Ammonia Sensors
Select NH₃ sensors for industrial refrigeration, worker safety, livestock ventilation, environmental monitoring and OEM equipment. Compare electrochemical cells, digital modules, metal-oxide sensors and MEMS options by range, response, humidity tolerance and integration method.
Choose the NH₃ sensor around the application
Refrigeration safety, livestock ventilation and process monitoring can all use ammonia sensors, but they operate at different concentrations and need different response, lifetime and installation strategies.
50–200 ppm class
Electrochemical sensors are a common route for quantitative leak detection in machinery rooms, cold stores and industrial refrigeration systems.
- Fast enough for the alarm strategy
- High-humidity tolerance
0–100 ppm class
Use a toxic-gas electrochemical sensor when selectivity, calibration and concentration measurement are more important than heater simplicity.
- Check T90 carefully
- Review overload and exposure life
Low tens of ppm
Continuous ventilation control needs stable low-level tracking over humidity and temperature changes, not simply a wide full-scale range.
- Fixed placement matters
- Condensation must be avoided
0–50 ppm and below
Use a conditioned electrochemical module or a stable low-range cell with good temperature/humidity compensation.
- Low baseline drift
- Short, dry sample path
500–10,000 ppm class
High-range NH₃ sensors are used where normal concentrations exceed personnel-safety ranges, including some agricultural and process measurements.
- Exposure dose can shorten EC life
- Use a range designed for the process
MOS / MEMS / module
Use metal-oxide or MEMS when small size, lower cost or embedded integration outweigh the selectivity advantages of electrochemical sensing.
- Heater power and preheat
- Broader cross-gas response
Electrochemical, MOS and MEMS ammonia sensors solve different problems
NH₃ is measured with several sensing principles. For OEM design, the choice is usually a trade between selectivity, response, lifetime, power, cost and integration effort.
Electrochemical cell
Produces a concentration-related current from the NH₃ reaction. Common in portable and fixed toxic-gas instruments.
Best fit: quantitative industrial safety.Conditioned EC module
Adds amplification, compensation, processor and UART/analog output around the electrochemical element.
Best fit: faster OEM integration.MOS semiconductor
A heated metal-oxide layer changes resistance in NH₃. It is economical and can cover a wide range, but cross-gas response is broader.
Best fit: cost-sensitive leak / ventilation products.MEMS-MOX
Uses a micro-hotplate to reduce heater size and power while retaining metal-oxide sensing behavior.
Best fit: compact IoT and embedded products.Ammonia sensors for different OEM requirements
Compare products against the application they are designed for. A portable safety cell, a high-humidity fixed sensor, an R717 leak detector and an agricultural ventilation sensor do not use the same selection criteria.
| OEM need | Manufacturer | Model | Type | Published range | Key engineering point | Official source |
|---|---|---|---|---|---|---|
| Long-life industrial NH₃ | Winsen | UE-NH₃ | Electrochemical | 0–100 ppm | T90 ≤120 s; 5-year working-life positioning for livestock, industrial and environmental monitoring. | Official ↗ |
| General industrial / environmental | Winsen | ME4-NH₃ | Electrochemical | 0–50 ppm max 200 ppm | 0.1 ppm resolution, T90 ≤90 s; 2-year published life under 2 ppm NH₃ exposure. | Official ↗ |
| Portable / fixed safety | SENKO | SS21N8 | Electrochemical | 0–100 ppm max overload 200 ppm | T90 <30 s, >24-month life; published low cross-sensitivity to H₂S, NO₂ and H₂. | Official ↗ |
| Filtered portable safety | Alphasense | NH3-AF | Filtered electrochemical | 0–100 ppm | Filtered A-Series cell; T90 ≈300 s to 50 ppm; >24-month operating-life positioning. | Official ↗ |
| Fixed / high-humidity NH₃ | Alphasense | NH3-B1 | B-Series electrochemical | 0–100 ppm | Current Alphasense portfolio positions B1 for fixed installations, refrigerated areas and high-humidity environments. | Official ↗ |
| Refrigeration / poultry ventilation | Figaro | TGS826 | MOS semiconductor | 30–300 ppm typical detection range | Designed for ammonia leak detection in refrigeration and ventilation control in agricultural / poultry facilities. | Datasheet ↗ |
| Low-range digital environmental OEM | Winsen | ZE801-NH₃ | Electrochemical module | 0–50 ppm | UART + 0–5 V analog, T90 ≤30 s, 0.001 ppm published resolution and temperature/humidity compensation. | Official ↗ |
| Compact embedded NH₃ | Winsen | GM-802B | MEMS-MOX | 1–300 ppm | 5×5×1.55 mm package, ≤45 mW heater; used in refrigeration leak and agricultural ventilation applications. | Official ↗ |
| High-range agricultural / process | Membrapor | NH3/CR family | Electrochemical | 200 / 1,000 / 5,000 / 10,000 ppm classes | R-type high-range ammonia family for agricultural and process applications; CAL and AFE versions are also published. | Official ↗ |
| Broad Sensoric NH₃ range | Honeywell | NH3 3E family | Electrochemical | 100 / 500 ppm families and higher | Current Sensoric resource library includes NH3 3E 100 SE and NH3 3E 500 SE for industrial toxic-gas instrumentation. | Official ↗ |
Published values are manufacturer component data. Check the latest datasheet, bias requirements, cross-sensitivity and exposure-life assumptions before production.
