Target: NH3
Model: MP-702
Detection range: 0-100ppm
Detection principle: Semiconductor
Characteristics: High sensitivity to NH3
Size: φ9.4×7
Working conditions: Loop Voltage:≤24V Heater Voltage:5±0.1V Heater consumption:≤300mW

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MP-702 model with advanced planar construction is comprised of heater and metal oxide semiconductor material of subminiature Al2O3 ceramic plate, fetch out electrode down-lead, encapsulation in metal base and cap. When the target gas exists , The sensor’s conductivity is more higher along with the gas concentration rising. Please use simple electrocircuit, convert change of conductivity to correspond output signal of gas concentration.


It is widely used to detect NH3 gas in fridge, refrigerated storage and agriculture breeding occasion.


It has high sensitivity to NH3 gas, and has advantages such as fast response and recovery, low power consumption, easy test circuit, good stability, long lifespan &etc.


Model MP-701
Sensor Type Flat surfaced Semiconductor
Standard Encapsulation Metal
Target Gas Ammonia Gas(NH3)
Detection range 0~100ppm (NH3)
Standard Circuit Conditions Loop Voltage Vc ≤24V DC
Heater Voltage VH 5.0V±0.1V AC or DC
Load Resistance RL Adjustable
Sensor character under standard test conditions Heater Resistance RH 1Ω±10Ω (room temp.)
Heater consumption PH ≤300mW
Sensorresistance Rs 1kΩ~30kΩ(in 50ppm NH3)
Sensitivity S Rs(in air)/Rs(in 50ppm NH3)≥5
Concentration Slope α ≤0.6(R100ppm/R30ppm NH3)
Standard test conditions Temp.  Humidity 20℃±2℃;65%±5%RH
Standard test circuit Vc:5.0V±0.1V; VH:5.0V±0.1V
Preheat time Not less than 48 hours

* The description and specifications might be changed without notice. Please contact us for the latest information before placing orders.

Technical Support:

Customized technical design and function, LOGO and package are available without extra charge (including molding fee) for mass volume.

The sensors don't have sleeping mode. It can be set in program if needed.

All Winsen products go through strict inspections and tests to make sure they are 100% qualified before shipping out.

The sensor has been fully tested (not calibrated) before leaving the factory. However, after transportation and storage, the environment conditions change, and the surface of the sensor absorbs moisture, mixed gas, pollution matters, etc. It is recommended that customers perform aging and calibration after sensors become stable according to the program and use occasions of the whole device.

15﹪-90﹪RH without condensation,greater or less than this range or long-term high temperature and high humidity will affect the life of the sensor.

Our sensors are certified with CE, 3C, ROHS, anti-explosion, fire prevention, and coal mining safety according to different applications. And we provide assistance for new certification.

Many factors can cause the sensor to fail such as broken wires in transportation, poisoning, falling off of the sensitive material, damage to the heating wire (device), etc. Please find specific cause in each category with Winsen’s aftersales.

Winsen provides professional consultation and service before and after sales. We will recommend the best fitting sensor for your demand. If you have any problem, don’t hesitate to email us to

Due to high volume of daily incoming emails and time zone difference, we may not be able to reply your emails immediately. But we will reply to your inquiry in 24 business hours.