**1. Installation of Combustible Gas Detection System**
The installation of a combustible gas detection system typically includes a gas detector and an alarm control panel. These systems are widely used in the petroleum, gas, chemical, and oil tank industries, where toxic or flammable gases may be present. They play a critical role in detecting leaks in both indoor and outdoor areas, ensuring safe production and protecting personnel from potential hazards.
When a toxic gas is detected, the sensor converts the gas signal into an electrical signal—either voltage or current—and sends it to the alarm controller. The device then displays the percentage of the lower explosive limit (LEL) of the gas. If the concentration exceeds the pre-set alarm threshold, an audible and visual alarm is triggered. This allows on-site personnel to take immediate action, preventing potential explosions or other dangerous incidents.
When installing such systems, it's important to consider several key factors:
(1) Identify all possible leakage points of the monitored equipment. Analyze the pressure, direction, and other relevant factors to create a distribution map of the sensors. Classify these points into three levels (I, II, III) based on the severity of the potential leak.
(2) Determine the direction of gas flow during large-scale leaks, taking into account factors like air movement and location-specific conditions.
(3) Based on the gas density (whether it is heavier or lighter than air), combine this with airflow patterns to create a 3D leakage flow diagram. Set the initial alarm points at the downstream location of the gas flow.
(4) Assess whether the leak is a micro-leak or a jet-like release. For micro-leaks, place the sensor close to the source. For jet leaks, position it slightly away from the leak. Combine these factors to finalize the layout plan, which helps estimate the number and type of detectors needed.
(5) In areas where large gas leaks are likely, install a detection point every 10–20 meters as per regulations. For unattended, small, or non-continuous pumping stations, ensure that a detector is placed near the intake area.
(6) For hydrogen leaks, install the detector above the leak point, as hydrogen is lighter than air.
(7) For gases denser than air, place the detector below the leak point, and pay attention to surrounding conditions. In areas where toxic gases tend to accumulate, special attention must be given to setting up safety monitoring points.
(8) In open environments where gas can spread freely, poor ventilation may lead to localized concentrations of toxic gas reaching or exceeding the lower explosion limit. These areas require careful monitoring. According to field accident analysis, more than half of the incidents were due to incorrect installation or calibration. Therefore, following proper installation and calibration procedures is essential to reduce failures and ensure reliable operation.
**2. Installation Precautions for Gas Alarms**
(1) The alarm probe contains a detection element that interacts with the gas sensor. It consists of a platinum wire coil coated with alumina and a binder, forming a spherical structure. The outer surface is coated with rare metals like platinum or palladium. During installation, care must be taken to avoid damaging the probe.
(2) The alarm should generally be installed at a height of 160–170 cm to allow maintenance personnel easy access for routine checks.
(3) As a safety instrument, the alarm should be placed in a location where staff can easily see and hear the sound and light alerts, ensuring timely response to potential hazards.
(4) Avoid placing the alarm near strong electromagnetic fields, such as high-power motors or transformers, as they may interfere with the device’s operation.
(5) The installation height of the indoor probe depends on the gas density. If the gas is lighter than air, install the probe 30 cm below the ceiling and pointing downward. If the gas is heavier, install it 30 cm above the floor and pointing upward.
The controller is connected to the detector using a three-core shielded cable (with a minimum core diameter of 0.75 mm, as per national standards). The shield layer should be grounded to the controller chassis. When using RVV cables, they should be run through metal conduits, which must also be reliably grounded.
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