Spark detector RIV-601P/S is an electronic fire alarm device, sensitive to sparks and incandescent bodies in movement.
Its use is particularly recommended on dust collection systems in factories where wood is processed, chipboard or furniture are manufactured, in sawmills and the like, where fires are both probable and frequent.
It is also recommended for the textile industry, especially in cotton mills, in cereal and animal feed mills and storage and in the treatment of hides and leather. And many many others where sparks are produced and they can start a fire.
Spark detector RIV-601P/S contains an element sensitive to the infrared (IR) radiation emitted by incandescent bodies, a series of amplifier and time circuits, and an output relay that provides a
1A 30Vdc changeover contact.
When a spark is detected the relay is operated for 3 seconds (time can be adjusted from 1 to 10 seconds). If the sparks are continuous the relay is operated till 3 seconds after last spark.
The spark detector is designed for installation over the ducts of the dust extraction systems or pneumatic chip conveyors, so that it can see inside the duct through a window. It can also be installed over
screw and belt conveyors or other mechanical systems for conveying chips, sawdust, cereals or animal feed, but sun light or artificial light must not fall directly on the detection window as they might cause false alarms.
The detector is normally installed using the SAM-870 mounting frame, in which it is supported by rubber cushions and is protected from the environment and vibrations.
Dimensioning of Spark Detector System
The elements to be considered for dimensioning the system are the following:
• Ducting: diameter, length and air speed.
• Safety level required: with or without monitoring station.
• Water: pressure.
The duct diameter determines the choice between single detector and pair.
Up to 500 mm diameter, the duct is considered small and a single detector is sufficient (small systems type “A” and “E1”). Over 500 mm diameter the duct is considered large and a pair of detectors is required (large systems type “B” and “E”).
The safety level required determines the choice between systems that perform detection and extinguishing operations (simple systems type “A” and “B”) and those that also provide monitoring (complete systems type “E1” and “E”).
Four systems are then available:
• SYS-A Small simple system. Extinguishing only. Single detector.
• SYS-B Large simple system. Extinguishing only. Double detector.
• SYS-E1 Small complete system. Extinguishing and monitoring. Single detector.
• SYS-E Large complete system. Extinguishing and monitoring. Double detector.
Simple systems type “A” and “B” intercept the spark and automatically extinguish it with a water spray without stopping the production process. For every spark detected the alarm will sound for 3 seconds and the nozzle will spray water for 3 seconds (1-2 liters).
Complete systems type “E1” and “E” intercept the spark, automatically extinguish it with a water spray and check that the spark is extinguished. They perform the alarm and the automatic extinguishing function. For every spark detected the alarm will sound for 3 seconds and the nozzle will spray water for 3 seconds (1-2 liters). They also perform the permanent alarm for missing or not sufficient extinction.
Control panel operates and monitors all the functions of the system, TEST included.
The system must be powered by an external 24Vdc power supply.
The air speed is an important factor for the duct length required. The usual air speed in wood-processing factories is 20-30 meters per second. In textile and other factories air speed is lower, 15 to 20 meters per second.
The duct length must be sufficient to allow positioning of the spray nozzles, and of monitoring detectors if required. If duct length is enough, standard distance of 15 meters, based on 0,2 seconds delay time due to the response delay time of the solenoid valve including water travelling time from the solenoid valve to the nozzles, covers an air speed range from 5 meters per second to 75 meters per second that is highly sufficient for most applications.
The water pressure is very important to a proper functioning of the extinguishing system. At least 1 bar must reach the nozzle for a continuous hollow cone jet. Account must be taken of the pressure drop in the solenoid valve (1/2 to 1 bar), and of pressure drop due to the elevation of the nozzles (1 bar every 10 m of elevation).
In general a pressure of 3-4 bar on the nozzle is recommended. When the water pressure is not sufficient or unstable, it is recommended to mount a small (10-20 liter) pressurized storage tank. Water consumption is moderate. A nozzle sprays about 1-2 liters of water in each 3 sec spray, the flow rate through the nozzles is about 30 liters per minute at 4 bar.
