Introduction
The 3.3V laser methane sensor is developed based on the tunable
laser gas absorption spectroscopy (TD-LAS), which uses 1653.7nm
laser to detect methane gas by characteristic "fingerprint
spectrum" absorption, and is resistant to water vapor or other gas
interference. Based on the combination of direct absorption and
wavelength modulation absorption spectroscopy technology, and the
"N" type optical path structure design, long absorption optical
path, high detection sensitivity and precision; Choose the low
temperature performance of laser and photoelectric detector devices
and temperature compensation correction algorithm with wide
temperature, environmental adaptability is strong; Standard thread
installation interface and standard communication protocol design,
strong commonality.
As the core component of methane gas monitor, the product can be
widely used in underground space, catering industry, industrial
chemical industry and coal mine and other fields of methane gas
leakage detection alarm.
Feature
• High detection accuracy
Direct and wavelength modulation technology combined with folded
optical path design, measurement error ≤±6% true value @25℃
• Good environmental adaptability
Wide temperature compensation correction algorithm, can meet
-40~+70℃ application
• Strong anti-interference
Methane "fingerprint spectrum" laser absorption detection
technology, anti-poisoning, anti-water vapor and other gas
interference;
• Strong structural protection
Stainless steel material design, meets the explosion-proof level
Exia IIC T6 Ga
• Low cost
Long service life, low power consumption, modular design, easy to
integrate
Dimensions
Technical Parameters:
| Parameters | Technical Indicators |
| Measuring gas | Methane |
| Measuring principle | TD-LAS |
| Detection mode | Dispersive |
| Measuring range | 0-20% VOL (customizable) |
| Measurement error @25℃ | <+0.06%VOL,0-1%VOL
<+6%True value,1-20% VOL |
| Lower detection limit | 0.2% VOL |
| Minimum resolution | 0.01% VOL |
| Response time | T90<15s |
| Operating voltage | 3.0VDC ~3.6VDC |
| Average operating current | <30mA |
| Peak current | <210mA |
| Output mode | Standard TTL serial port |
| Operating temperature | -40℃~ +70℃ |
| Operating humidity | 0 ~ 99% RH (condensation) |
| Explosion proof sign | Ex ia IICT6 Ga |
| Intrinsic safety parameter | Ui:3.3V Ii:50mA
Pi:0.250W Ci:20uF
Li:3.14uH |
| Protection degree | IP66 |
| Product weight | 255g |
| Products dimensions | φ41.7mmx63.6mm |
Applications:
a) The sensor continuously outputs the measured methane
concentration, measured temperature, measured pressure, laser
signal strength, laser operating temperature and fault code through
the standard TTL serial port
b) It has a self-test function, which can detect whether the laser,
photoelectric detector and voltage stabilization sensor are normal,
which helps to eliminate the fault point.
Communication Interface and Definition
Interface form: SH1.0mm/4P
Cable length: 200mm
| Number | Color | Interface definition |
| 1 | Red | VCC |
| 2 | Black | GND |
| 3 | Blue | RX |
| 4 | Green | TX |
Communication Protocol
(1) Communication interface configuration
UART serial port: Baud rate: 115200, data bits: 8 bits,
Stop bit: 1 bit, parity bit: no check
(2) Description of communication protocol
| Byte sequence number | Function code | Byte number | Unit | Example |
| 0 | Head of frame | 1 | - | A |
| 1-7 | Concentration | 7 | %VOL | +000.00 |
| 8 | Blank space | 1 | - | <SP> |
| 9-13 | Ambient temperature | 5 | ℃ | +23.7 |
| 14 | Blank space | 1 | - | <SP> |
| 15-21 | Ambient air pressure | 7 | hPa | 1006.22 |
| 22 | Blank space | 1 | - | <SP> |
| 23-27 | Intensity of light | 5 | - | +16.1 |
| 28 | Blank space | 1 | - | <SP> |
| 29-35 | Gain coefficient | 7 | - | B+6.0 |
| 36 | Blank space | 1 | - | <SP> |
| 37-38 | Fault code | 2 | - | 00 |
| 39 | Blank space | 1 | - | <SP> |
| 40-41 | Xor check code | 2 | - | 3D |
| 42 | Carriage return character | 1 | <CR>: | <CR>: |
| 43 | Line break character | 1 | <LF> | <LF> |
After the sensor is powered on, it goes through a period of
preprocessing (6-10s) and then begins to periodically (1Hz) output
a fixed-length string. The string format is shown in the figure
above.
Output string parsing (sample):
A 000.00 + 24.0 + 1006.22 + 16.1 + 006.0 B 00 13
A: the frame head;
+000.00: methane concentration value, two decimal places reserved,
unit %vol;
+ 24.0: the environment temperature, the unit ℃;
1006.22: the environment pressure, the unit hPa;
16.1: the laser light intensity and effective range 3.6 21.6;
006.0: magnification factor, normal range 1.0-126.0;
00: fault codes
01: abnormal optical signal; 02; Ambient temperature or abnormal
pressure; Optical signal is too strong; 04 laser temperature
anomaly;
05: light signal is too weak;
13: xor check code
Fault Code
| Fault code | Meaning | Fault code | Meaning |
| 0 | Sensor working properly | 3 | The laser signal is strong |
| 1 | The photodetector signal is abnormal | 4 | Laser temperature anomaly |
| 2 | Temperature and pressure sensor abnormal | 5 | The laser signal is too weak |
Precautions
a) The working voltage of the sensor is 3.3V, and the serial
interface level is 3.3V;
b) sensor contains precision optical components, please avoid
violent collision;
c) Working environment conditions: -40℃ ~ +70℃
d) Relative humidity 0-99% RH (non-condensation).
Note: The working voltage of the sensor is 3.3V. It is forbidden to
connect the power supply voltage exceeding 3.6VDC to the sensor to
avoid damage to the sensor.
Support and Services:
The Gas Detector Sensor product technical support and services
include:
Expert technical assistance for troubleshooting and problem-solving
Repair and maintenance services
Calibration and testing services to ensure accurate readings
Product documentation and manuals
Assistance with product selection and customization
Our goal is to ensure that our customers receive the highest level
of support and service to keep their gas detector sensors working
efficiently and effectively.
Packing and Shipping:
Product Packaging:
Gas Detector Sensor unit
User manual
Mounting hardware
Calibration certificate
Shipping Information:
Expected delivery time: 5-8 business days
