Explosion-proof Gas Sampling System

The Explosion-proof Gas Sampling System is used in the gas analysis industry. Its main principle is to sample flue gas or high-temperature, high-humidity gas from the field, then cool, dehumidify, filter dust and tar, and maintain the temperature and humidity of the gas within a specific range, enabling the gas analyzer to detect concentrations correctly. The entire process is automated and requires no human intervention.

The Gas Sampling System is suitable for situations where the gas sample contains relatively little dust but is at high temperature and humidity. For situations with higher dust and tar levels, a separate tar treatment system is required. It features a 28MFlash memory for storing large amounts of data and supports exporting historical data and alarm data to a USB drive, facilitating subsequent data analysis.

★★★★★

  • Short delivery time
  • Better price
  • Customizable parameters

Features

  • High-temperature pretreatment device: Ensures effective condensation and dehydration of the gas;
  • Three-stage filtration device: Removes oil, dust, and dries;
  • Temperature monitoring device: Real-time temperature display;
  • Gas sampling device: 5-liter vacuum sampling pump;
  • Gas detection device: Monitors toxic and harmful gases and other industrial waste gases;
  • Built-in electronic condenser and drain pump for automatic discharge of condensate;
  • Flow control device: Controls real-time gas flow;
  • PLC control system: Data analysis, data storage, and data export;
  • 7-inch LCD touchscreen display: Gas unit switching;
  • Optional: Wireless transmission module (4G, LoRa, Wi-Fi, DTU, etc.) for data upload;
  • Waterproof design, fast, reliable, and stable detection;
  • The gas analyzer can be built into the chassis or externally mounted;
  • Standard sampling distance is 20 meters, with optional maximum sampling distance exceeding 40 meters;
  • Standard processing temperature is 200°C, capable of handling flue gas up to 1300°C.

Specifications

Sensor Type:Electrochemical, PID photoionization, infrared, catalytic combustion, etc.
Gas Type:Toxic and harmful waste gases and flue gas
Sampling MethodPump-suction type
Explosion-proof RatingBT4\CT6 (customizable)
Gas RangeDifferent gases have different flow ranges; (Contact customer service for more ranges)
Accuracy≤±3%FS
Resolution0.01%LEL, 0.01mg/m3, 0.01PPM, etc.
Repeatability≤±2%FS
Zero Drift≤±2%FS/6h
Span Drift≤±3%FS/6h
Response TimeT90≤3 S
Communication Method4-20mA/RS485 digital signal, switch control signal.
Operating Power35-40W
Input Power SupplyAC220V
Output Power SupplyDC24V
Operating Environment-40℃~+70℃, ≤95%RH
Measurement Unitppm, ppb, %LEL, %VOL, mg/m3, mg/L, g/m3, ug/m3, %rh, ℃, MPa, KPa, Pa, etc.
Installation MethodWall-mounted
Constant Temperature25℃: Temperature after gas treatment, settable;
Constant Humidity70%RH: Humidity after gas treatment;
Automatic DrainageAutomatic drainage based on site moisture levels;
System HeatingOptional feature to prevent pipeline freezing in extremely cold regions;
Sampling DistanceThe standard sampling distance is 20 meters; with an optional high-power vacuum pump, the sampling distance can exceed 40 meters. If the pressure of the gas being measured is high, the sampling distance should be correspondingly longer.
Sampling Flow Rate4 liters/minute (standard).
Dimensions700mm (H) x 500mm (W) x 270mm (D)
Explosion-proof Gas Sampling System Custom Configuration

Explosion-proof Gas Sampling System Applications

Explosion-proof pretreatment monitoring systems are used in various high-temperature, high-humidity, or high-dust environments. High-dust environments require an automatic backflushing system; otherwise, manual maintenance and cleaning of the dust filter are necessary.

Applications include:

  • Desulfurization and denitrification, natural gas pipelines;
  • Flue gas emissions, boiler exhaust gas;
  • Wastewater pipeline gas detection and analysis;
  • Pretreatment of flammable and explosive gas samples;
  • Sampling, purification, and environmental emission control of flue gas, exhaust gas, waste gas, and other gases from combustion equipment such as boilers, heating furnaces, kilns, incinerators, and coke ovens.
  • Suitable for use in high-temperature or low-temperature environments such as agricultural greenhouses, laboratories, cold storage facilities, and high-temperature furnaces.

