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Coal Silo Application

Senkox Technologies Inc. has completed various projects in relation to coal storage and transportation. Due to the Intrinsic Safety of the sensor’s construction, the features of real-time temperature monitoring, as well as the flexible alarm settings, the Senkox system is ideal for such sensitive applications.


Coal silos are typically cylindrical shaped storage silos that used to store mined coal. Coal is loaded at the top and unloaded at the bottom, usually onto conveyor belts. This useful fuel source has long been recognized as a fire hazard in storage facilities due to its ability to self-ignite and spontaneously combust. Coal silos store a tremendous quantity of coal, which makes it hard for the heat to dissipate. These accidents usually begin as hot spots generated by oxidation and the poor release of heat deep in the structure. Eventually, this can result in widespread fire. Therefore, it is imperative to monitor any temperature rise and detect a hot spot in its early stage before culminates in combustion.

Coal silos at a coal mine.

A fire outbreak in a coal silo is both dangerous and costly. In the event of combustion, several tons of smoking coal will need to be drained from the silo onto the feeder deck floor. This leads to a huge mess, an expensive clean up, and a pause in production. Additionally, the damaged equipment will need to be replaced.

Coal silo discharge pipe glowing red hot due to an undetected hot spot.

Linear heat detection is an ideal solution to continuously measure the temperature inside the silos. The detection sensors must be very durable in order to withstand the stress of coal loading and unloading. However, the conventional linear heat detection technology may not be an adequate fire safety solution as the immense pressure inside the silo can easily damage a conventional linear heat sensor. The continuous loading and unloading of coal can also decrease the life a sensor.

Due to the large volume of the silo, the temperature monitoring system must be composed of distributed sensors designed to cover large areas.  Senkox HSD™ Linear Heat Sensors (LHS) with flange support can be installed vertically in the middle of the coal silo. Additionally, the LHS sensors are able to withstand high temperature, abrasion, and pressure, making it an excellent fire detection solution for coal silos.



In order to monitor the client’s coal silos, a linear heat monitoring system was needed. The Senkox HSD™ Linear Heat Sensor solution is monitoring the real-time temperature of the stored coal.

Senkox designed a special sensor for coal silos that lasts for many years undeterred by the environment’s intense abrasion. This special sensor is structured using braided stainless steel strands that protect the internal structure of sensor from external pressure and stress. This design also protects sensor from any damage caused by the loading and unloading of coal.

The Senkox HSD-T-CS braided stainless steel sensor cable.

This design comes from Senkox’s years of field experience, which led the company to engineer several versions of the cable. Traditionally, fire protection cables for coal silos link together point-type linear heat sensors inside a rugged stainless steel tube that is welded to the top of the silo. When coal is loaded into the silo, it bombards the protective steel tube, bending it over a mere few months. In turn, the conventional linear heat sensor becomes deformed over time. Senkox recognized the issues with the conventional design and worked year after year to create a cable that was both rugged yet flexible: the cable veers around the coal poured over top.

Another design consideration was how to mount the cable vertically from the top of the silo with minimal stress to the cable itself. Thanks to a special stress release mechanism, the cable can handle up to 2000 kilograms of weight. Senkox’s coal silo fire protection design provides peace of mind for years through the cable’s flexibility, durability, and stress release mechanism.

The mounting kit suspends the cables from the top of the silo.


For this case study, Senkox HSD™ Linear Heat Detection System was installed on four silos, each of which was 12 meters high and 15 meters wide. The data acquisition (DAQ) modules were placed 30 meters away from the silos. Each silo was monitored by one DAQ module connected to four sensors cables.

Senkox HSD Linear Hot Spot Heat Detector Coal Storage

Installation diagram of the four silos.

A total of 16 Senkox linear heat detectors were installed by draping them from the top of the silos to monitor the content inside. This is especially useful for detecting possible hotspots forming near the bottom of the silo, where heat that has failed to dissipate may lead to a problem.

The special stress release mounting kits were used to secure the sensor on the top of silos. The mounting kit sustains all of the stress so that the sensor may operate freely. Senkox also customized each mounting kit to fit the specific needs of this client’s silos.

The four coal silos onsite.

Should any unusual temperature increase occur, the user will be alerted because Senkox cable monitors the real-time temperature and rate-of-temperature-change.

Dome application: Coal domes are used for larger size coal storage. The airtight structure of a dome helps keep moisture out. A large mechanical “arm” moves the coal around inside the dome in order to keep the coal moving and release undissipated heat. Coal that is missed by the arm, as well as residual coal dust, can build up along the interior walls of the dome. This is the greatest concern for spontaneous combustion. The Senkox HSD™ LHS sensors can be installed vertically or horizontally along the outside walls as these areas most likely to experience hot spots from coal buildup. Real-time data regarding temperature fluctuations can then be monitored by the client. Select Senkox sensors can even provide data on the size and position of the hotspot.

Senkox HSD Linear Hot Spot Heat Detector Coal Storage Senkox Linear Hot Spot Heat Detector For Coal Storage


Fire protection is of highest importance in coal storage due to coal’s ability to spontaneously combust. The Senkox HSD™ Linear Heat Sensor allows the client to monitor the four coal silos for any hotspots in real time, and ensures that any rise in temperature will be addressed before smoldering coal is transported along a conveyer belt. Implementing extensive field experience, Senkox designed a braided stainless-steel cable and a stress release mechanism that survives years in the abrasive environment, unlike other linear heat solutions for coal storage. The Senkox solution works to protect the storage unit from the unique self-igniting properties of coal, but more importantly, to keep the people working at the coal mine safe from fire.