Tunnel gas monitoring

With the development of science and technology becoming stronger and stronger, the development and construction of highways are increasing day by day, in which the proportion of tunnels in the construction is also increasing. Tunnel excavation work is also highly valued by project construction companies and the state. Tunnel is a limited space, ventilation is not good, in the excavation construction is very easy to produce combustible gas and toxic and harmful gases, these gases are trapped in the tunnel, the tunnel construction personnel’s health and safety of life threatening, but also may be a major disaster and loss of the tunnel project, so Tunnel gas monitoring prevention and control is a key point of the tunnel construction, the tunnel of hazardous gas Therefore, Tunnel gas monitoring is the key point of tunnel construction, and 24-hour on-line detection of harmful gases in tunnels is also an indispensable protective measure for tunnel construction.

Tunnel gas monitoring
Tunnel gas monitoring

Solution

In the tunnel excavation process, the most likely to produce toxic and harmful gases are: CO carbon monoxide, CH4 methane, H2S hydrogen sulfide, O2 oxygen, SO2 sulfur dioxide, CO2 carbon dioxide, in addition to preventing the operator from lack of oxygen asphyxiation, the concentration of O2 oxygen must also be detected.

Monitoring location: Tunnel entrance, the middle of the tunnel, tunnel bifurcation, tunnel excavation and blasting place near the tunnel and other dangerous places that are prone to gas leakage.

Monitoring gases and other hazardous substances: CO, CH4, H2S, O2 , SO2 , CO2, dust particles (PM2.5+PM10)

Installation Requirements: The installation standard of each country is different, taking China as the standard is 25 square meters to install an Industrial Gas Detector, the user can also be based on the actual situation of the site to determine.

Installation Height: The detector should be installed at a height of more than 30 centimeters from the ground to prevent water from splashing in. In general, to detect harmful gases with specific gravity less than air, the probe should be installed above the house or equipment; for harmful gases with specific gravity greater than air, the probe should be installed close to the ground. The detector should be mounted with the probe pointing downward.

FS10201 (1)
Industrial Gas Detector FS10201

Data transmission

According to the actual situation of the site to determine how many gas detection alarms installed in each monitoring area, all gas detectors must have real-time data display and sound and light alarm function. The relevant gas concentration value detected by the detector at each point can be transmitted and communicated to the gas alarm controller in the janitor’s room or the control room in the following two ways. When any of the monitored gas concentration reaches the alarm value, the nearby fan will be automatically activated through the relay to carry out the air circulation process. At the same time, the corresponding channel of the gas alarm controller in the communication room will also alarm.

1.Wired transmission

There are two ways of wired transmission: 4-20mA and RS485.

4-20mA is called analog signal output, also called linear output, wiring for the wiring system.

RS485 is called digital signal output, using the standard modbus protocol, wiring for the bus system.

2.Wireless transmission

There are two common ways of wireless transmission: LORA and 4G transmission.

Lora wireless module in the industrial field has been widely used, its main advantage is that, in the same power conditions, it is much farther than other series of wireless modules, in the open environment under the shelter of the transmission distance is 5 kilometers, if there are obstacles in the middle of the transmission distance will be attenuated, depending on the site, in addition, Lora belongs to the low-power, with good anti-jamming ability, high sensitivity.

4G wireless transmission is a direct mode of data interaction with the server, through the 4G signal to the gas concentration data sent to the cloud platform, and ultimately transmitted to the user’s computer or cell phone to view, you can also set up a cell phone call or text message alarm prompts, note that the use of the 4G module under the premise of the tunnel must be guaranteed that the network is smooth and stable, the advantage of the absence of distance limitations, as long as there is a signal can be transmitted anywhere.