DUST COLLECTION SYSTEMS
Sandblasting and shot blasting equipment will not operate at their full potential if they are not equipped with a proper dust collection system able to capture dust generated from their usage. This is why, for 40 years, IST has provided dust control systems specially designed to enhance the efficiency and performance of sandblasting and blast cleaning equipment.
The dust collector plays different roles in such a system. First and foremost, it increases the visibility of the operator by evacuating the dust cloud generated from the media impact on the workpiece out of the work environment. Additionally, it contributes to the smooth running and maintenance of the blasting equipment by preventing dust and fine particles from damaging critical mechanical parts. Finally, it contributes to the workers’ health and to maintaining a clean work environment by returning clean, filtered air into the work space.
Our wide range of dust collectors integrates the latest monitoring, automation, and control technologies. This way, you may focus on your core business with the assurance of working in a clean and safe work environment.
Whether you are looking to provide your sandblast cabinet, abrasive blast room, or automated finishing systems with a proper dust collection system, IST has the solution you need and which fits within your budget.
Simply put, there are three main dust collection systems for sandblasting and shot blasting equipment.
|Dust Bag||Bag-House Dust Collector||Cartridge-Type Dust Collector|
ISTblast DB13 Dust Bag has a filtration capacity of 13 square feet and may be installed directly on the exhaust system of a sandblasting cabinet. As the sandblast system is switched on, the bag inflates and releases dust build-up from its sides. Dust may then be collected in the dust pail supplied with the system.
Bag-house dust collectors are more effective than the DB13 dust bag. First, the dust cloud is carried far away from the cabinet, but also, the filtration capacity ranges from 50 to 330 square feet. As for the rest, the principle of functioning is very similar. When the system starts, filtering bags (also called sleeves due to their rounded and narrow shape) inflate to allow a small quantity of dust to stick to their sides in order to fill in their pores and give them their optimal filtration capacity. After each use, the filtering bags must be manually or mechanically shaken in order to release excess amounts of dust. Air contaminated with dust is sucked through the filtering bags by means of an impeller powered by an electrical motor.
Impeller on the clean vs dirty side (of dust and abrasive media)
The impeller can be mounted onto the cabinet (on the dirty side) to push contaminated air towards the dust collector or, oppositely, on the dust collector (on the clean side) in order to suck air from the cabinet. The second configuration considerably increases the performance of the dust collector while extending the life span of the impeller.
Indeed, when the impeller is mounted on the cabinet, it pushes the dust and abrasive media through the impeller’s turbine, which causes premature wear and limits its ability to convey dust due to restriction. On the other hand, when the impeller is mounted on the clean side dust collector, the turbine doesn’t come across friction with neither dust nor abrasive media. The sucking power of the impeller is also enhanced due to the absence of restriction.
|Dirty side||Clean side|
Operation and maintenance of a bag-house dust collector
Bag-house dust collectors are relatively easy to operate and maintain. Before and/or after each use, filtering bags must be shaken in order to dislodge dust build-up from their sides, and the dust collection container – normally located at the bottom of the dust collector’s hopper and actionable from a drain valve – must be emptied. Some models are equipped with a sieve drawer which traps larger debris. Filtering bags are easily replaceable when they stop performing as they should – when the system is unable to evacuate the dust cloud produced by the impact of the media onto the workpiece, or when the system is no longer able to let air circulate normally. We recommend using these dust collection systems for regular industrial users of sandblast cabinets.
Available bag-house dust collector models
This type of dust collector is available in different filtration capacities:
Cartridge-type dust collectors are far more efficient than bag-house dust collectors due to their nano fibre filtering cartridges. These dust collectors are equipped with an impeller located on the clean side, powered by an electric motor that can achieve between 2,000 and 50,000 CFM. Each unit can be fitted with 6 to 224 filtering cartridges and can yield a filtration capacity of up to 100,000 cubic feet per minute (pi3/min.). The modular conception of this line allows the bundling of multiple units together in a closed loop system in order to multiply the filtration efficiency of the system and accommodate the most demanding sandblasting applications.
Unlike conventional horizontal-design dust collectors where cartridges are mounted horizontally and lose up to 30% of their filtration capacity, the vertical design of ISTblast dust collectors allow the dust to fall freely straight down to the bottom of the unit in order to maintain 100% efficiency at all times.
