These sensors are particularly used to detect different gases. You must select a particular sensor to obtain proper sensing of the particular gas. So study this rigorously tested comparative analysis of these sensors, in Vidyasagar Academy Lab.
| Feature | MQ135 | MQ136 | MQ137 | MQ7 |
| Prominent Gas Detection | CO2, NH3, NOx, Benzene, Alcohol, Smoke | Hydrogen Sulfide (H₂S) | Ammonia (NH₃), Benzene, Alcohol | Carbon monoxide (CO) |
| Sensitivity Range | 10 – 1000 ppm | 1 – 200 ppm | 5 – 500 ppm | 20-2000 ppm |
| Typical Detection Gases | CO2, NH3, Benzene, Smoke, Alcohol | Hydrogen Sulfide (H₂S) | Ammonia (NH₃) | Carbon monoxide (CO) |
| Operating Voltage | 5V | 5V | 5V | 5V |
| Preheat Time | 24 hours | 24 hours | 24 hours | 48 hours |
| Heating Voltage (VH) | 5V AC or DC | 5V AC or DC | 5V AC or DC | 5V AC/DC (1.4V alternating cycles) |
| Load Resistance (RL) | 20kΩ | 20kΩ | 20kΩ | 10kΩ |
| Sensitivity Adjustment | Adjustable by varying RL | Adjustable by varying RL | Adjustable by varying RL | Adjustable by varying RL |
| Output Signal | Analog | Analog | Analog | Analog |
| Response Time | ≤ 10 seconds | ≤ 10 seconds | ≤ 10 seconds | ≤ 20 seconds |
| Recovery Time | ≤ 30 seconds | ≤ 30 seconds | ≤ 30 seconds | ≤ 60 seconds |
| Operating Temperature | -10°C to +50°C | -10°C to +50°C | -10°C to +50°C | -10°C to +50°C |
| Relative Humidity Range | 20% – 90% | 20% – 90% | 20% – 90% | 10% – 90% |
| Power Consumption | Less than 800 mW | Less than 800 mW | Less than 800 mW | Less than 350 mW |
| Applications | Air quality monitoring, smoke detection | Detecting H₂S in various industries | Ammonia detection, air quality monitoring | Carbon monoxide detection in exhaust, indoor air monitoring |
- MQ135 is a general-purpose sensor that can detect multiple gases like CO2, NH3, NOx, and others, making it suitable for air quality monitoring.
- MQ136 is specialized for detecting Hydrogen Sulfide (H₂S).
- MQ137 is designed for Ammonia (NH₃) detection and is less responsive to gases other than ammonia compared to the MQ135.
- The MQ7 differs significantly due to its alternating heating voltage requirement and its specialized focus on carbon monoxide, unlike the MQ135, MQ136, and MQ137, which are broader in their detection ranges.