NH₃ sensor priorities change with the installation
Industrial refrigeration and R717 leak detection
Ammonia refrigeration systems need leak detection around machinery rooms, valves, compressors and other release points. High humidity, ventilation and sensor response are part of the detector design.
| Route | Range class | Strength | Watch point |
|---|---|---|---|
| Electrochemical | 0–50 / 100 ppm | Quantitative toxic-gas measurement and low sensing-element power. | T90 can be slower than CO/H₂S cells; check overload and exposure life. |
| Figaro TGS826 MOS | 30–300 ppm | Purpose-published for refrigeration NH₃ leakage. | Heater power and broader gas response must be handled in the product design. |
| MEMS-MOX | 1–300 ppm | Compact, low heater power and simple embedded integration. | Not equivalent to a selective electrochemical safety channel. |
Portable and fixed industrial safety
For worker protection, concentration accuracy and the real alarm response are more important than the largest available range.
| Model | Range | T90 | Engineering point |
|---|---|---|---|
| SENKO SS21N8 | 0–100 ppm | <30 s | Fast electrochemical route with published low cross-sensitivity. |
| Winsen ME4-NH₃ | 0–50 ppm | ≤90 s | 32 mm EC cell; 0.1 ppm resolution and defined 2 ppm exposure-life condition. |
| Alphasense NH3-AF | 0–100 ppm | ≈300 s | Filtered A-Series route; response speed must be checked against the alarm requirement. |
Livestock and poultry ventilation
Ammonia in barns changes with manure condition, temperature, stocking density and ventilation. A stable low-level trend can be more useful than a very wide range.
| Sensor route | Why it fits | Design check |
|---|---|---|
| Fixed electrochemical | Better quantitative tracking when the target is low-tens-of-ppm control. | High humidity, condensation and lifetime under chronic NH₃ exposure. |
| Figaro TGS826 | Officially positioned for agricultural and poultry ventilation control. | 833 mW heater power and calibration against site background gases. |
| Winsen GM-802B | Compact MEMS route with ≤45 mW heater. | Cross-gas behavior and long-term drift in barn environments. |
High-range ammonia
Fertilizer, agricultural and process applications can exceed the normal 50–100 ppm toxic-safety range. Use a sensor designed for sustained high concentration rather than repeatedly overloading a low-range cell.
| Manufacturer / family | Range class | Application point | Official source |
|---|---|---|---|
| Membrapor NH3/CR-200 | 200 ppm | High-range compact R-type electrochemical route. | Official ↗ |
| Membrapor NH3/CR-1000 | 1,000 ppm | Agricultural / process concentration measurement. | Official ↗ |
| Membrapor NH3/CR-5000 | 5,000 ppm | High concentration where conventional safety cells would be overloaded. | Official ↗ |
| Membrapor NH3/CR-10000 | 10,000 ppm | Very high-range route; evaluate a dedicated process analyzer where continuous accuracy is critical. | Official ↗ |
What usually causes ammonia measurement problems
Response time
NH₃ electrochemical sensors can be slower than engineers expect from CO or H₂S designs. The sensor T90 must be checked against the actual alarm or ventilation-control requirement.
- Compare sensor T90 at the concentration used in the datasheet.
- Add enclosure diffusion, filters, tubing, pumps and firmware averaging to estimate total system response.
- Do not compensate a slow physical response with an aggressive software alarm threshold without validation.
Water and sample-line loss
Ammonia is highly soluble in water. Wet tubing, condensation and water films can delay NH₃ reaching the sensor and can reduce the concentration delivered to the cell.
