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series of staggered baffl es that distribute the air and also separate out larger particles, dropping them straight into the hopper. This reduces the load on the fi lters and helps eliminate problems encountered with horizontal mounting. Advances in pleat spacing: Most dust collection cartridges use tightly packed media confi gurations. Though they offer high effi ciency, much of the media surface area is unavailable for fi ltering, allowing dust to remain trapped within the fi lter even after pulse cleaning. A recently introduced pleating technology makes use of hot melt separators that open up the full length of the pleat, allowing the entire depth of the pleat to be utilized. This design thereby allows signifi cantly higher air fl ows per sq. meter of media than what has been achieved in the past.
Because virtually all the media surface is exposed to the air stream, the fi lter holds more dust between cleaning
pulses. The open breathable design also results in signifi cantly lower pressure drop as well as improved dust release characteristics during pulse cleaning, using fewer pulses and therefore less energy.
5. IS THE COLLECTOR OPTIMALLY EQUIPPED FOR SAFETY?
While the most basic function of a dust collector is to keep workers and workplaces safer, not all collectors are created equal from a safety standpoint. As noted above, vertically mounted cartridge systems offer inherent safety advantages over horizontally mounted cartridges. Here are some additional features to consider as you work with your equipment supplier: EU-compliant railed safety platforms and caged ladders can prevent slips and falls when workers access the collector for service. Lock-out/tag-out doors prevent injury caused by inadvertent opening of doors during a pulsing cycle and/or exposure to hazardous dust. Where highly toxic dust is being handled, a bag-in/ bag-out
Horizontally mounted fi lters are subject to uneven dust loading, leading to shorter fi lter life and potential fi re or explosion hazards.
(BIBO) containment system may be required to isolate workers from used fi lters during change-out. Ease of fi lter change-out should be explored. Are the fi lter cartridges positioned for ease of access? Do they slide in and out of the housing readily? Pulling out a dirty overhead fi lter that weighs 45 Kg can result in neck, back and foot injuries, so make sure
the collector you choose is service-friendly. Fire and explosion prevention must also be optimized. A range of features and technologies can be employed, from vertical mounting to the use of fl ame-retardant fi lter media to spark arrestors and sprinkler systems. Where explosive dusts are present, approved explosion vents and/ or other components will be needed for controlled defl agration.
Cartridge dust collector equipped with safety platform.
ceiling and delivering it at ground level. Another advantage of recirculating systems is the reduction in regulatory paperwork. By containing the air indoors, the engineer can deal with work related rules and avoid the time-consuming environmental permitting involved when contaminated air is exhausted outside. Recirculating systems have special safety and performance concerns that must be addressed, but the payback can still be substantial. NOTE: Recirculation may not be allowed for some processes depending on the local rules. In this case, a heat exchanger can be used to recover the energy. Finally, it is not initial cost but total cost of ownership that counts. What will it cost
You might also want to equip your collector with a safety monitoring fi lter, sometimes called a safety fi lter or after-fi lter. This is a secondary bank of high effi ciency air fi lters that prevent collected dust from re-entering the workspace if there should be a leak in the dust collector’s primary fi ltering system.
6. WILL IT PROVIDE THE BEST POSSIBLE RETURN ON INVESTMENT (ROI)?
A safety monitoring fi lter is a recommended component in a recirculating dust collection system that recycles air
downstream of the collector. Where feasible, the best way to maximize ROI is through use of a recirculating system. By recycling heated or cooled air back through the plant, the cost to replace
that conditioned air is eliminated. Many plants report fi ve to six fi gure annual energy savings. Also, dust collectors in shops with high ceilings can often improve the effi ciency of a heating system by taking hot air off the
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to operate, maintain the unit and replace the fi lters? How much compressed air will the collector use? Does the system incorporate “green” features such as variable frequency drives and premium effi ciency fan motors and use high effi ciency fans that can reduce energy costs?
Can it save on maintenance of electrical components such as motors and control panels that are exposed to the dust? A reputable equipment supplier can project these costs mathematically and help analyze the best ways to improve ROI and get the most out of dust collector performance.
Lee Morgan is President of Camfi l Air Pollution Control (APC), Jonesboro, Ark. Camfi l APC is a leading global manufacturer of dust collection equipment and is part of Camfi l, the largest air fi lter
manufacturer in the world.
For further information in Europe, contact Graeme Bell, General Manager, on tel: +44 (0) 1706 363 820, visit:
www.camfilapc.com/europe or email:
europe.apc@camfil.com
Solids and Bulk Handling March 2014 11
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