There are a number of factors to consider when adding a blast room or abrasive blasting system to your powder coating or painting operation. No matter what type of dry blasting system you are considering, this guide is designed to help answer your questions and plan for your success.
Note: Although uncommon, wet blasting systems, also known as slurry blasting systems, are sometimes used. This article focuses on dry blasting systems, particularly those designed for manual blasting by one or more operators inside a walk-in size steel enclosure.
Part 1: The Blasting Enclosure
Before deciding on a blast room, it’s best to familiarize yourself with some of the features common across most manufacturers. Almost all blast rooms feature a square roof design instead of hip-style roofs. The square roof construction allows for more operator movement, easier load-in and load-out, and has better lighting. Light gauge hip roof models – which are often the cheapest on the market – may not provide the durability and usability you are looking for.
Wall and roof panels are usually available in thicknesses that range from 18 to 10 gauge or thicker. As a general rule, the heavier the wall thickness, the higher the cost. Everyone wants a heavy duty blast room, but heavier construction often offers no real benefit because high-wear areas are typically covered by rubberized shielding.
Blast rooms are commonly equipped with a moderate number of multi-tube fluorescent light fixtures and feature safety glass in order to meet code.
Upgrades To The Blasting Enclosure
While there isn’t much to upgrade when it comes to the cabin of conventional blast rooms, the door design is one area of the cabin’s construction where upgrades are typically worth the cost. The majority of professional-grade blast rooms include conventional swinging doors with louvered openings. Premium models may feature perforated doors with adjustable splash shields to keep spent media inside the blast room while allowing fresh air to be drawn into the enclosure. Ruggedized fabric or rubber roll up doors can be requested at an additional cost. They help reduce the amount of shop space required.
A typical blast room ships with one full-width, full-height door set, and may have one or more separate personnel doors. Some manufacturers offer a curtain wall or curtain door option to reduce cost, but these configurations are not popular with most shop owners because they don’t provide as much containment as other designs.
Get The Right Size
Make sure the blast room is the right size. Many of the considerations we outlined in our powder coating oven size guide will be applicable here, but make sure you give your parts and your operator plenty of room. For example, if the parts you need to blast are very tall, consider adding some additional height to the cabin so you won’t constantly be blasting into your light fixtures or the unprotected ceiling surface. Also, if the part you want to blast takes up the majority of the cabin, give your operator extra width and length to safely work around the part without standing in a stream of blasting media bouncing back towards him.
Part 2: Blast Pot
The blast pot (also referred to as a blasting pot, pressure pot, pressure vessel, media blaster or portable blaster) is the appliance that does the actual blasting. There are a number of blast pots on the market, but all of them work essentially the same way. A blast pot is a pressurized container with a hose and spray nozzle attached. Abrasive media is loaded into the blast pot and sealed air-tight. Once sealed, the media is pressurized using compressed air. A valve at the end of the hose is controlled by the operator. When the valve is opened, compressed air forces the media to travel down the hose and spray out the nozzle.
Four factors affect the price of a blast pot: capacity, portability, construction quality and configuration.
Capacity: Typical blast pots hold 4 to 7 cubic feet of blast media per loading. As an example, the 650 XL model we offer with our Reliant Finishing Systems blast rooms has a 6.5 cubic foot capacity. As a general rule, the smaller the capacity the cheaper the unit, but reduced capacity will increase downtime for reloading.
Portability: The least expensive blast pot models come mounted to a skid or have attachment points so that they can be permanently mounted inside the blast room. Portable units, with wheels mounted to the base of the blast pot, are usually a bit more expensive.
Construction Quality: All blast pots offered by brand-name manufacturers are safe and well made. There are, however, small differences that can drive the price up, but may be well worth the expense. This is particularly true when dealing with premium hose fittings, roomy clean-out openings and more robust sealing systems. Even a simple feature like an adjustable stand versus a fixed one can improve convenience and increase throughput.
Configuration: Almost all common blast pots have one hose and nozzle for use by a single operator, but more expensive multiple operator configurations can be provided by some suppliers.
Other Factors To Consider When Purchasing A Blast Pot
Make sure the blast hose is of the same diameter and length. Find out if each blaster has a safety system to assure that the blasting operation stops instantly if the hose is dropped and the valve at the nozzle released. Determine the orifice size and construction material of each unit’s spray nozzles. Remember, the orifice is sized depending on the media you want to spray and the maximum output of your compressed air system. A larger nozzle takes more air and uses more media, but strips metal at a faster rate.
