Gas Detector: Installation and Precautions
As we all know, a gas detector is an instrument used to detect changes in the concentration of harmful gases at work sites. In some limited spaces with large areas and complex environments, the working environment can be said to be changing rapidly. Gas detectors can remind staff to take preventive measures in a timely manner, and can also let companions know each other's location and distance. Today we will introduce the installation, maintenance and precautions of the gas detector.
The first step is to install gas detectors in areas where there may be gas leaks. The installation of the gas detector must be firm, and the installation position is determined according to the specific gravity of the gas to be measured relative to the air.
In order to use the detector correctly and prevent its malfunction, please do not install it in the following locations:
- Places directly affected by steam and oil fume.
- Air supply ports, ventilation fans, doors and other places with large air flow.
- Places with many water vapor and water droplets (relative humidity: greater than 90%).
- Places where the temperature is below -40°C or above 70°C.
The second step is wiring. The wiring should be highly shielded to prevent electrical signals from being interfered with, put the wires in place, and open the top cover.
- The gas detector generally adopts a two-wire transmission system. Connect the terminals marked L+ and L- to the T+ and T- terminals of the controller. The lines are not polarized. After connecting the lines, fasten the case.
- After the wiring is completed, supply power to the detector. After preheating, it will automatically switch to monitoring state.
Storage without electricity: The detector is first placed in an environment with a temperature of -25°C ± 2°C for 24 hours, and then recovered for at least 24 hours under normal environmental conditions. After this, the detector should be placed at a temperature of 55°C ± 2°C for 24 hours, and then recovered for at least 24 hours under normal ambient conditions. After the test, the detector should not have damaged coating and corrosion, the function should be normal, and the difference between the alarm action value and the alarm setting value should not exceed ±3% LEL.
Position (except for inhalation detectors): Measure the alarm action value of the detector at every 45° rotation on the three mutually perpendicular axes of X, Y and Z respectively. The difference between the alarm action value of the detector and the alarm setting value should not exceed ± 5% LEL.
High concentration flooding performance (applicable to explosion-proof detectors only): During submersion, the detector should send out an alarm signal or a fault signal or a clear indication signal that the gas concentration exceeds the measurement range. After submersion, the detector shall meet one requirement of the following:
- The detector cannot be in normal monitoring state.
- If the detector can be in a normal monitoring state (which can be operated manually), the difference between the detector's alarm action value and the alarm set value should not exceed ±5% LEL.
Alarm repeatability: Under normal environmental conditions, the alarm action value of the same detector is measured 6 times, and the difference between the alarm action value of the detector and the alarm setting value should not exceed ±3% LEL.
High-speed airflow: Under the condition that the airflow velocity is 6m/s, the difference between the alarm action value of the detector and the alarm setting value should not exceed ±5% LEL.
Voltage fluctuation: The power supply voltage of the detector is ±15% of the rated power supply voltage, and the difference between the alarm action value and the alarm setting value should not exceed ±3% LEL.
Long term stability performance: The detector should be able to operate continuously for 28d under normal environmental conditions. During the test, the detector shall not send out an alarm signal or a fault signal. After the test, the difference between the alarm action value of the detector and the alarm set value should not exceed ±5% LEL.
Insulation withstand voltage performance: The insulation resistance between the external live terminals, power plugs and the outer casing of the detector with insulation requirements should not be less than 100MΩ under normal environmental conditions, and should not be less than 1MΩ under humid and hot environments. The above parts should also use an AC voltage test detector with a rated voltage withstand frequency of 50Hz, an RMS voltage of 1500V (when the rated voltage exceeds 50V) or an RMS voltage of 500V (when the rated voltage does not exceed 50V) for 1min. During the test, the detector should not have discharge or breakdown phenomenon, and the function of the detector should be normal after the test.