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1.  Cable tray, cable tunnel, cable trench, cable interlayer and other cables' fire areas

For fire detection in cable area, LHD can be installed in S-shape or sine wave contact laying (when power cable does not need to be replaced) or horizontal sine wave suspension laying (when power cable needs to be replaced or maintained).

In order to ensure the sensitivity and effectiveness of fire detection, the vertical height between the LHD and the surface of the protected cable should not be greater than 300 mm, and 150 mm to 250 mm is recommended.

In order to ensure the reliability of fire detection, the LHD should be arranged in the center of the protected cable tray or bracket when the width of the cable tray or bracket is more than 600mm, and the LHD of 2-line type should be installed.

The length of linear temperature detection LHD is determined by the following formula:

The length of the detector=the length tray × the multiplying factor

Width of Cable Tray Multiplier
1.2 1.73
0.9 1.47
0.6 1.24
0.5 1.17
0.4 1.12

2.  Power Distribution Equipment

Taking the linear heat detector LHD installed on the motor control panel as an example. Due to the safe and reliable wire winding and binding, the whole device is protected. Other electrical equipment, such as transformer, knife switch, resistance bar of main distribution device, can adopt the same method when the ambient temperature does not exceed the allowable working temperature of linear temperature detector LHD.

For fire detection at protected area, LHD can be installed in S-shape or sine wave contact The detector is fixed with special fixture to avoid mechanical damage caused by stress. The installation mode is shown in the figure 

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3.  Conveyer Belt  

The conveyor belt is driven by the motor belt in the belt roller movement to transport materials. The belt roller should be able to rotate freely on the fixed shaft under normal conditions. However, if the belt roller fails to rotate freely, friction will occur between the belt and the belt roller. If it is not found out in time, the high temperature generated by long-time friction will cause the belt and the transported articles to burn and ignite.

In addition, if the conveyor belt is conveying coal and other materials, because the coal dust has explosion risk, it is also necessary to select the corresponding level of explosion-proof linear heat detector EP-LHD

Conveyor Belt: Design 1

Under the condition that the width of the conveyor belt does not exceed 0.4m, LHD cable with the same length as the conveyor belt is used for protection. The LHD cable shall be directly fixed on the accessory not more than 2.25m above the center of conveyor belt. The accessory can be a suspension line, or with the help of the existing fixtures on site. The function of suspension wire is to provide a support. An eye bolt is used to fix the suspension wire every 75m.

In order to prevent the LHD cable from falling down, a fastener should be used to clamp the LHD cable and the suspension wire every 4m ~ 5m. The material of the suspension wire should be Φ 2 stainless steel wire, and the single length should not be more than 150m (galvanized steel wire can be used to replace it when conditions are not available). The installation method is shown in the figure.

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Convoyer Belt : Design 2

When the width of the conveyor belt exceeds 0.4 m, install LHD cable on both sides close to the conveyor belt. The LHD cable can be connected to the ball bearing through a heat conducting plate to detect overheating due to bearing friction and accumulation of pulverized coal. The general design and installation principle is based on the site conditions without affecting the normal operation and maintenance. If necessary, if the fire risk factor is large, the linear heat detector LHD can be attached on both sides and above the conveyor belt. The installation method is shown in the figure

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4.  Tunnels

The typical application in highway and railway tunnels is to fix the LHD cable directly on the top of the tunnel, and the laying method is the same as that in the plant and warehouse; the LHD cable can also be installed in the cable tray and equipment room in the tunnel, and the laying method refers to the part of the LHD cable laying in the cable tray.

5.   Rail Transit

The safe operation of urban rail transit involves a lot of equipment, especially mechanical and electrical fault and electrical short circuit is an important factor causing fire, especially cable fire is a main cause. In order to find the fire very early in the early stage of the fire and determine the location of the fire, it is necessary to reasonably arrange the fire detector and divide the fire compartment. The linear heat detector LHD is suitable for detecting the cable fire in the rail transit. For the division of the fire compartment, please refer to the relevant specifications.

The linear heat detector LHD is fixed on the top or side of the track and laid along the track. When there is power cable type in the track, in order to protect the power cable, the linear heat detector LHD can be installed by sine wave contact, the same as that applied to the cable tray.

The LHD is fixed on the suspension clamp installed in advance according to the laying line of LHD, and the distance between each suspension clamp is usually 1 m-1.5 M.

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6. Tank Farms for Oil, Gas, and Petrochemical

Petrochemical, oil and gas tanks are mainly fixed roof tank and floating roof tank. LHD can be installed by suspension or direct contact when applied to fixed tank.

The tanks are generally large tanks with complex structure. The figures mainly introduce the installation of LHD for floating roof tanks. The fire frequency of sealing ring of floating roof storage tank is high.

If the seal is not tight, the concentration of oil and gas will be on the high side. Once the surrounding temperature is too high, it is likely to cause fire or even explosion. Therefore, the periphery of the sealing ring of the floating roof tank is the key part of the fire monitoring. The LHD cable is installed around the floating roof seal ring and fixed by the special fixtures.

7.  Application in other places

The linear heat detector LHD can be installed in industrial warehouse, workshop and other places. According to the characteristics of the protected object, the LHD can be installed on the ceiling or wall of the building.

As the warehouse and workshop have flat roof or pitched roof, the installation method of linear heat detector LHD in these two different structure buildings is different, which is explained separately below.

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(1) Installation of linear heat detector LHD in flat roof building

This kind of linear detector is usually fixed on the ceiling with LHD wire at a distance of 0.2m. The linear temperature detector LHD should be laid in the form of parallel suspension, and the cable spacing of LHD cable has been described previously. The distance between cable and ground should be 3M, not more than 9m. When the distance between the cable and the ground is more than 3m, the distance between the cable and the ground shall be reduced according to the situation. If the installation conditions permit, it is suggested that the linear heat detector LHD should be installed close to the flammable area, which has an advantage that the detector can make a rapid response to fire.

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When it is applied in the warehouse shelf, the temperature sensing cable can be installed under the ceiling and arranged along the center line of the shelf aisle, or attached with the sprinkler system pipe. At the same time, the LHD cable can be fixed in the vertical ventilation duct space. When there are dangerous goods in the shelf, the LHD cable should be installed in each shelf, but the normal operation of the shelf should not be affected, so as to avoid damaging the LHD cable by storing and storing goods. In order to detect the low-level fire better, it is necessary to add a layer of temperature sensitive cable in the height direction for the shelf with a height of more than 4.5m. If there is a sprinkler system, it can be unified with the sprinkler layer.

(2) Installation of linear heat detector LHD in pitched roof building

When laying in such environment, the cable laying distance of temperature sensing cable can refer to the cable laying distance of temperature sensing cable in flat roof room.

See the schematic diagram.

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(3) Installation on Oil-Immersed Transformer

Linear heat detector LHD mainly protects transformer body and conservator.

The Linear heat detector LHD cable can be installed on the steel wire rope with a diameter of 6 mm around the transformer body. The number of winding coils is determined according to the height of the transformer, and the winding on the conservator shall not be less than 2 coils; the laying height of the higher coil is about 600 mm below the top cover of the oil tank, and the temperature sensing cable is about 100 mm-150 mm away from the shell, The terminal unit is located on the bracket or firewall, and the Control unit of LHD can be located at the place away from the wall outside the transformer, with a height of 1400mm from the ground.

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