Part 3: Dust Abatement
When considering options for your blast room, it is very important to remember the difference between dust abatement and media reclamation.
Media reclamation refers to a system that allows you to collect and reuse the blast media (such as steel shot).
Dust abatement, on the other hand, refers to the fans and filters that remove the dust from inside the cabin while the blast room is being used. These fans and filters are separate from the reclaim system and are only used to reduce airborne particulate inside the blasting cabin.
Why is that important? A blast room produces a lot of dust. You are blasting old paint, rust and grime off your parts to get them ready to powder coat or paint. Without proper dust abatement, your operator will be working in a dust cloud that will render him unable to see what he is doing.
The media reclamation system does not move enough air to effectively remove airborne particulate from the enclosure. So, an operator using a typical reclaim unit won’t be able to see what he’s blasting unless the blast room also has a second system designed to filter the air inside the room.
Remember that dust abatement does not remove spent media or heavy debris from the blast room. Dust abatement systems (sometimes called dust collection, dust containment or dust control systems) ONLY affect the airborne dust inside the cabin.
Entry-level blast room models may not come with built-in dust abatement or they may feature a dust abatement system that uses disposable air filters. These simple systems draw fresh air into the room and route exhausted air through a series of filters to ensure that only clean air is returned to the facility. The filters are protected by steel baffles so they are not damaged during blasting, but they must be changed frequently during periods of heavy use. These filtration systems remove enough airborne particles to allow the operator to see what he is doing and to keep the air inside the booth relatively clean.
The most popular dust abatement systems use cartridge type filters. The filters are much longer lasting and can be set up to automatically self-clean using compressed air. These abatement systems usually have a large waste bin located under the filters, and the collected dust and debris falls from the filters into the bin during cleaning, so they may also be considered dust containment systems. The collected dust and debris is usually removed manually by the operator, but upgraded models exist which include a pump that transfers the dust and debris out of the collection area.
More expensive cyclonic dust removal systems are available, but for most buyers the cartridge filtration option offers the best mix of affordability and performance. Both cartridge and cyclonic systems provide excellent dust abatement and allow operators to see clearly inside the blast room, even though some amount of airborne particulate inevitably ends up settling on the floor of the enclosure.
Part 4: Choosing the Right Media Reclamation System
A powder coating shop can increase throughput, reduce blasting costs and assure code compliance by bringing their blasting operation indoors. They can further improve profitability by using recyclable abrasive media. To make the most of recyclable abrasives, an efficient recovery system is needed.
A media reclaim system usually has a low-volume/high-pressure intake that moves spent media, debris and dust out of the blast room. (As we said before, that does not make it a replacement for a good dust abatement system because the volume of air being exhausted is not enough to clear the air.)
It is not uncommon to see a blast room with dust abatement but no recovery system for spent blast media. Although recovery systems speed throughput even if the blasting media cannot be reused, most shops that use disposal blasting grit don’t use any type of recovery system.
Media Reclamation/Pneumatic Recovery Systems
Most sweep-in media recovery systems, which are often provided in addition to dust abatement equipment, offer an economical alternative to full-area media and waste recovery. A sweep-in system can be installed inside a new or existing blast enclosure. This will increase throughput and allow you to switch to recyclable abrasives. In a high-production environment, the cost savings and increased productivity can pay for the recovery system within months.
Conventional sweep-in media reclamation systems are pneumatic. These recovery systems efficiently remove most low to medium-density blast media, such as sand, glass beads, plastic, nut hulls and aluminum oxide. The recovered media, if reusable, can be recycled. A pick-up bin or trough can be mounted in a shallow pit in the floor for a true sweep-in operation, but is often surface mounted when the owner wants to be able to move the pick-up bin (or when the situation will not allow excavation of the shop floor). Some shops that use non-recyclable blast media still choose to install a pneumatic recovery system in order to increase throughput and prevent operators from spending time shoveling spent media into trash bins to be hauled away. They use the pneumatic system to transport the waste into large trash hoppers that can be emptied less frequently. With many pneumatic systems, debris is sorted from spent media via a classifier that relies on cyclonic airflow–debris is routed into trash hoppers and recovered media is returned to the blast pot’s feed system.
