The "detection method" of ammonia (NH3) gas detector depends on the specific application scenario, detection purpose, budget, and requirements for performance (such as accuracy, response speed, stability). At present, the mainstream detection technologies in the market have their own advantages and disadvantages.

The following is a detailed comparison of several core detection technologies, as well as a guide on how to choose methods based on needs.

1、 Principles and Comparison of Mainstream Detection Technologies

The working principle, advantages, disadvantages, and applicable scenarios of detection technology

Electrochemical sensor: Ammonia undergoes oxidation-reduction reaction inside the sensor, producing a current proportional to the gas concentration. Low cost, low power consumption, good portability, and good selectivity for ammonia gas. Short lifespan (usually 1-3 years), easily affected by temperature and humidity, may be subject to cross interference from other gases (such as amines), and requires regular calibration. Portable inspection device, personal protective alarm, small ventilation control system. Suitable for safety monitoring and leak investigation.

Semiconductor sensors adsorb ammonia on the surface of metal oxides, changing their resistance values. Low cost, long lifespan (up to 5-10 years), simple structure, and small size. Poor selectivity (susceptible to interference from multiple VOCs), non-linear output, significant environmental impact, and baseline drift. Low cost home alarm and fan linkage control. Not suitable for precise measurement.

Infrared (NDIR) sensors calculate concentration by measuring the attenuation of light intensity based on the absorption of specific wavelengths of infrared light by ammonia gas. High precision, good selectivity, long lifespan (>5 years), not affected by temperature and humidity interference, no need for oxygen, fast response. High cost, relatively large sensor volume, and possible impact of optical window contamination. Industrial process control, online environmental monitoring, and agricultural breeding facilities. Suitable for fixed monitoring that requires high reliability and long-term stability.

Photoionization (PID) sensors use ultraviolet lamps to ionize gas molecules and measure ion current. Sensitivity (ppb level), fast response, and ability to detect various VOCs. Unable to specifically recognize ammonia, the response coefficient to ammonia needs to be calibrated separately, expensive, and the lamp source has a lifespan. Mainly used for detecting volatile organic compounds. Measuring ammonia is not only considered when sensitivity is required and there are few known interfering gases.

Laser absorption spectroscopy (TDLAS) uses a tunable laser to scan a single fine absorption line of ammonia gas. Ultra high precision and selectivity, extremely fast response, capable of in-situ measurement, no lag, low maintenance. The equipment is very expensive, technically complex, and usually a system level device. Scientific research, strict emission monitoring (such as flue gas emission monitoring system), and atmospheric background stations. Scenarios that pursue performance.

2、 How to choose a 'good' detection method? ——Scenario based Guide

1. Life safety and leakage inspection

·Requirement: Fast response, portable, and reliable alarm.

·Portable electrochemical gas detector.

·Reason: High cost-effectiveness, optimized for ammonia gas, able to provide sound and light vibration alarm, suitable for staff to carry into risk areas.

2. Industrial process monitoring and environmental emissions

·Requirement: Continuous, precise, stable, and requiring minimal maintenance.

Fixed online infrared (NDIR) gas detector.

·Reason: Good long-term stability, strong anti-interference ability, reliable data, in line with environmental monitoring requirements. For ultra-high precision requirements (such as chimney emissions), the TDLAS system is chosen.

3. Agricultural breeding (livestock and poultry houses, greenhouses)

·Requirement: Continuous monitoring, controlled ventilation, humid environment, presence of multiple gases.

·Fixed infrared (NDIR) detector or high-performance anti-interference electrochemical detector.

·Reason: NDIR is not affected by high humidity and background gases. If the budget is limited, an electrochemical sensor specially optimized for agricultural environments can be chosen.

4. Indoor air quality and smart homes

·Requirement: Low cost, linkage control.

Semiconductor sensors.

·Reason: The price is advantageous and can be integrated into fresh air systems or smart homes to trigger exhaust fans. But the data is only for trend reference.

5. Emergency response and broad-spectrum screening

·Requirement: Quickly understand the overall situation of various harmful gases on site.

·Select: PID detector.

·Reason: Although not specifically designed for ammonia, it can quickly detect various VOCs leaks, including ammonia, and is a commonly used equipment for emergency personnel. Attention should be paid to the response coefficient of ammonia gas.

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3、 Core selection and usage suggestions

1. Clear range: Agriculture and safety monitoring usually range from 0-100 ppm; Industrial leak detection is 0-500 ppm; Process control and emission monitoring may require 0-5000 ppm or even percentage levels.

2. Focus on key indicators:

·Resolution: The minimum concentration unit displayed (such as 0.1ppm or 1ppm).

·Response time (T90): Usually requires<60 seconds, the faster the better.

·Accuracy: ± percentage of reading, the higher the better.

3. Safety certification: Ensure that the instrument has the necessary explosion-proof certification (such as ATEX, UL, for use in hazardous areas) and type approval certificate (CPA) for measuring instruments.

4. Maintenance and Calibration:

·Regular calibration: All sensors must be calibrated regularly (usually every 3-6 months) using standard gases to ensure accuracy.

·Sensor lifespan: Understand the expected replacement cycle and cost of core sensors.