Operation of the Explosion-Proof Gas Monitoring Pretreatment System:

The system processes the sample gas according to the analyzer’s acceptable pressure, temperature, humidity, flow rate, dust content, and cleanliness level. The main tasks include:

  • Sample Sampling: The sample gas is extracted from the pipeline environment using a vacuum sampling pump or a DC brushless pump;
  • Dust Filtration: The gas to be tested passes through a precision dust filter before entering the sampling pipeline. For high-dust environments, an automatic backflushing system is required;
  • Cooling Treatment: Cooling is achieved through the sampling probe and sampling pipeline, capable of handling gases up to 2000℃;
  • Heating Function: Heating and insulation to prevent water vapor condensation and partial gas dissolution in water (optional);
  • Gas-Water Separation: After the sample gas is cooled through the sampling pipeline, free water appears. The gas-water separator automatically separates the gas, water, and residual dust. Drainage;
  • Molecular sieve filtration: Filters gas to ensure sensor detection;
  • Secondary filtration: Optional based on site humidity, performs secondary water vapor separation;
  • Signal acquisition: The sensor reacts with the gas being measured, detects the gas signal, amplifies and analyzes it; the concentration of various gas components is determined;
  • Detection and analysis: Real-time detection and display of concentration, transmitting data via 4-20mA/RS485 signals, or wirelessly or via network to a remote server, environmental protection bureau, or monitoring station;
  • Flow regulation: Controls the gas intake (optional).
Exhaust gas sampling probe

Precautions for Use and Debugging

  1. Flow Control:

During system operation, the gas flow rate through the detector should be controlled to approximately 500 ml/min by adjusting the throttle valve on the flow meter and the drain pipe at the bottom of the condenser. The flow meter’s flow rate should be checked periodically to ensure it remains within the normal range.

  1. Analog Signal Output:

The detector has a 4-20mA analog signal. The 4-20mA output signal is already connected to the terminal block. The positive signal is marked with a wire number (mA), and the negative signal can be connected to 24V-.

  1. RS485 Digital Signal:

The detector’s RS485 signal is pre-installed on the terminal block. If a 7-inch touchscreen display is selected, the RS485 connection to the touchscreen’s COM2 interface is pre-installed on the terminal block. The host computer can read the concentration data from the touchscreen. See the protocol description for communication protocol details.

  1. Default Condenser Temperature Setting: 4℃.
  2. Regular manual maintenance and cleaning of the dust filter is required to prevent dust from clogging the air passages. Clean, wash, or replace the filter. Filter element specifications: Length 75 * Outer diameter 30 * Inner diameter 20. PE polymer filter element, ceramic filter element, and PTFE filter element are all acceptable.
  3. Regularly check the detector in the pretreatment system and perform zero-point and concentration calibration.

Technical Support

An extractive gas sampling system physically withdraws a sample from the process stream or flue stack and transports it, often through a considerable length of tubing, to an analyzer located in a sheltered, accessible location. This process involves sample conditioning (filtering, cooling/heating, pressure regulation).

In contrast, an in-situ analyzer places the sensor directly into the gas stream. For example, a cross-stack laser analyzer sends a beam of light through the flue gas to make a measurement without ever removing a sample. Extractive systems are more common and versatile, but in-situ systems eliminate sample transport time and sample integrity issues.

The required calibration frequency depends on several factors: the stability of the analyzer, the regulatory requirements (e.g., environmental agencies often mandate daily calibrations for CEMS), and the criticality of the measurement.

For a critical process control loop, a daily or even shift-by-shift verification might be necessary. For less critical monitoring, a weekly or monthly check may suffice. The best practice is to start with the manufacturer’s recommendation and adjust based on the observed drift and performance of the system in your specific application.

The Joule-Thomson effect describes the temperature change of a real gas when it is forced through a valve or other restriction, causing it to expand. In most gas sampling applications, this expansion leads to cooling. This matters immensely because if the gas temperature drops below the dew point of any component in the sample (like water or hydrocarbons), that component will condense into a liquid. This fundamentally changes the composition of the sample delivered to the analyzer, leading to severe measurement errors. To prevent this, pressure regulators are often heated to counteract the cooling effect.

Using standard plant “instrument air” to purge or clean a sample line is generally a bad idea. Instrument air often contains trace amounts of oil, water, and particulates that can contaminate a sensitive gas sampling system. Furthermore, its oxygen content can be hazardous if used to purge lines that normally carry flammable gases. The best practice is to use a high-purity inert gas, such as nitrogen (N₂), for purging. For trace analysis systems, it is essential to use a grade of nitrogen that is purer than the measurement being made.

The most common material is 316 stainless steel (316SS) due to its good general corrosion resistance and strength. For more corrosive applications involving compounds like wet chlorine or acids, specialty alloys such as Hastelloy or Monel are used.

For applications measuring very low concentrations of “sticky” gases like ammonia or H₂S, tubing with an inert internal coating (such as a SilcoNert treatment) is often required to prevent the sample from adsorbing to the tube walls. For some applications, particularly in portable equipment, polymer tubing like PFA or PTFE is also used due to its flexibility and chemical inertness.

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Sino-Inst’s Explosion-proof Gas Sampling System is an online monitoring system for waste gas at plant boundaries/stationary sources, independently developed and manufactured by our company. The sensors are imported high-precision electrochemical, PID photoionization, infrared, and catalytic combustion sensors. It employs a pump-suction sampling method for monitoring. An integrated water and dust removal filter effectively protects the sensors from damage. Customized audible and visual alarm devices are also available.

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