- Keep pumped sample lines short and dry.
- Use tubing and fittings validated for NH₃ service.
- In refrigeration and livestock sites, design for condensation control rather than relying only on the sensor RH specification.
Cumulative exposure
Ammonia electrochemical lifetime is strongly tied to concentration and exposure history. A life statement measured around a low NH₃ background should not be applied to a site with frequent high-level releases.
- Read the concentration condition attached to the manufacturer's life figure.
- Use a high-range sensor where elevated NH₃ is routine, not an upset.
- Track calibration drift in continuously exposed agricultural and process locations.
Cross-sensitivity
NH₃ cells and MOS sensors can respond to other gases. Relevant interferents may include H₂S, amines, alcohols, NO₂, H₂ and process vapors.
- Use the exact model's cross-sensitivity data.
- Filtered electrochemical variants can reduce some interferents.
- MOS and MEMS products need application-specific calibration because their gas response is intentionally broader.
Sensor placement is part of the ammonia leak-detection design
A sensor with good laboratory data can still perform poorly if the installation does not expose it to the leak plume. Machinery-room airflow, exhaust fans, compressors, valves, ceilings and local obstructions change where NH₃ reaches the detector.
Map release points
Compressors, valve stations, receivers, evaporators and service connections.
Review airflow
Use actual ventilation direction and room geometry, not gas density alone.
Set alarm ranges
Match the detector range to ventilation, alarm and emergency actions.
Test the installed path
Verify gas reaches the sensor under realistic fan and equipment conditions.
Ventilation control needs stable trends, not just alarm detection
In livestock housing, NH₃ is generated continuously from manure and urine. The useful sensor is one that can track the occupied-zone concentration over changing humidity, temperature and airflow.
What to optimize
- Low-tens-of-ppm measurement stability.
- Humidity compensation and non-condensing installation.
- Service interval under chronic NH₃ exposure.
- Representative placement at animal breathing height and ventilation zones.
What to avoid
- Mounting directly in wet washdown or condensation paths.
- Using one point to represent a large building with uneven airflow.
- Treating a broad MOS response as calibrated NH₃ concentration without site validation.
- Ignoring sensor drift when NH₃ is continuously present.
Raw NH₃ sensor, module, MOS or MEMS?
Choose electrochemical when:
- The product needs quantitative toxic-gas concentration.
- Low sensing-element power is important.
- You can support calibration, AFE and replacement planning.
- Cross-sensitivity data and application standards matter.
Choose MOS / MEMS when:
- Cost, small size or simple embedded hardware is the priority.
- Heater power and preheat are acceptable.
- The application can be calibrated around broader gas response.
- You do not need electrochemical-style selectivity as the only safety channel.
Additional Winsen ammonia sensors and modules
These products cover electrochemical, semiconductor, MEMS and conditioned-module routes. Select them by output, range, heater power and the measurement task rather than by package alone.
UE-NH₃
0–100 ppm long-life electrochemical sensor, T90 ≤120 s. Positioned for livestock, industrial and environmental NH₃ monitoring.
ME4-NH₃
0–50 ppm, max 200 ppm, 0.1 ppm resolution and T90 ≤90 s. Published life is 2 years under 2 ppm NH₃ exposure.
ME3-NH₃
0–100 ppm, max 200 ppm, 0.5 ppm resolution and T90 ≤60 s in a smaller electrochemical package.
ZE03-NH₃ configuration
General toxic-gas module with UART and analog voltage output. The current ZE03 product page directs designers to the gas-specific manual for final measurement range.
ZE801-NH₃
0–50 ppm electrochemical module with UART and 0–5 V analog output, T90 ≤30 s, temperature/humidity compensation and optional pump integration.
MQ137
5–500 ppm SnO₂ semiconductor sensor. Heater consumption ≤950 mW and published preheat time is over 48 hours. It also responds to organic amines.
MP-702
0–100 ppm planar MOS ammonia sensor with ≤300 mW heater consumption. Published applications include refrigerators, cold storage and agricultural breeding.
GM-802B
1–300 ppm MEMS ammonia sensor in a 5×5×1.55 mm package, with ≤45 mW heater consumption. Used for refrigeration leakage and agricultural ventilation.
Other ammonia sensor product ranges
These manufacturers publish NH₃ sensors for refrigeration, portable safety, fixed monitoring, agriculture and high-range process measurement.