These dust collectors can be installed inside (under some conditions and in accordance with the fire codes in force in your jurisdiction) or outside the building. They are fairly easy to maintain and only require you to regularly empty the dust barrel and replace the clogged cartridges when they reach the end of their service life and are no longer able to filter dust. They can also be equipped with a variety of safety designs and features to prevent fire or explosion when the application generates combustible dust.
The use of cartridge-type dust collectors is advised on blast booths and automated finishing system to optimize the performance while reducing the wear and tear on system’s critical components.
The filtering bags are made of circular knit polyester fabrics, providing them with excellent filtration efficiency. During the first few minutes of operation, the filtering bag must fill in its pores in order to perform correctly. Thus, it is normal to see dust escaping from the bags until the filtering media becomes tightly hermetic. Once the bag is completely sealed, this porous fabric can capture up to 99% of particles down to 5 microns or over.
Their unique, seamless tube design consists of a patented “loop pile” surface that easily removes dust build-ups during the cleaning cycle, while preventing the blinding or plugging of the fabric. Eliminating the seam also offers an additional filter area, providing increased airflow.
Unlike conventional woven and needled textiles, the thickness and fibre density of the circular knit fabric provide a high permeability, reducing pressure drop conditions, with excellent filtration efficiencies. Additionally, electrically conductive carbon fibre is knitted into the fabric to protect against static build-up by constantly drawing off static charges to the ground. Uncontrolled electrostatic build-up could lead to an explosion or fire when combined with sufficient concentration of combustible dust floating in the air. The anti-static yarn also plays a role in increasing filtration efficiency by avoiding static cling, due to opposing static charges between the dust and the filter bag which prevent the bag from releasing the “dust cake”.
Filtering Bag Cleaning System
To control dust build-ups on the sidewalls of the filtering bags to an acceptable level in order to allow air pass through the media, bags must be manually or mechanically shaken in order to release excess amounts of dust, which then falls down into a container. IST offers three means to shake filtering bags:
The filtering cartridges are made of the industry’s smallest nanofiber (10 microns). Best in class MERV 15 efficiency on sub-micron particulate. This incredible technology is able to capture 100% of foreign particulates down to 0.3 µM in size and obtain unequaled surface loading capabilities with nano-sized interfibre pores. The fibres of a conventional cartridge media are six times larger, which allows small particles to become deeply embedded within the media substrate.
The vertical design of ISTblast cartridge-type dust collectors maximizes the filtration efficiency of these cartridges, while minimizing the maintenance required on horizontal design cartridges. Indeed, cartridges mounted horizontally lose up to 30% of their filtration capabilities due to dust accretion at the bottom cavity of the media, and for this reason, horizontally-mounted cartridges must be rotated periodically in order to maximize their performance and durability. This is not the case for vertically-mounted cartridges, since they allow dust to fall freely down to the bottom of the dust collector without altering their filtering efficiency.
Filtering Cartridges Cleaning System
The cartridges are cleaned by a pulse of compressed air blowing inside them. The reverse pulse momentarily halts the flow of air passing through the cartridges in order to remove dust on the outer surface. The dust then falls to the bottom of the barrel.
The pulse intervals are controlled by the DCT1000 Sequential Controller, which collects and compares static pressure data on both the dirty and clean side of filters simultaneously. When the pressure loss falls out of the predefined limit, the system generates pulses inside the cartridges until the pressure loss is within the acceptable interval.
When the sequential controller is no longer able to stabilize the static pressure, it is time to replace the filter cartridges. Unlike conventional cartridges found on the market, it is unnecessary to clean them since the dust builds up on its surface only rather than deeply inside the substrate, so it releases easily upon the pulse. Also, replacing the cartridges is fairly easy – it can be accomplished from outside the dust collector’s housing and without tools.
If your application produces combustible dust, it is extremely important to choose a dust collector design and installation that protects your workers against the risk of fire or explosion. This is why IST provides a variety of designs, as well as active and passive safety features that can contribute to protecting your operators and making your dust collector installation fully compliant with security standards published by the National Fire Protection Association (NFPA).
Available options include abort dampers, blow back dampers, explosion vents, rotary air locks, as well as fire detection and suppression devices. When necessary, a compliance certificate can be issued by an external audit body in order to assess that your equipment complies with requirements in force and that it does not present a risk to workers.
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