Value Mode
- From Gas Monitoring mode, depress the [Left Arrow] button four times to enter STEL (Short Term Exposure Limit) value mode.
- The display will show the "STEL" icon and only the readings for the 2 hazardous and combustible gas sensors.
- STEL values are reset each time the unit is powered off. The time base is set for 15 minutes.
5.7 Configuration Mode
- To enter Configuration Mode, depress the [Left Arrow] or [Right Arrow] button simultaneously during the 18-second software countdown time after power-on.
- In this mode, you can change high, low, TWA, and STEL alarm levels, as well as the security code.
- Once in Configuration Mode, the security code screen is displayed. The preset code is 123.
- The first digit of the code will flash. Use the [Up Arrow] or [Down Arrow] buttons to change the digit, then press the [Left Arrow] button to set the second and third digits.
- After setting and confirming the security code, depress the [Left Arrow] button to exit to other alarm setting modes.
5.8 Low Alarm Setting Mode
- This is the first configuration screen. The display shows speaker, down, enter icons along with the four low alarm set readings.
- If no change is needed, press the [Right Arrow] button to move to the next setting mode.
- If a change is desired, press the [Left Arrow] button. The first gas low alarm value will flash.
- Adjust the value using the [Up Arrow] or [Down Arrow] buttons.
- Once confirmed, press the [Right Arrow] button to proceed to the next gas low alarm setting.
- Continue this procedure until all 4 gas low alarm values are set. The display will show speaker, down, enter icons along with the 4 new low set alarm values.
- To re-enter this setting mode for further adjustments, depress the [Left Arrow] button.
- To move to the high alarm setting mode, press the [Up Arrow] button.
- To return to low alarm setting mode without saving changes, depress the [Left Arrow] button.
- To return to normal gas monitoring mode, depress the [Left Arrow] button a second time.
5.9 High Alarm Setting Mode
- This is the second configuration screen. The display shows speaker, down, enter icons along with the four high alarm values.
- If no change is needed, press the [Up Arrow] button to move to the next setting mode.
- If a change is desired, press the [Left Arrow] button. The first gas high alarm value will flash.
- Adjust the value using the [Up Arrow] or [Down Arrow] buttons.
- Once confirmed, press the [Left Arrow] button to proceed to the next high alarm setting.
- Continue this procedure until all 4 gas high alarm values are set. The display will show speaker, down, enter icons along with the 4 new set alarm values.
- To re-enter this setting mode for further adjustments, depress the [Left Arrow] button.
- To move to the TWA value setting mode, press the [Up Arrow] button.
- To return to high alarm setting mode without saving changes, depress the [Left Arrow] button.
- To return to normal gas monitoring mode, depress the [Left Arrow] button a second time.
5.10 TWA Alarm Value Setting Mode
- If no change is required, press the [Up Arrow] button to move to the next STEL alarm setting mode.
- If a change is desired, press the [Left Arrow] button. The first gas low alarm value will flash.
- Adjust the value using the [Up Arrow] or [Down Arrow] buttons.
- Once confirmed, press the [Left Arrow] button to proceed to the next gas TWA alarm setting.
- Continue this procedure until all 2 gas TWA alarm values are set. The display will show speaker, TWA, enter icons along with the 2 new TWA alarm values.
- To re-enter this mode for further adjustments, press the [Left Arrow] button.
- To move to the next STEL alarm value setting mode, press the [Up Arrow] button.
- To return to original TWA alarm setting mode without saving changes, press the [Left Arrow] button.
- To return to normal gas monitoring mode, press the [Left Arrow] button a second time.
5.11 STEL Alarm Setting Mode
- In this mode, the display shows speaker, STEL, enter icons along with 2 STEL alarm values.
- If no change is required, press the [Up Arrow] button to move to the next setting screen.
- If a change is desired, press the [Left Arrow] button. The first STEL alarm value will flash.
- Adjust the value using the [Up Arrow] or [Down Arrow] buttons.
- Once confirmed, press the [Left Arrow] button to proceed to the next gas STEL alarm value setting.
- Continue this setting until 2 gas STEL alarm values are set. The display will show speaker, STEL, enter icons along with 2 new STEL alarm values.
- To re-enter this mode for further adjustments, press the [Left Arrow] button.
- To move to the next setting mode, press the [Up Arrow] button.
- To return to the original STEL alarm setting mode without saving changes, press the [Left Arrow] button.
