Non-Dispersive Infrared Method
Stationary sensor
Sensor: DE
Example: IRF-1301

Stationary sensor
Example: DE-3315-1

1. Brief description

Portable sensor
Example: DE-3123-1

Category

Based on the fact that many gases absorb infrared rays, this sensor applies infrared light to themeasurement cell to detect changes in infrared light caused by the absorption of a detectable gas.
It seamlessly detects all infrared light in a particular wavelength range without separating(dispersing) infrared light on a wavelength basis.

Detectable gasCombustible

OpticalToxic

2. Structure and principles[Structure][Structure]

This sensor is structured with an infrared light source and an infrared
sensor, between which a measurement cell and an optical filter areplaced. The infrared light source emits infrared light, which passes
through the measurement cell and optical filter to be detected by theinfrared sensor. The optical filter selectively allows the infrared
wavelengths that the appropriate detectable gas absorbs to passthrough it.

Gas release

Detectable gas
Optical filter

Infrared lightA detectable gas enters the measurement cell and absorbs infrared light.
This reduces the amount of infrared light detected by the infraredsensor. Some detectable gases where the concentrations are known
are entered to determine the relationship (calibration curve) between
the decrease in infrared light amount and the concentration of eachdetectable gas. When a detectable gas where the concentration isunknown is entered, the sensor uses the calibration curve based on themeasured decrease in infrared light amount to determine the gas
concentration.

Measurement
cell

Infrared lightsource[Principles]

Infrared sensor[Calibration curve (example)]
Decrease in
infrared light0

Detectable-gas concentration

3. Features (of the sensor DE-3313-5 as an example)○ Output characteristics○ Aging characteristics

100

i-C4H10Outputratio

The gas concentration andsensor output are not in
proportional to each other but
in a relationship as shown by
the curve in the right figure.
(i-C4H10: isobutane)(%)

01000Concentration (%LEL)○ Responsiveness70(%LEL)

N2

N200Time (min.)○ Temperature and humiditycharacteristics

100

By performing temperature corrections,i-C4H10
you can minimize the dependency of50%LEL
readings on temperature within thespecified temperature range.
N2
When no condensation has formed (%LEL)
0inside the gas cell, the sensor is-20
almost not affected by humidity.
Reading

Reading

When gas is supplied to thegas sensor at a constant flow
rate, the sensor excellently
reproduces responses.

i-C4H10
50%LELIn an environment with small variations in temperature, thesensor remains stable without showing large deteriorationin reading accuracy over time. Depending on theenvironment, the sensor may significantly deteriorate overtime. If this is the case, you can minimize the deterioration
by performing gas calibration every six months or so.

350Temperature (℃)

4. Detectable gas, molecular formula, model, and detection
range (examples)
Detectable gas

Molecularformula

Detection
range

Model #

Carbon dioxide

CO2IRR-0409

0-5vol%Carbon dioxide

CO2IRR-0433

0-10000ppm

Methane

CH4IRF-1301

0-100%LEL

HFC-134a

C2H2F4DE-2113-35

0-5000 ppm

Methane tetrafluoride

CF4DE-2113-42

Sulfur hexafluoride

SF6DE-2113-43

0-500 ppm

5. Products of this type (examples)○Stationary products... SD-3RI, SD-3DRI, SD-1RI, SDWL-1RI,
RI-600, GD-70D, RI-257○Portable products... GX-3R Pro, RX-8000,RX-8500, RX-8700,
RI-557
SD-3RI