**1. Installation of Gas Detection Systems**
The gas detection system typically includes a combustible gas detector and an alarm control panel. It is widely used in industries such as petroleum, gas, chemicals, and oil storage facilities where toxic gases may be present. These systems are essential for detecting leaks in both indoor and outdoor hazardous areas, playing a critical role in ensuring the safety of personnel and production processes. When toxic gas is detected, the sensor converts the gas signal into either a voltage or current signal and sends it to the alarm unit. The instrument then displays the percentage of the gas concentration relative to the lower explosive limit (LEL). If the gas concentration exceeds the set alarm threshold, an audible and visual alarm is triggered, allowing on-site personnel to take immediate safety measures and prevent potential explosions.
When installing fixed gas detectors, it is important to consider several key factors. Once installed, the location should not be easily changed. Therefore, the following points must be carefully considered during the planning phase:
(1) Identify all potential leakage points of the monitored equipment. Analyze factors such as pressure, direction, and other environmental conditions. Create a distribution map of the probes and classify them into three categories based on the severity of the leak: I, II, and III.
(2) Determine the direction in which the toxic gas will spread in case of a large leak, taking into account factors like airflow direction and the location's layout.
(3) Based on the gas density (whether it is heavier or lighter than air), combine this with the airflow pattern to create a 3D flow diagram. Use this to establish an initial set-point scheme at the downstream position of the gas flow.
(4) Study the type of leakage—whether it is a microleakage or a jet-like leak. For microleakages, place the probe close to the source. For jet-like leaks, position it slightly away from the source. Combine these conditions to finalize the installation plan, which helps estimate the number and type of detectors required.
(5) In areas prone to large gas leaks, install a detection point every 10–20 meters according to regulations. For unattended, small, or non-continuous pumping stations, ensure that detectors are placed at the intake area to monitor possible leaks.
(6) For hydrogen leaks, install the detector above the leak point, as hydrogen is lighter than air.
(7) For gases denser than air, install the detector below the leak point, and pay attention to surrounding conditions. In places where toxic gases can accumulate, special attention should be given to setting up monitoring points.
(8) In open areas where toxic gas may diffuse or escape, poor ventilation can lead to dangerous concentrations near the lower explosion limit. These locations require careful monitoring. According to field accident analyses, over half of incidents were caused by improper installation and calibration. Therefore, proper installation and calibration procedures are crucial to reduce failures and enhance system reliability.
**2. Installation Precautions for Gas Alarms**
(1) The alarm probe contains a combustion gas sensor, typically made of a platinum wire coil coated with alumina and a binder, forming a spherical structure. The outer surface is often covered with rare metals like platinum and palladium. During installation, handle the probe with care to avoid damage.
(2) The alarm should generally be installed at a height of 160–170 cm, making it accessible for routine maintenance by technicians.
(3) As a safety device, the alarm should be placed in a location where staff can easily see and hear the alerts, ensuring quick response and hazard mitigation.
(4) Avoid placing the alarm near strong electromagnetic fields, such as high-power motors or transformers, as they may interfere with its operation.
(5) The installation height of the indoor probe depends on the gas density. If the gas is less dense than air, install the probe 30 cm below the ceiling and pointing downward. If the gas is denser, install it 30 cm above the floor and pointing upward. Connect the controller to the detector using a three-core shielded cable (with a minimum core diameter of 0.75 mm as per national standards), and ensure the shield layer is grounded to the controller chassis. When using RVV cables, run them through metal conduits and ensure the conduits are properly grounded.
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