Avoiding moisture build up within the optics of NDIR Sensors.

condensation-build-up-NDIR-sensors

How Does Dynament NDIR Optimise Energy Efficiency and Prevent Condensation?

Dynament sensors are available in two power variants: a regular-power sensor suitable for everyday environments, which operates 7-8°C above ambient temperature, and a high-power version designed for extreme environments, such as freezers, which increases to 20°C above ambient. Both sensor types are inherently more resistant to the onset of condensation, but they can still be affected under certain conditions. It is essential to ensure that the sensor surface temperatures remain above the dew point; otherwise, water will condense on the optical surfaces, compromising the NDIR sensor's accuracy and performance.

Mounting the sensor in a manner that protects it from rapid temperature changes, drying the gas sample before introducing it to the sensor, and running the sensor at the 5V maximum power input can all contribute to keeping your Dynament NDIR sensor condensation-free.

Why is it essential to avoid moisture in NDIR Sensors

  • Interference with Measurements:
  • Moisture can cause significant interference in the readings of NDIR sensors. If condensation can form within the sensor optics, it can change the amount of energy the pyroelectric device receives. This condensation interference can mislead the sensor into detecting gas when, in fact, it is moisture.

  • Reduced Sensor Sensitivity:
  • When water vapor accumulates on optical surfaces, it scatters light, diminishing the intensity of the signal that reaches the detector. This effect can lead to erroneous gas readings. Additionally, condensation can leave behind debris and contamination, further affecting the long-term performance of the sensor.

  • Corrosion and Damage:
  • Prolonged exposure to moisture can lead to degradation of optical surfaces. If moisture combines with hydrogen sulphide, sulphuric acid is formed, which can permanently damage the optical path. This not only impacts performance but can also result in premature sensor failure. Protecting the integrity of the sensor components is crucial for ensuring longevity and reducing maintenance costs.

    dynament-sensors-png

    What is condensation?

    Condensation occurs when water vapor in the air or gas settles on solid surfaces that are cooler than the surrounding atmosphere. When moist air or gas containing water vapor comes into contact with a cold, impervious surface, some of this moisture is released as water droplets, resulting in condensation.

    The dew point is the temperature at which moist air or gas becomes saturated with water vapor, the gaseous form of water. When the gas reaches this dew point at a given pressure, the water vapor is in equilibrium with liquid water, meaning the rate of condensation matches the rate of evaporation. Consequently, when the temperature falls below the dew point, liquid water begins to condense on solid surfaces.

    What are NDIR Sensors?

    Dynament infrared sensors utilize the NDIR principle to detect the presence of specific gases.

    Each sensor features a long-lasting tungsten filament infrared light source, an optical cavity where gas diffuses, temperature-compensated pyroelectric infrared detectors, an integrated semiconductor temperature sensor, and electronics designed to process signals from the pyroelectric detector.

    The sensor incorporates an infrared lamp that pulses to produce a sinusoidal signal from the detector and the reference channels. As the target gas enters the sensor, the sinusoidal signal from the detector decreases in amplitude while the reference signal remains constant. Gas concentration is determined by measuring the difference in the ratio of the detector and reference signals in both zero gas and in the presence of the target gas. The reference signal helps adjust the gas readings for factors such as temperature variations and lamp aging, which leads to better long-term stability.

    For more information on the range of sensors available from Dynament or for any technical assistance, please contact us at sensors@processsensing.com where our team will be happy to help.




    < Back to Knowledge Base