Laser Gas Analyzers

TDLAS analyzers with leading market share worldwide

Laser gas analyzers are tools that use lasers diodes to analyze gas absorption, with TDLAS representing tunable diode laser absorption spectroscopy.

The analyzers work on the principle that irradiating exhaust gas, chimneys, or the like with a near-infrared laser tuned to a specific wavelength causes the laser to be absorbed by certain molecules. Applying this principle lets users detect and monitor oxygen, carbon dioxide, methane, ammonia, hydrogen chloride, and other gases. Direct gas measurement without sampling also provides a means of non-contact measurement without any special preparation such as changing the temperature. This also enables measurement of dihydrogen, which was difficult using conventional technology.

Highlights

Essentially maintenance-free; only O-rings need replacement
Products sold in 1998 are still in operation.
No zero/span drift, in principle
Responsive: measures within 2 sec.
Enables early detection if tolerance is exceeded, and prompt process control and safety management.
Site-specific flange connections and sampling methods can be proposed
No special preparation required—direct measurement of raw gas, even under harsh conditions
Can be used in environments with high temperatures, dust, saturation, mist, or corrosive/toxic gas.
Accurate measurement without interference by coexisting gases
Offers advantages from the standpoint of lower limit, accuracy, and the range of gases that can be measured.
Models available that meet domestic explosion proof guidelines

Specifications

Specifications	Max. meas. length (pipe inner diameter)：20 m Response time　：Approx. 2 sec. or less Span drift　　　：Not exceeding 4 % of measurable range Zero drift　　　：Not exceeding 2 % of measurable range
Environmental conditions	Ambient temp.　：-20 °C to 55 °C (optionally up to 65 °C) Storage temp.　：-20 °C to 55 °C Protection rating：IP66
Inputs/outputs	Analog output 　　　　：4–20 mA (concentration/transmittance) Digital output (optional) ：TCP/IP, Modbus, fiber optic Relay output 　　　　　：Alarm relay (minor failure), error relay (major failure) Analog input 　　　　　：4–20 mA (temp./pressure output available)
Power specifications	Power supply　　　：100 VAC, 50/60 Hz Power consumption ：Max. 20 W 4–20 mA output 　　：Max. 500 Ohms (isolated) Relay output　　　　：1 A at 30 VDC/AC
Laser class	Laser class：Class 1 CE　　　　：Certified EMC　　　：2014/30/EU compliant
Explosion-proof compliance	Domestic explosion-proof guidelines (zone 1, 2)：Ex in nA nC IIC T4/T5 Gc, Ex tc IIIC T100 °C Dc
Installation	Flange diameter：ANSI 2 in./150 lbs. (equivalent to JIS 10K 50A) Other diameters available on request (parallel within 1.5°) Purging　　：N2 or air purging Purge flow　：30–100 l/min. (depending on gas conditions)
Maintenance	Annual calibration recommended
Dimensions/weight	Transmitter　　　　　　　　　：428 × 266 × 166 mm, 7 kg Transmitter (explosion-proof) ：405 × 270 × 310 mm, 8 kg Receiving unit　　　　　　　　：355 × 125 × 125 mm, 3.9 kg

Principle

The analyzers employ near-infrared single-line absorption spectroscopy using a diode laser as a light source.
Each molecule has its own frequency, which causes laser light of the same frequency to resonate with the molecule, and in turn, absorb (attenuate) the light energy.

Applications

Combustion improvement：
　Measurement of high-temperature gases (O2, CO, etc.) at the outlet of incinerators for heating, melting, or combustion furnaces, etc.
Quality control：
　Measurement of impurities or by-products in process gases on production lines (NH3, H2O, HCL, etc.)
Air pollution monitoring：
　Measurement of low concentrations in biomass exhaust gas (NH3, HCL, HF, CO2, etc.)
Explosion prevention：
　Constant monitoring (of O2, CO, etc.) to prevent explosion

Structural Diagram

As instruments that measure gas concentration, these products essentially consist of a light transmitter incorporating a diode laser and a receiver incorporating a photodetector. Both parts feature air purging and optical axis alignment functions. The transmitter incorporates an LCD screen that shows measured gas concentration, laser transmittance, and any error messages in the event of malfunction.