Spark extinguishing for filters

Producer: T&B electronic

Spark extinguishing systems prevent sparks from entering aspiration systems, which can lead to fires and explosions that endanger equipment and employee lives.

When a spark is detected inside the equipment, the system’s sensors automatically actuate, sending a signal to the control unit to activate the fire extinguishing system. The extinguishing agent is fed into the exhaust duct through special nozzles. Passing through the created barrier, the extinguishing agent extinguishes the sparks, eliminating possible dangerous consequences.

Description
Technical information
Information files
Installation and maintenance

Description

Workplaces where dust or pollutants are emitted are usually equipped with extraction and filtration systems. However, the possibility of glowing particles entering the filter can cause the filter elements to catch fire. To protect these filters, T&B fire suppression systems are used to ensure the safety of buildings. The underlying principle of effective fire protection is a comprehensive concept adapted to the specific operating conditions. Fire detection in the filter is carried out using highly sensitive infrared and thermal sensors, ensuring maximum reliability and preventing false alarms.

Argon, an inert gas, is preferably used to extinguish fires and provides maximum safe extinguishing efficiency for personnel. After extinguishing is complete, argon can be safely removed through the ventilation system. CO2 gas, often used for extinguishing, may only be recommended where the protected object is outside buildings and where there is no risk to personnel. Reducing the pressure in the protected object to a safe level is achieved through on-site pressure relief zones. The centrepiece of the T&B fire extinguishing system for building protection is the BM 4-2G fire extinguishing control unit. It not only evaluates the sensor signals, but also takes the necessary measures to control the equipment (including switching off the fans and closing the valves on the raw and clean gas pipework and, if necessary, on the filter outlet) and to start extinguishing. The extinguishing gas quickly enters the fire, replacing oxygen and thereby suppressing the fire.

Advantages

Fast explosion suppression – minimal time elapses from detection to explosion suppressant delivery.
The products of the explosion do not spread outside the equipment.
The inert argon gas ensures maximum extinguishing efficiency and safety for personnel.
The system is designed in accordance with VdS directives 2380 and 3445 and DIN EN ISO 19353:2016.
The T&B fire suppression system for building protection complies with the requirements of BGR 134 issued by the Employers’ Liability Insurance Association.

Technical information

In pneumatic conveyor lines, spark detectors and spark suppression systems must be installed downstream of the fan as it can be a source of sparks. Spark detectors detect a minimum number of infrared rays and transmit a signal to the spark alarm unit. The fire extinguishing system is triggered within milliseconds by injecting extinguishing water through special nozzles into the exhaust pipe. Flying sparks must pass through the extinguishing mist and be safely extinguished.

The minimum distance between the spark detector and the extinguishing media depends on the air velocity in the exhaust line and the reaction time of the extinguishing system. This distance is calculated as the product of the air velocity in m/s by a safety factor of up to 0.3 s (depending on the diameter of the supply line). The safety factor determines the time between the detection of a spark and the activation of the extinguisher. During this time, an effective extinguishing water mist must form that can reliably extinguish sparks. Consequently, the higher the air velocity, the greater the distance between the sensor and the extinguishing system must be to start the extinguishing process before the spark reaches the extinguishing point.

All pipework to the filter and chip hopper must be fitted with a spark detection system downstream of the fan. This system shall include at least two spark detectors monitoring the pipeline cross-section. The spark extinguishing system shall consist of a quick-opening solenoid valve and at least one nozzle. The extinguishing nozzles have a cap to prevent contamination. The extinguishing process continues until the last spark is detected, after which the automatic extinguishing system is automatically switched off. The spark extinguishing system is always in standby mode to react immediately to new sparks. The minimum extinguishing time is five seconds and is automatically extended if sparks continue to arrive. Individual sparks are effectively extinguished during production.

The machine can be switched off by means of an adjustable spark threshold, which can be set to between 1 and 999 sparks in a certain period of time. The number of sparks detected and the trigger threshold are displayed on the spark alarm unit. For optimum atomisation distribution in an automatic fire extinguishing system, a flow pressure of at least 5 bar is required. If this is not the case, a pressure booster consisting of a vertical centrifugal pump with a diaphragm pressure tank and a storage tank is used. It is possible to connect the extinguishing water to an existing sprinkler system. Fire extinguishing systems located in areas subject to frost shall be equipped with electric heating. The heating shall be controlled by an external thermostat with appropriate heating tape control. All extinguishing water pipes and the extinguishing system itself must be insulated.

The area around valves and extinguishing nozzles must be capable of being stripped for maintenance. Spark detectors have inbuilt testing facilities. The new generation of spark detectors has an automatic detector testing system, eliminating the need for manual testing. The extinguishing water monitoring system continuously monitors extinguishing processes and visually displays them on the spark alarm unit.

If the filter system is operated with a return air system, by-pass smoke sensors are installed in the ducts, which react instantly to a smouldering fire in the filter hoses and switch off the fans. Two differential temperature sensors are also installed in the filter system and react when temperatures exceed 90°C. They can either alarm or switch on the fire extinguishing system. The spark alarm units are equipped with a microprocessor-based monitoring system that stores and displays fire alarm events and faults in text form. Up to 2500 events can be stored.

Information files

Product Description

Installation

The spark arrestor system may only be installed by an installation company approved by VdS.

The use of approved components and devices is mandatory. For each spark extinguishing system installed, the approved installer must submit an installation test, a schematic drawing detailing the functions and implementation points, and a hydraulic calculation. These documents must be provided to VdS during the acceptance procedure. Spark arresting systems must be regularly inspected and maintained by an authorised installation company. Any faults identified must be rectified immediately. The normal maintenance intervals are six months.

The company responsible for operating the spark extinguishing system must keep a logbook in which faults, technical checks and other events are recorded.

Advantages of working with ATEX.CENTER

The customer will have no problems with the supply of components and service. ATEX.CENTER is an official distributor of the leading European distributor of explosion protection equipment RSBP spol. s r.o. Our specialists periodically confirm their qualification in his commission of expertise.

The customer will not have any problems with the supply of components and service maintenance. ATEX.CENTER.

We open representative offices where our customers work. The customer saves time on service maintenance.

We cooperate with European experts in the field of ATEX. The customer receives professional experience in explosion protection.

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