MQ318 Formaldehyde Sensor
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Air freight costs are based on the weight of the product (including packaging bags and cushioning materials). For products under 2kg, freight is calculated in 50g increments. For products between 2kg and 4kg, freight is calculated in 100g increments. For products over 4kg, freight is calculated in 1kg increments.
If your order exceeds 4kg or the shipping cost exceeds $70, we recommend contacting our customer service for an accurate shipping quote. You will need to provide your zip code address when you contact us.
Air freight options include DHL, UPS, FedEx, and Yun Express, with a delivery time of 7-12 days.
When the weight of the express delivery exceeds 12kg or air shipping cost exceeds US$100 or sea shipping cost exceeds US$50, you can choose B2B shipping:
Air freight(10-14 days)
Yun quik boat sea freight (15-20 days)
Quik boat sea freight(20-25 days).
Air freight B2B express |
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| US Area | Unit Price | Date | Last-mile Delivery |
| Western United States (zip codes starting with 8 or 9) |
US$7.5/kg + US$2 | 10-15 days | UPS / FEDEX / GOFO |
| Central United States (zip codes starting with 4, 5, 6, or 7) |
US$8.5/kg + US$2 | ||
| Eastern United States (zip codes starting with 0, 1, 2, or 3) |
US$9.0/kg + US$2 | ||
Yun quit boat sea freight B2B express |
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| US Area | Unit Price | Date | Last-mile Delivery |
| Western United States (zip codes starting with 8 or 9) |
US$3.4/kg + US$2 | 15-20 days | UPS / FEDEX / GOFO |
| Central United States (zip codes starting with 4, 5, 6, or 7) |
US$3.6/kg + US$2 | ||
| Eastern United States (zip codes starting with 0, 1, 2, or 3) |
US$3.8/kg + US$2 | ||
Quit boat sea freight B2B express |
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| US Area | Unit Price | Date | Last-mile Delivery |
| Western United States (zip codes starting with 8 or 9) |
US$2.6/kg + US$2 | 20-25 days | UPS / FEDEX / GOFO |
| Central United States (zip codes starting with 4, 5, 6, or 7) |
US$2.8/kg + US$2 | ||
| Eastern United States (zip codes starting with 0, 1, 2, or 3) |
US$3.0/kg + US$2 | ||
Processing starts after your payment confirmed. Normally, it needs 2-5 days. The processing time depends on the quantity of items.
The MQ138 gas sensor uses tin dioxide (SnO2), a gas-sensitive material with low conductivity in clean air. When organic vapors are present in the sensor's environment, the sensor's conductivity increases with increasing concentration of organic vapors in the air. A simple circuit can convert this conductivity change into an output signal corresponding to the gas concentration.
The MQ138 gas sensor exhibits high sensitivity to toluene, acetone, ethanol, and formaldehyde, and is also ideal for monitoring hydrogen and other organic vapors. This sensor can detect a variety of organic vapors and is a low-cost sensor suitable for various applications.
This product offers good sensitivity to organic vapors over a wide concentration range and features long lifespan, low cost, and a simple drive circuit.
Detected Gases: Toluene, Acetone, Ethanol, Hydrogen
Detection Concentration: 5～500ppm
Loop Voltage: 5.0V±0.1V DC
Heating Voltage: 5.0V±0.1V AC or DC
Load Resistance: Adjustable
Heating Resistance: 30Ω±3Ω (room temperature)
Heating Power Consumption: ≤950mW
Sensitivity: Rs(in air)/Rs(in 50ppm toluene)≥2
Output Voltage: 0.5V (in 50ppm toluene)
Concentration Slope: ≤0.6(R200ppm/R50ppm toluene)
Temperature and Humidity: 20℃±2℃; 55%±5%RH
Oxygen Content: 21% (not less than 18%, (oxygen concentration affects the sensor's initial value, sensitivity, and repeatability; please consult for use under low oxygen concentration conditions)
Lifespan: 5 years
Preheating time: For first-time use or after a long period of non-power-on, at least 48 hours are required. For daily use, a 2-5 minute warm-up is usually sufficient to reach a stable operating state after powering on.
Regardless of whether the sensor is powered on, prolonged exposure to high concentrations of gas will affect its characteristics. Directly spraying the sensor with lighter fluid will cause significant damage.
When a sensor is stored for an extended period without power, its resistance will experience reversible drift, which is related to the storage environment. Sensors should be stored in sealed bags free of volatile silicon compounds. Sensors that have undergone long-term storage require a longer period of power-on time before use to allow them to stabilize.
Storage Time | Recommended Aging Time
Less than 1 month: Not less than 48 hours
1–6 months: Not less than 72 hours
More than 6 months: Not less than 168 hours