Alphasense
A-Series portable and B-Series fixed/high-humidity electrochemical NH₃ sensors.
Honeywell Sensoric
Industrial NH₃ 3E sensor families covering multiple concentration ranges.
SENKO
Fast-response electrochemical NH₃ sensor for refrigeration and industrial safety.
Figaro Engineering
MOS ammonia sensing for refrigeration leakage and agricultural ventilation.
Membrapor
Compact and miniature electrochemical NH₃ sensors up to 10,000 ppm class, including CAL/AFE versions.
Submit an NH₃ sensor
Manufacturers can provide an official product page and current datasheet for inclusion.
NH₃ sensor life depends on how much ammonia it actually sees
A published two-year or five-year life is meaningful only with the exposure conditions behind that figure. Refrigeration rooms with rare leaks and livestock buildings with continuous background NH₃ can age the same sensor very differently.
Exposure history
Track repeated high-level events and chronic background concentration. Electrochemical NH₃ sensor life can be exposure-limited.
Bump test
Confirms that NH₃ reaches the detector and the channel responds. It does not establish measurement accuracy.
Calibration
Use NH₃ calibration gas and a gas path validated for reactive ammonia. Allow enough stabilization time for the selected sensor.
Ammonia sensor questions
What NH₃ sensor range should I use for an ammonia refrigeration system?
For room or machinery-space leak detection, low-hundreds-ppm electrochemical sensors are common starting points, while process or severe-leak monitoring may require a much wider range. The correct range must follow the alarm strategy, ventilation design, applicable refrigeration standard and credible release scenario.
Why can electrochemical ammonia sensors respond more slowly than CO or H₂S sensors?
Ammonia electrochemical chemistry and diffusion design are different, and some cells deliberately trade response speed for life, selectivity or stability. Published T90 values can range from tens of seconds to several minutes, so the exact model should be matched to the alarm requirement.
Can I use an NH₃ gas sensor in a high-humidity livestock house?
Yes, if the sensor is rated for the expected humidity and condensation is prevented. Fixed agricultural monitoring also needs careful placement because ammonia distribution changes with ventilation, temperature, litter/manure conditions and animal activity.
Why does sample tubing matter for ammonia measurement?
Ammonia is highly soluble in water and can interact with wet surfaces. Long or damp sampling lines can delay or reduce the gas concentration reaching the sensor. Keep the sample path short, dry and made from materials validated for NH3.
Should I choose an electrochemical, MOS or MEMS ammonia sensor?
Electrochemical sensors are commonly used for quantitative toxic-gas safety measurement. MOS and MEMS-MOX sensors can offer lower cost, smaller size or wider response range, but they require heater power and usually have broader cross-gas response. The technologies should be evaluated as different design routes, not direct substitutes.
What is the difference between a raw NH₃ sensor and a module?
A raw element needs an analog front end, compensation and calibration designed by the OEM. A module adds signal conditioning and may provide UART or analog output, reducing integration time but increasing size and unit cost.
How does continuous ammonia exposure affect sensor life?
Electrochemical ammonia life depends strongly on concentration and cumulative exposure. A sensor published for multi-year service in low background NH3 may age faster in a location with repeated high-level leaks or sustained exposure. Use the manufacturer's exposure assumptions when estimating replacement intervals.
How should ammonia sensors be calibrated?
Use a certified NH3 calibration gas at the concentration and flow method specified for the instrument. Minimize reactive-gas losses in regulators, tubing and fittings, allow the sensor enough stabilization time, and distinguish routine bump testing from full span calibration.
Final checks before design freeze
Validate the complete detector with the expected NH₃ concentration, humidity, airflow and sample path. The sensor datasheet is the component starting point, not the finished-system specification.
- Confirm range, overload and T90 against the alarm or ventilation-control requirement.
- Review the exact cross-sensitivity table and bias requirements.
- Keep condensation and wet sampling surfaces away from the NH₃ gas path.
- Account for cumulative NH₃ exposure when estimating sensor life.
- Validate tubing, regulators and calibration flow for reactive ammonia gas.
- Confirm the applicable refrigeration, industrial-safety or environmental requirements for the final product.
Need an NH₃ sensor for an OEM project?
Send the target range, refrigeration or industrial application, operating environment, response requirement, output interface and product format. Manufacturers can also submit ammonia sensor models with an official product page and current datasheet.
Specifications and product availability can change. Confirm the latest manufacturer datasheet before engineering, compliance or purchasing decisions.