Media Reclamation/Auger (Screw-Type Conveyor) Recovery Systems
Auger systems are designed primarily for use with heavy, durable media like steel shot. These screw conveyor systems can be linked to a pneumatic recovery system when using lighter blasting media. For steel shot, a reclaim module mated to a bucket elevator can continuously process up to almost 200 cubic feet of media per hour. Augers are commonly available in lengths of 8’ to 20’, and can be provided in lengths of 50’ or more by special order. Most augers feature 6” helical flights. It is common for these systems to have integrated metering plates to prevent over-loading. Since they are used most often with steel grit and shot, most screw-type conveyors are mounted in an excavated pit so that the heavy-weight media can be pushed into them using a skid loader or easily shoveled in by hand.
Media Reclamation/Hopper & Bucket Elevator Recovery Systems
A hopper and bucket elevator recovery system serves as something of a hybrid between an auger type system and a pneumatic system. Since the pneumatic systems cannot transport heavy blast media, an elevator is required. The hopper and elevator system requires the operators to move the material into a recovery bin (just like pneumatic sweep-in systems). With diligent operator support, you can process up to about 180 cubic feet per hour of dense media, such as steel grit and shot. Typically, a small reclaim bin or hopper is mounted flush with the shop floor inside the blast enclosure and the operators use shovels or brooms to push spent media into it. When a flush-mounted hopper cannot be used, a smaller stand-alone or wall-mounted bin can be used and loaded by the operators using shovels.
Media Reclamation/Belt Conveyor Recovery Systems
Belt conveyor recovery systems are expensive, but use fairly simple technology to automate the recycling process. A typical complete belt conveyor system includes recovery bins, floor grating, a series of motor-driven belts, a bucket elevator, and an abrasive cleaner (such as an air wash system). When someone talks about a “full floor” or “full area” recovery system, they are usually talking about a belt conveyor system. There are also many versions that have collection built into only part of the blast room’s floor.
Belt conveyor systems include one or more collection bins installed in a recess in the blast room’s floor. Partial-area collection systems can be configured in a single linear run or in “H,” “L” or “U-shaped” patterns as required for the particular application. Reinforced floor grates, mounted flush with the blast room floor, cover the collection bins. Spent blast media falls through the grating and into the hoppers and travels through a metering tube before falling onto one or more conveyor belts below. A separate motor drives each belt, and conveys spent media and debris to a bucket elevator for transfer to the abrasive cleaner. As with auger or hopper systems, spent blast media is returned to a recovery bin. Specially designed buckets transport the abrasive blast media from the bin to a cleaner, where the abrasive material is separated from dust and debris. Debris falls into a waste container, dust is drawn into a separate dust collector, and reusable abrasive media falls into a hopper used to feed the blast pot.
Part 5: Safety Gear
Don’t skimp on safety. Professional quality safety gear can actually help operators be more productive, so it pays for itself fairly quickly. A good safety package starts at around $1,000. It usually includes protective wear, a helmet and respirator, and a good air filter system. Although it looks cumbersome, once an operator adapts to using this type of gear he is almost always working faster because he doesn’t have as many safety concerns and he can see what he is doing while working near the surface he is cleaning. This is especially true when dealing with detail work that requires a close-up view.
Not only can safety gear increase throughput, it helps reduce liability and prevent injuries to your employees. Safety gear is a win/win for your shop and employees and it’s an option we strongly recommend.
Part 6: Professional Installation
Some very expensive small and mid-size blast rooms arrive at your site ready to install. You connect the blasting and exhaust components, then add power and air. Because these pre-built rooms must ship via truck, these blast rooms’ interior dimensions are limited to heights and widths of less than 8’. Other than these models, there are a few DIY kits on the market, including affordable blast room kits manufactured by Reliant Finishing Systems.
For the vast majority of the blast rooms on the market, installation by factory-authorized technicians is required. In all cases it is recommended! The cost of installation labor is either built into the equipment price or listed as an add-on service. Whether you buy a small blasting room for occasional use or a giant blasting enclosure for non-stop blasting, professional installation helps assure that your equipment will operate safely and effectively.
Part 7: Material Handling
Once you start blasting, you’ll be faced with the need to safely support parts while a powerful stream of abrasive material is directed towards them. If your current racking and handling system has problems transporting parts from your powder coating booth to your oven, it probably won’t be secure enough to keep parts in place while they are being blasted.
You can develop a better way to secure parts through the entire prep and coating process, but many coaters go to a manual or semi-automatic system where parts are dealt with during blasting (and chemical pretreatment if used) and then transferred to a different hanging system for coating and curing.
No matter what type of blast or pretreatment system you are considering, the experts at Reliant Finishing Systems can answer your questions and provide the equipment you need to get the perfect finish every time. Give us a call today.