- To return to normal gas monitoring mode, press the [Left Arrow] button a second time.
5.12 Security Code Setting Mode
- This is the security code setting screen. The display will show enter, up/down, enter icons and the manufacturing preset security 123.
- If no change is required, press the [Up Arrow] button to move to other LEL setting mode.
- If a change is desired, press the [Left Arrow] button. The preset code will flash.
- To adjust the first digit, press the [Up Arrow] or [Down Arrow] button. Once the value is confirmed, press the [Left Arrow] button to set the second digit.
- Continue this procedure until all three digits are set. The display will show enter, up/down, enter icons along with the new security code.
- To re-enter this setting mode for further adjustments, press the [Left Arrow] button.
- If no change is needed, press the [Up Arrow] button to move to the next LEL setting mode.
- To return to security mode again without saving changes, press the [Left Arrow] button.
- To return to normal gas monitoring mode, press the [Left Arrow] button a second time.
5.13 LEL Setting Mode
- LEL is the final configuration setting mode. After pressing the [Left Arrow] button, the LEL and value readings will flash.
- Press the [Up Arrow] or [Down Arrow] button to set the new % between 25% and 50%.
- Once the setting is finished, the new value will show on the display. Then press the [Left Arrow] button to confirm.
- Pressing the [Right Arrow] button will return the unit to normal gas monitoring mode.
- If the [Left Arrow] button is pressed, it will return to the first setting mode.
Remarks: LEL (Lower Explosive Limit) is the lowest concentration of a combustible gas in normal air that will ignite.
5.14 Accessory AS8930 Sampling Pump
The AS8930 external sampling pump is available for use with all AS8900 series gas monitors. It is not included in every unit pack.
The pump mounts onto the AS8900 unit using 2 fasten screws. Please refer to the assembly drawing in the full PDF manual for details.
For a detailed visual guide on assembly and operation, please refer to the User Manual (PDF).
6. Maintenance
Follow these guidelines for proper maintenance of your AS8900 unit:
6.1 Cleaning
- Wipe the outside surface of the unit with a soft, clean cloth if necessary.
- Never use any solvents or cleaning solutions.
- Ensure rubber buttons are free of dirt.
- To clean the sensor opening, use a clean, soft cloth or soft brush.
6.2 Charging the Battery
- The lithium-ion battery should be fully charged before initial use.
- To charge, plug the charging lead wire into the charging port at the bottom of the unit. This port is protected by a rubber flap, which must be released before charging.
- The battery should fully charge in 6 hours.
- Once fully charged, the unit can operate for 18 hours, or about 12 hours with the AS8930 external sampling pump (at room temperature and without alarm conditions).
- The shaded area of the battery indicator shows full when the battery is fully charged.
- If only one bar remains on the battery indicator, the battery needs to be charged immediately.
- When the battery is low, the unit may emit a periodic alarm sound to alert you to charge it.
7. Troubleshooting
- Calibration Failure (F icon): If the display shows 'F' during calibration, it indicates that the calibration has failed. You will need to recalibrate the instrument.
- Incorrect Readings: Ensure the sensor opening and water barriers are clean. Verify that the instrument has been calibrated correctly and recently.
- No Standard Gas for Calibration: If no standard gas is available, do not enter the instrument calibration mode, as pre-set values may be easily deleted.
8. User Tips
- Always perform a bump test or calibration check before critical use to ensure sensor accuracy.
- Keep the device in its carrying pouch when not in use to protect it from dust and physical damage.
- Familiarize yourself with the alarm thresholds for each gas to understand when immediate action is required.
9. Warranty and Support
9.1 Warranty
The AS8900 Multi-Gas Monitor is warranted to be free from defects in material and workmanship for a period of one year from the date of purchase.
This warranty does not cover the sensor and battery pack after a 6-month period from the purchase date.
9.2 Manufacturing Statements
Thank you for choosing the Smart Sensor AS8900 Multi-Gas Monitor. This unit has been designed, manufactured, tested, and proven by a professional quality team. It is expected to be reliable under the reasonable care and maintenance described in this instruction manual.
Smart Sensor reserves the right to modify or change the design of the unit, operation manual, or product specifications without prior notice.
10. Disposal
Used or non-functional batteries must be disposed of according to international environmental regulations.
For proper disposal of the device itself, please consult local regulations for electronic waste.