Spark Detection and Suppression Systems

Which facilities require it

Spark detection comes into play wherever combustible solid material is conveyed with air. The typical lines we encounter in the field:

• Wood and furniture industry. Dust collection line for sanding, milling and saw chips; MDF and chipboard production.
• Textiles. Fiber dust aspiration in carding-opening, combing and yarn lines; entry of foreign metal parts into the carding drum is a classic spark source.
• Feed, flour and food. Grain transfer elevators, grinding and milling lines, pneumatic flour transfer.
• Paper and recycling. Scrap transfer lines, waste sorting facilities — the risk of foreign material is highest in the recycling line.
• Metal processing. Grinding and sanding dust aspiration; the risk in aluminum and magnesium dust is at a different level.
• Biomass and pellets. Dryer outlet and transfer after pellet press; material exiting the dryer is already hot.

Where do sparks come from

The spark source is often not a fire. The most frequently occurring causes we see are: metal parts mixed into the material striking a blade or drum, an overloaded or lubrication-starved bearing overheating, material in a blocked line generating heat through friction, product exiting the dryer without sufficient cooling, and electrostatic discharge. None of these produces anything visible to the operator; the particle reaches the filter in closed pipe, in a matter of seconds.

The filter or silo is an ideal environment for this particle: abundant fine, dry and porous material. Fire starts there. Worse still, if there is suspended dust cloud inside the silo, the result is not a fire dust explosion occurs.

How the system works

1. Detection. Infrared sensors are installed on the transfer pipe, viewing into the pipe. Since the pipe interior is dark, the infrared radiation emitted by the passing ember particle is a very distinct signal; the sensor response is in the millisecond range.
2. Evaluation. The signal goes to the control unit. The unit determines which line and at which point the spark was detected.
3. Suppression. The suppression unit downstream of the sensor comes into action; the nozzle sprays the suppressant to cover the pipe cross-section and the particle is extinguished within the line.
4. Isolation if necessary. In case of intense or recurring sparks, a fast-closing damper is activated, material direction is changed or the line is stopped. This stage is configured as an exception state of the system — under normal operation scenario the line does not stop.

Distance calculation: the critical point of the system

The distance between the spark detector and the suppression nozzle cannot be chosen arbitrarily. The particle advances at the air velocity in the pipe; it continues to travel during the system's detection, decision-making and time for the suppressant to reach the nozzle. Therefore:

Minimum distance = pipe air velocity (m/s) × system total response time (s) — a safety margin is added to this.

At typical industrial aspiration velocities, this calculation requires a gap of several meters between the detector and nozzle. In practice we see two errors: placing the nozzle too close to the detector (the particle passes the point before the suppressant sprays) and, because insufficient straight distance exists in the pipe routing, cramming the system immediately after an elbow. In the latter case, turbulence disrupts both detection and spray coverage.

For this reason spark detection must be planned together with the line itself. When added to an existing facility later, a short pipe routing adjustment is usually required.

Suppressant selection

Water use in food and feed lines is evaluated not only in terms of product loss, but also because wet material subsequently creates microbiological and heating risk ; solutions that limit water quantity stand out in these lines.

What it does not solve

Stating the limits of spark detection systems up front prevents false expectations:

• Does not extinguish an existing fire in the silo. Prevents ember particles from entering the silo. Separate protection is required for the silo and filter vessel.
• Does not suppress dust explosion. Explosion suppression and explosion venting are separate disciplines; spark detection reduces ignition sources and thus lowers probability, but does not replace the explosion protection document.
• Does not replace building fire detection. For the production area itself, a separate appropriate detection technology must be selected.
• Does not compensate for cleaning neglect. Dust layer accumulation on surfaces is the fuel for secondary explosion in any ignition; no detection system eliminates this.

Integration with other fire systems

The spark detection unit operates autonomously with its own control unit — this is also correct, because a decision chain routed through the fire panel is not suitable for this speed. On the other hand, the unit must by all means report to the facility's main addressable fire detection system . Typical connections we establish:

• Spark alarm and suppression discharge appear at separate addresses on the panel and are written to the event log.
• The number of recurring alarms is monitored; increasing frequency on the same line signals a mechanical fault (bearing, blockage, foreign material).
• Suppression water pressure drop, cylinder pressure or line fault appears as a fault on the panel — silent disabling is prevented.
• Critical stage (line stop, damper) is connected to the facility's process control system.

What we do as ASPEK

Our work in this field proceeds under three headings:

1. Risk and line analysis. Your dust collection and transfer lines are surveyed; potential spark source points, in-pipe air velocities and suitable installation zones in the pipe routing are identified. The output is a report showing which lines require protection and where it can be installed.
2. Specification and technical evaluation. A brand-independent technical specification is prepared; this way comparable bids can be obtained from multiple manufacturers. You can see our specification approach in our technical specification library .
3. Integration and commissioning support. Relating the system to the facility's fire detection panel, suppression systems and process control; conducting acceptance tests on a scenario basis and including it in the periodic maintenance plan.

To request an evaluation for your facility's dust collection line you can write to us or you can reach us at 0312 385 15 66. For facility-wide detection design, factory and industrial facility solutions page.